ACA Fall Newsletter

Articles by e-mail or on diskettes are especially welcome. Deadlines for newsletter contributions are: February 1, May 1, August 1 and November 1st. Matters pertaining to advertisements, membership inquiries, or use of the ACA mailing list should be addressed to:

Marcia J. Colquhoun, Administrative Manager
American Crystallographic Association
c/o Hauptman-Woodward Medical Research Institute
73 High Street, Buffalo, NY 14203-0906
phone: 716-856-9600, ext. 321; FAX: 716-852-4846
E-mail marcia@hwi.buffalo.edu
ACA HOME PAGE http://www.hwi.buffalo.edu/ACA/

ACA Newsletter (ISSN 1058-9945) Number 3, 1997. Published four times per year in the spring, summer, fall and winter for the membership of the American Crystallographic Association, P.O. Box 96, Ellicott Station, Buffalo, NY 14205-0096. Membership in the ACA includes a non-deductible charge of $1.75 from membership dues to be applied to a subscription to the ACA Newsletter. Second-class postage paid at Buffalo, New York. POSTMASTER: Send address changes to ACA, c/o 73 High St., Buffalo, NY, 14203.

President's Column

There's a blissful period between talking with a reporter and seeing the published article, and the deadline for this column came during just such a time. A reporter from Chemical & Engineering News, who was preparing an anniversary edition article, wanted my comments on a story he had written on crystallography. Part of my satisfaction came from the tacit recognition by the American Chemical Society, the publishers of C&E News, that crystallography had made so many important contributions to chemistry. And, of course, it's always a pleasure to recall some of the highlights of our science and the people who contributed to them. But the greatest enjoyment came from outlining why crystallography was likely to be even more important in the future. Improved instruments such as diffractometers with CCD detectors will bring about an even steeper increase in the yearly growth of new crystallographic analyses; powerful synchrotron sources will change our ideas about time scales, resolution, and sample size; and developments in databases and informatics will allow us to keep track and make sense of all the results pouring in. When the call ended, things seemed just fine with crystallography. Of course there are a few obstacles that we'll have to overcome for such a rosy future, but none are insurmountable. Education and money are the issues at the top of my list.

Ironically, while structural results are proliferating, crystallographic education is shrinking. Each year there are more people doing crystallography and fewer being formally instructed in how to do it. In departments where there used to be crystallography courses, there are now CCD diffractometers pouring out structures. It is impossible to completely counter such trends, but the ACA has begun to work on dealing with some of the more pernicious aspects. We've begun educating journal publishers on the necessity of recognizing the contributions crystallographers make to publications as well as the necessity of requiring that sufficient documentation be made available to the scientific community so that structural results can be independently analyzed. We still have a long way to go on both recognition and data deposition, but we've made a reasonable beginning. We've also continued to support the ACA Summer School, which is doing a great job in its new home at the University of Georgia, and the ACA executive council is eager to entertain proposals for other training courses.

All the possibilities for new crystallographic laboratory equipment, national resources, and databases inevitably lead to the question of how we as a community will pay for them. The search for funding is a hardy perennial of a scientific career, and I first became aware of the f-word as a graduate student thirty years ago. Even though funding is a constant problem, there have been changes, and in an era where funding for many worthy ventures other than scientific research is being reduced or radically restructured, an attitude of entitlement is not possible. Part of our answer will have to be developing a variety of ways to explain what we're doing and why we're doing it-education in the broadest sense. As an initially reluctant participant in these efforts, I'd like to put in a plug for the tonic effects they can have on your own outlook. It's easy to tell a colleague about your work; it's tough to tell a gaggle of bemused onlookers at a Farmers Market booth about what you do. But there's nothing like the satisfaction of hearing someone say, "That sounded pretty cool."

Jon Clardy

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Membership Column

Welcome to our new Membership News column. Through this column we hope to keep you up-to-date with membership information. We encourage you to contact us with any questions or concerns regarding your membership or with ideas of what you would like to see included here.

At long last, Transactions Volume 30, "Likelihood, Bayesian, Inference and Their Application to the Solution of New Structures" is complete and being printed. Members with standing orders should receive their copy in November. Volume 31, "Structural Tools in Organometallic and Coordination Chemistry" is scheduled for publication in November, with distribution early in 1998. Copies of Volumes 30 and 31 are available to ACA members for $10 through the membership department.

Ballots for election of 1998 Council Officers, Standing Committee Members and Special Interest Group Officers were mailed October 20 to members who have paid their 1997 membership dues. If you do not receive a ballot but think your dues are paid, please contact us so we may correct our records. Ballots must be returned by November 21. Please vote. It matters.

The end of the year is approaching which means invoices for 1998 membership dues will be sent out soon. Included with your dues invoice will be an 'update your address' form for members to fill out and return with their dues payment. This form is very important because it will contain a place where members will be asked for permission to place their address information on the ACA web site in a searchable electronic database. We hope to have the database up and running early in 1998. Please take the time to fill out this form out so we can update our records with your correct address, phone, fax and e-mail addresses.

For further information or if you know anyone interested in becoming a member, please contact us at

ACA
PO Box 96, Ellicott Station
Buffalo, NY 14205-0096
tel. (716)856-9600 ext. 379
fax. (716)852-4846
aca@hwi.buffalo.edu
www.hwi.buffalo.edu/ACA/

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ACA Council Meeting, St. Louis

There are a total of 2422 active members of the ACA in 1997 compared to 2287 in 1996. The ACA directory has been sent to members; the final cost was $13,800. In the next request for dues, members will be asked if their address information can be accessed from the ACA world wide web page. The information will be listed in two ways, by name and by location, as in the printed copy.

The ACA world wide web page (www.hwi.buffalo.edu/ACA/) has been reorganized by the ACA office. Comments are welcome to marcia@hwi.buffalo.edu. The "Careers in Crystallography" brochure has been added to the web page under the heading Careers & Education. Virginia Pett would like to add links to other sites featuring crystallography education. You can send suggestions to her at pett@acs.wooster.edu.

Marcia Colquhoun proposed a set pattern for meetings: workshops all day Saturday, meeting begins Sunday morning, banquet Wednesday night, meeting ends Thursday afternoon, no excursion. This pattern enables attendees to stay over Saturday night, decreasing airline fares. Plans are well underway for the Washington, DC, meeting in 1998 (Program Chair, Louis Delbaere, Local Chairs, Terrell Vanderah and Vicky Lynn Karen), the Buffalo meeting in 1999 (Program chair, Steve Ealick, Local Chair David Smith) and the Minneapolis meeting in 2000 (Local Chair Bill Gleason).

Two committees were appointed. The nominating committee for the 1998 ACA election will be chaired by Ed Arnold, and include Carol Huber and Helen Berman. The Fankuchen Memorial Award committee will be chaired by Carol Brock and include Marvin Hackert, Jim Jorgensen and Ron Stenkamp.

Virginia B. Pett

Address Change - Virginia Pett - ACA Secretary

Virginia B. Pett
Professor of Chemistry
The College of Wooster
Chemistry Department
943 College Avenue
Wooster, OH 44691-2363
tel. 330-263-2114
fax. 330-263-2386
e-mail pett@acs.wooster.edu

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Fankuchen Award Nominations Requested

The triennial presentation of the Fankuchen Memorial Award will be made at the July 1998 meeting of the American Crystallographic Association. The Award was established in 1971 in memory of Dr. I. Fankuchen, Professor at the Polytechnic Institute of Brooklyn from 1942 to 1964. The award recognizes contributions to crystallographic research by one who is known to be an effective teacher of crystallography. There are no geographic or age restrictions. Previous awardees include J. Glusker & K. N. Trueblood; L. D. Casper; D. Sayre; M. S. Rossmann; L. H. Jensen; D. Harker; D. Hodgkin; A. Guinier; and M. J. Buerger. The honoree delivers lectures at the Polytechnic Institute of New York, at several additional colleges, and to the ACA. The award carries a honorarium of $2000; an additional $2000 is available for travel expenses incurred in connection with the lectures. Nominations are invited from all branches of the crystallographic community. Letters of nomination and supporting documentation should be sent to one of the members of the Award Committee (see below). Accomplishments of the nominee that would make the Fankuchen Award especially appropriate should be identified. The closing date for receipt of nominations is 19 December 1997.

Carolyn Brock (Chair)
Department of Chemistry
University of Kentucky
Lexington, KY 40506-0055
cpbrock@ukcc.uky.edu

Marv Hackert
Department of Chemistry & Biochemistry
University of Texas at Austin
Austin, TX 78712
m.hackert@mail.utexas.edu

Jim Jorgensen
Materials Science Division
Building 223
Argonne National Laboratory
Argonne, IL 60439
jim_jorgensen@qmgate.anl.gov

Ron Stenkamp
Dept. of Biological Structure
Box 357420
University of Washington
Seattle, WA 98195-7420
stenkamp@u.washington.edu

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Sir John Kendrew - 1917 - 1997

Nobel laureate John Kendrew died August 23 in Cambridge. Born in Oxford, Kendrew shared the Nobel Prize for Chemistry in 1962 with Max Perutz for their crystallographic studies of myoglobin and hemoglobin. Both were members of the Medical Research Unit for Molecular Biology at Cambridge University at the time. Kendrew served as a scientific advisor to the Air Ministry during World War II and chaired the Defense Scientific Advisory Council in the 1970s. He was later knighted for his services. In addition to serving in academic posts at both Oxford and Cambridge, he was the first director-general of the European Laboratory of Molecular Biology in Heidelberg, Germany. A more complete description of Kendrew's career will be presented in the IUCr Newsletter.

CISTI's Catalogue Now on the World Wide Web

The Canada Institute for Scientific and Technical Information (CISTI) has released its library catalogue on the World Wide Web. The catalogue contains over 50,000 serial titles, half a million books and conference proceedings and technical reports. CISTI has one of the largest collections of published information in science, engineering and medicine in the world. The new web-based catalogue also contains records from the Canadian Agriculture Library.

The catalogue offers a wide range of flexible search options, including the ability to search by call number, to simulate browsing the shelves. By clicking on the author's name of a bibliographic record, other titles by that author are retrieved.

One of the most powerful features of the new system is the option to order any item - a copy of an article, book or report - from anywhere in the catalogue. The orders are sent automatically to CISTI's Document Delivery Service. Over half a million document orders are processed each year.

The catalogue can be searched 24 hours a day, seven days a week, with client service from Monday to Friday, 9:30 am to 4:30 pm EST. For those without web access, the catalogue is also available by Telnet at cat.cisti.nrc.ca.

Unlimited catalogue searching is free. Free registration is required before placing an order for a document, and document charges apply. The documents can be delivered in print, on-line or by fax, and most orders are processed within two days.

The catalogue is available at http://cat.cisti.nrc.ca.

For more information, contact:
Elizabeth Katz, CISTI
Telephone: 1-800-668-1222 or (613)-993-3854
e-mail: elizabeth.katz@nrc.ca
CISTI's web site is http:/www.nrc.ca/cisti

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Canadian Division Election for Secretary - Candidates Statements

Barry Phipps

Associate Professor, Dept. of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4.

Education: B.Sc. in Cell Biology, University of Victoria (1979); Ph.D. in Biochemistry, University of Victoria (1988); MRC Postdoctoral Fellow, Max-Planck Institute for Biochemistry (1988-91); Research Associate, NRC Institute for Biological Sciences (1991-95).

Professional Activities: Member of ACA, Protein Society, and Canadian Institute for Synchrotron Radiation.

Research Interests: X-ray and electron crystallography of proteins, molecular chaperones, bacterial S-layer proteins, protein folding.

Statement: The ACA provides an excellent vehicle to promote the interactions and interests of Canadian crystallographers and their fellowship with the international crystallographic community. I have benefited a great deal from the personal contacts and exchange of information afforded by the Annual Meetings and newsletters. It would be my privilege, if elected, to contribute to the excellent efforts of the Canadian Division in supporting crystallography in Canada. I am a strong believer in the value of working together toward mutually agreed-on goals. The Canadian Division has been and will continue to be effective in providing us with this opportunity.

Jim Britten

Manager, X-ray Facility, Department of Chemistry, McMaster University, Hamilton, Ontario, CANADA, L8S 4M1.

Education: Hon. B.Sc. in Chemistry, 1977, St.F.X.U.; Ph.D. in Chemistry, 1984, McMaster.

Professional Activities: Member ACA, Chair of Service SIG, 1994.

Research Interests: Inorganic, organometallic, and organic single crystal structure determinations for the problem cases: twinned samples, very small crystals, poor diffractors, etc., i.e. pushing the envelope (not necessarily in the secretarial sense).

Statement: As the software, hardware, and techniques of the science and service of crystallography have progressed, diffraction analyses have become a more important part of scientific research in Canada. The Canadian Division of the ACA has a responsibility to help guide in the development, direction, education, promotion, and availability of crystallography, crystallographers, and instrumentation across the country. It must also take a role in opening the lines of communication between crystallographers. It would be a privilege to assist our group in fulfilling its mandate.

Contributors to this Issue

Cele Abad-Zapatero, Wade Adams, Craig Behnke, Helen Berman, Tom Brett, Jim Britten, Carolyn Brock, Jon Clardy, Marcia Colquhoun, George De Titta, Ashley Deacon, Louis Delbaere, Takeshi Egami, Larry Falvello, Judy Flippen-Anderson, Gary Gilliland, Bianca Hovey, Evelyn Jabri, Holly Jing, Jim Kaduk, Marge Kastner, Herbert Klei, Joseph Krahn, Craig Kundrot, Martha Ludwig, Joseph Luft, Gary Newton, Joel Oliver, Barry Phipps, Charles Prewitt, David Long Price, Fred Ross, Frank Rotella, Dale Sayers, Piotr Sliz, Eddie Snell, Geeta Sood, Ron Stenkamp, Barry Stoddard, David Templeton, Tom Terwilliger, Winnie Wong-Ng, Josef Zwanziger. Photos: Jim Britten, Bill Duax, Evelyn Jabri, Gary Newton, Barry Phipps, Charles Prewitt.

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Arthur Bienenstock to be Nominated as Associate Director for Office of Science and Technology Policy

President Clinton today announced his intent to nominate Dr. Arthur Bienenstock as the Associate Director for Science at the Office of Science and Technology Policy, Executive Office of the President.

Dr. Bienenstock, of Stanford, California, is the Director of the Stanford Synchrotron Radiation Laboratory, Stanford University, where he also serves as Professor in the Departments of Materials Science and Applied Physics. Additionally, he has served as Vice Provost for Faculty Affairs at Stanford and was Stanford's first faculty affirmative action officer. Over the years he has been a member of many distinguished advisory committees, has organized major national and international conferences, and has been awarded distinguished research fellowships. Currently, Dr. Bienenstock is serving as a Member on the National Research Council on Condensed Matter and Materials Physics of the National Academy of Sciences. For a number of years, he was the Vice Chairman of the Board of Trustees for the Cystic Fibrosis Foundation. Dr. Bienenstock received a B.S. and an M.S. in Physics from Polytechnic University of New York and a Ph.D. from Harvard University in Applied Physics.

The Office of Science and Technology Policy (OSTP) was established in 1976 under the National Science and Technology Policy, Organization and Priorities Act. The Associate Director for Science is one of the Administration's key positions in the area of science along with the Director of the National Institutes of Health and the Director of the National Science Foundation. The Science Division strives to maintain the United States' global leadership in science, mathematics, and engineering. This Division also participates in setting Federal policies related to some of the most important health, agriculture, energy, education, and national security issues.

THE WHITE HOUSE, Office of the Press Secretary

We gratefully acknowledge the continued support from our

ACA CORPORATE MEMBERS

Area Detector Systems Corp., Poway, California

B.A. Frenz & Associates, Inc., College Station, Texas

Bibliothek Technische Hochschule, Hanover, Germany

Blake Industries, Inc., Scotch Plains, New Jersey

Brookhaven National Laboratory, Upton, New York

Charles Supper Company, Inc., Natick, Massachusetts

Crystal Logic Inc., Los Angeles, California

Cyberlab, Brookfield, Connecticut

Digital Equipment Corporation, Maynard, Massachusetts

Diversified Scientific, Inc., Birmingham, Alabama

Enraf-Nonius, Co., Bohemia, New York

Fuji Medical Systems, USA, Inc., Stamford, Connecticut

Hampton Research, Laguna Hills, California

J. Schneider Electrotechnik GmbH, Offenburg Germany

Luxel Corporation, Friday Harbor, Washington

Molecular Structure Corp., The Woodlands, Texas

Osmic, Inc., Troy, Michigan

PerSeptive Biosystems, Inc., Framingham, Massachusetts

Protein Solutions, Inc., Charlottesville, Virginia

Scientific Information Service Inc., Larchmont, New York

Siemens Energy & Automation, Madison, Wisconsin

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The Lunar Element and Our Collective MADness

In the old part of Grenoble (Department of Isère and capital of Dauphiné province) in France, there is a café named "Café de la Table Ronde", right across from the old Palais de Justice in the Place de St. André. According to some of the newspaper clippings hanging from its rustic walls, this coffee house was the second in France, founded in 1739, seventy years after the first coffee house in France, the "Café d'Europe" in Paris. Among its clientele this café boasted actors such as Fernandel and Gerard Depardieu; folksingers and balladeers like Jacques Brel and George Brassens, and writers of the caliber of Pierre Choderlos de Laclos (1741-1803; Les Liaisons Dangereuses, object of an American film by the same title) and Stendhal (1783-1842; pseudonym of Marie-Henri Beyle, Le Rouge et le Noir), who was a native of Grenoble. I am certain that in most recent years it has also been the place of gathering for many of the most illustrious scientists that visit the ESRF in Grenoble every year. However, they are not listed yet.

I was sitting at this café late in the evening on June 16, 1996 at the conclusion of the workshop on Multiple Anomalous Diffraction (MAD, Grenoble, June 10-16, 1996) making time until the departure of my TGV train back to Paris. The square where the outdoor tables were set was full of life, and a full moon was shining up on one of the corners of the quadrilateral defined by the roofs of the buildings around me, including the parish of Saint André. As I remember that night, and the subsequent developments in our laboratory, I feel as if, in that particular moment, I was "moonstruck" in a scientific rather than romantic manner. At that time, our laboratory had just solved, in a matter of only a few weeks, its first structure using the MAD methodology. From then on, I have felt captivated by the "power and sheer elegance of the method(1)" derived from the substitution of sulfur by selenium in the protein.

Selenium (from Greek selene, "moon") derives its name from its silvery appearance and was recognized as an element in 1818 by Jõn Jacob Berzelius. Its location in The Periodic Kingdom (2) is in the Eastern Rectangle (the p-block), right after the isthmus that connects the strong metals (Western rectangle) with the nonmetallic elements and has the yellow sulfur as its northern neighbor. Its gray metallic, lunar-like, appearance was probably the main reason behind its name but its ability to exist in several different colored forms, akin to the phases of the Moon, established for me another connection with our night planet. As an amorphous (noncrystalline) powder, it is red but transforms easily into a black vitreous glass. As a crystal, it can be red or gray with the latter being the most stable under ordinary conditions. By itself it is not poisonous but many of its compounds are very toxic. However, it is also an essential mineral that has to be provided in the diet of certain animals.

After that night, it seems as if I am under the spell of this gray metalloid element and I think that I am not alone in view of the many structures that are solved nowadays using this methodology. The spell of this lunar element on protein crystallographers is undoubtedly due to the unique properties of its electron cloud with an absorption K-edge at 12.658 KeV (0.9795 Å). Its strong attractive influence is also due to the fact that it can be easily incorporated into our protein samples and that, most of the time, our crystals do not even notice it (3,4).

As judged by the number of protein structures solved by this method in the last year (5), my lunar hallucinations have spread to a large number of members of the protein crystallography community and may soon reach the level of a collective MADness. The origins of this hysteria can be traced back for a number of years and I will not elaborate on this (6,7). However, I would argue that there must be an instigator, a culprit, for such a large group of "intelligent" people to become engulfed in such a collective state of agitation. I have not taken a poll but I think that, for once, the community is unanimous and unambiguous as to who that person is, and I will not even have to name the author of such witchcraft.
May these few lines be an expression of respect and admiration for the leader of this unusual and benign cult. May these words pay homage to one of the unsung heroes of the structural revolution in Biology (who was recently justly honored with the Gregori Aminoff Prize in Sweden)*. May these letters express my personal gratitude, that of my colleagues, and the one from the community at large, to such an "anomalous" and visionary colleague. He has opened for us a path to solve new structures, illuminated by the pale light and color of the lunar element combined with the brightness and tunability of our most brilliant X-ray sources. When I go to the Café de la Table Ronde next time, I would like to see the names of some scientists among its illustrious clientele, and our MADman among them.

1. Words used by Dr. Steve Cusack at the opening of the Workshop at the EMBL Grenoble Outstation.

2. The Periodic Kingdom: A Journey into the Land of the Chemical Elements. by P.W. Atkins. BasicBooks. A Division of Harper Collins Publishers, 1995.

3. Cowie, D.B. and Cohen, G.N. (1957). Biochim. Biophys. Acta., 26, 252-261.

4. Hendrickson, W.H., Horton, J.R. and LeMaster, D.M. (1990). EMBO J., 9, 1665-1672.

5. Abstracts of the Annual ACA meeting in St. Louis, Missouri, July 19-25, 1997.

6. Hendrickson, W. (1985). Transactions of the American Crystallographic Association, 21, 11-21.

7. Macromolecular Crystallography with Synchrotron Radiation, by J.R. Helliwell, Cambridge University Press, Cambridge, England, 1992.

* See the IUCr Newsletter, 1997, volume 5, issue 2, page 19, for the news item describing the awarding of the Aminoff Prize.

Cele Abad-Zapatero

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ACA97 - St. Louis - July 19-25, 1997

The ACA held its 1997 annual meeting at Union Station in St. Louis this summer. Lee Brammer (Local Chair) and Bill Stallings (Program Chair) organized a very busy, effective, and well-attended meeting.

Many awards and honors were presented at the meeting. Carroll Johnson was presented with the ACA's Buerger Award, Chris Nordman received the association's Patterson Award, and David Long Price was the recipient of the group's Warren Award. These awards were given in appreciation of the major contributions these scientists have made to crystallography and molecular structure research.

Pauling Prize Winners 1997

Pauling Prizes are awarded for student posters. The awardees this year are:
Tom J. Brett - Poster P263 - Interpreting disorder in b-Cyclodextrin Inclusion Complexes: Methods, Results, and Their Implications (T.J. Brett, J.L. Clark, R.K. Shoemaker, C.R. Ross II and J.J. Stezowski)
Joseph M. Krahn - Poster P07 - Structure of the Active Allosteric State of the Substrate Analog complexed E. coli Glutamine PRPP Amidotransferase (J.M. Krahn and J.L. Smith)
Piotr Sliz - Poster P101 - Structure of Enzyme IIAlac from Lactococcus lactis - A Trimer of Three-Helical Bundles (P. Sliz, R. Engelmann, W. Henstenberg, E.F. Pai)
Honorable Mentions:
Craig A. Behnke - Poster P182 - Cutting up the Clotting Cascade: The Structure of CHFI, an Inhibitor of a Single Coagulation Enzyme (C.A. Behnke, V.C. Yee, L.C. Pederson, I. Le Trong, S.S. Kim, G.R. Reeck, R.E. Stenkamp and D.C. Teller)

Dmitry V. Fomitchev - Poster P268 - The First Side-bound NiNO Complex: X-ray Diffraction Study of the Ground and Excited States of [NiCp*(NO)] (D.V. Fomitchev and P. Coppens)
Bianca Hovey - Poster P44 - A Potential Anti-Assembly Agent for AB5 Toxins (B. Hovey, E. Merritt, C. Verlinde and W. Hol)
Holly Jing - Poster P76 - Crystal Struct ure of Complement Factor D Complexed with Isatoic Anhydride at 1.5 Å Resolution (H. Jin, D. Moore, Y.S. Babu, J.E. Volanakis and S.V.L. Narayana)
Geeta Sood - Poster P242 - Alkylation of Purine Bases: Why, How and Where? (G. Sood, C.H. Schwalbe and W. Fraser)
Award Committee: Patrick Loll (chair), Jeff Dechamps, Sylvie Doublie, Qi Gao, Despina Louca, Martin Horvath.

Oxford Prize

Joel M. Harp from the University of Tennessee-Oak Ridge Graduate School of Biomedical Sciences, and Life Science Division, was awarded the Oxford Prize at the American Crystallographic Association annual meeting 19-25 July 1997 in St. Louis, Missouri.

The Oxford prize, sponsored by Oxford Cryosystems, is awarded to the presenting author of the poster at the ACA annual meeting that best depicts cryocrystallography (such as the development of new techniques, unique applications, or the analysis of systems using cryogenic conditions). The award winning poster is titled: "Protein Crystal Annealing: Overcoming Increased Mosaicity Associated with Cryocrystallography" Joel M. Harp, D.E. Timm and Gerard Bunick from the University of Tennessee-Oak Ridge Graduate School of Biomedical Sciences, and Life Science Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.

Award Committee: Stephen Ginell (chair), Tom Terwilliger, Ravi G. Kurumbail, Sean Parkin.

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Young Scientists Activities at ACA97 a Success

The Young Scientist's Special Interest Group (YSSIG) held three activities at ACA 97: a mentor:mentee dinner, a midweek mixer, and an evening session. Approximately 100 young scientists and mentors gathered in the Grand Hall of the Hyatt Hotel to begin an evening of fine dining. With help from Matt Redinbo, perched above the crowd in the window sill, mentees selected a mentor. After a short trip on the metro, the crowd arrived at the University Hill area of St. Louis where they descended on the local restaurants. Thanks to Matt Redinbo and Pete Trickey for organizing the mentor:mentee dinner.

Later in the week, both young and experienced scientists took over the second floor of the St. Louis Brewery. Their exquisite loft made an ideal setting for relaxed conversation. Thanks to the Charles Supper Company and the ACA for funding the mixer and thereby providing an opportunity for 250 crystallographers to enjoy a large selection the local microbrews.

On Wednesday evening, the ACA's attention focused on the YSSIG session. This year, the session addressed the issue of Future Trends and Hot Topics in X-ray Crystallography. Further details about that session can be found in the following reports.

For a more detailed review of the YSSIG session as well as a listing of upcoming activities and career information, visit our page at http://resolution.colorado.edu/~jabri/yssig.html. Get involved with the YSSIG. It's a great way to meet fellow crystallographers.

Evelyn Jabri

Future Trends and Hot Topics in X-Ray Crystallography

Distinguished panel members Dick Harlow (Dupont), Janet Smith (Purdue University), Wim Hol (U. Washington), Judy Flippen-Anderson (Naval Research Lab), and Cele Abad-Zapatero (Abbott Labs) discussed how the science of crystallography is changing. Panelists agreed that the profile of a crystallographer has changed in the last decade. We have progressed from getting crystals and solving a structure to doing that and using other biochemical and biophysical techniques to approach the whole problem from different perspectives. This trend will continue in the next 10-20 years. Janet Smith suggested that the young scientists obtain a broad training with crystallography as the focal point. Changes in image will affect how we do science, specifically, which scientific questions crystallographers approach. Panelists urged the audience to think about the structure as the beginning and not the end of a project, and to consider working on larger, more complex systems. Crystallographers should examine how structures of small molecules or large biological complexes change with time, temperature, stress, and environment. How can we carry through these research projects? "Get thee to thy synchrotron" was Dick Harlow's suggestion. Wim Hol pointed out that other fields will also significantly affect how we do crystallography. The genome project and molecular biology will increase the number of proteins we will study. Material science and miniaturization could provide an "MCC, a magic crystallization carpet," on which we will grow bigger diffraction quality crystals. Advances in physics, theoretical and computational science will increase the speed with which we obtain data and the final structure.

Trends in the job market and funding are a little more difficult to predict. Cele-Abad-Zapatero notes that the new beamlines will certainly require additional research staff. In addition, Wim Hol expects that new types of jobs will develop as the field of crystallography matures. The funding prospects will depend on the party in power and their attitude towards science. Judy Flippen-Anderson recommended that we communicate with Congress and let them know what we do, why it's important, and why we should be funded.

Evelyn Jabri

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General Interest Group Sessions

Four half-day oral sessions and a poster session organized by the GIG included a wide variety of papers on subjects not included in the more narrowly focused sessions of the Special Interest Groups. This Group gives a forum for work which is novel or off the beaten path or for some other reason does not fit elsewhere in the program. It seeks to broaden the coverage of the program and to open it up to those who might otherwise be excluded.

General Interest Group - Quasicrystals, Incommensurate and Surface Structures

A session on Sunday, "Quasicrystals, Incommensurate and Surface Structures," was devoted to materials which in one way or another lack three-dimensional periodicity. Arcs of diffuse scattering, observed in the diffraction patterns of certain quasicrystals, were explained by P. C. Gibbons with a model based on short-range correlations between icosahedral clusters. The model predicts similar diffraction arcs for glasses and polycrystalline samples when similar short-range order is present. It reminds us that the distinction between these states of matter is not sharp when there is disorder. The azimuthal asymmetry of three-beam diffraction gives the phases of triplet invariants; R. Colella described such experiments with Al-Pd-Mn quasicrystals and circularly polarized X-rays which show that this material is not centrosymmetric. D. L. Dorset introduced us to the very complex crystallography of mixtures of n-paraffins and the slow transitions which occur from one state of order/disorder to another. H. Baltes reported how phase information was gained for diffraction by a synthetic aperiodic multilayer when the scattered beam interfered with that scattered by a thin gold overlayer. This method may be useful for studying buried interfaces or two-dimensional macromolecular crystals. Direct methods were used with both X-ray and electron diffraction data to solve several surface structures as described in three papers presented by L. D. Marks, E. Landree and C. Collazo-Davila.

General Interest Group - Theory

Thursday morning a "Theory" session was led off by Herb Hauptman who described how relationships between the sines of the triplets for a fixed choice of enantiomorph can be utilized in the direct method of structure solution. Julie Cross then discussed the consequences of disorder (as described by a Debye-Waller factor) for DAFS (Diffraction Anomalous Fine Structure) measurements. David Brown presented a simple model for the thermal expansion of bonds based on a consideration of bond valence. He pointed out that an extension of this approach could give a model for cell expansion but would be difficult because the temperature dependence of the angles is much more complicated than the temperature dependence of the distances. Yvon LePage described a new program that generates the general positions and Wyckoff positions for all the space groups (standard and non-standard settings) listed in International Tables. Go Ueno described a GUI (Graphical User Interface) that allows integration of SHELXL-93 into the TeXan set of programs. Cam Hubbard reported on thermal stresses derived from crystallographic measurements of directionally solidified eutectics formed from NiO and cubic zirconia. The 0.1 mm grains are formed from alternating lamellae 0.2-1.0 micrometers thick that are crystallographically aligned. Strong bonding along the NiO-ZrO2 interfaces is indicated both by the large residual stresses and the tendency of cracks to run across, rather than along, the interfaces. Dave Templeton finished the session by discussing the supposed discovery of the element masurium, atomic number 43, which was reported in 1925 together with the (uncontested) discovery of rhenium. Weak lines in ill-described X-ray spectra of extracts of Nb and Pt ores were the basis for the claim. Dave presented several explanations, the most satisfactory of which involved a calibration error.

General Interest Group - Experiment

In the afternoon session ("Experiment"), C. Yip and M. DeFelippis described the exploitation of tapping mode atomic force microscopy to investigate the crystal growth mechanism of insulin analogs. E. Valente discussed the resolution of racemic mixtures emphasizing solvent effects. The use of neutron diffraction to determine the absolute stereochemistry of a deuterium-labeled species was presented by T. Koetzle. The determination of the structure of minerals from very small needles was presented by J. Pluth. K. McConnell and R. See discussed bond distance trends based on analysis of data from the Cambridge Structure Database.

General Interest Group - Techniques and Apparatus

Friday morning ("Techniques and Apparatus"), Bill Clegg described the design characteristics and modes of operation of a newly commissioned synchrotron beamline at Daresbury, UK, and listed some of its early scientific results. Alan Pinkerton showed how one can correct for l/2 contamination in area-detector diffraction patterns by recording the intensities of half-integer peaks, at no cost of additional exposure time. He described his experience with nine small-molecule crystals and a CCD detector. Anthony Martin told how a simple open flow helium ESR cryostat was adapted for use with a small-molecule CCD diffractometer at modest expense. The speed of the CCD diffractometer brings the cost of helium within reason. Experience with perturbation crystallography (change of structure in response to an applied field) at ESRF was reported by G. Heunen. A key innovation is a broad energy band pass monochromator which permits an integrated intensity to be measured without movement of the crystal. Mark Pressprich described the properties and advantages of Goebel mirrors as monochromators and focusing elements. These mirrors are synthetic multilayers with nonuniform spacing. The characteristics of and experience with Siemens SMART CCD detectors were the subject of three papers by Roger Durst, James Phillips and Jim Fait.

D. Templeton, C. Brock, M. Kastner and F. Rotella

Contemporary Small Molecule Crystallography: Problems, Programs and Pitfalls

The one-day session "Contemporary Small Molecule Crystallography: Problems, Programs and Pitfalls" was attended by a large and sometimes animated audience that participated freely in the four open discussion sessions that punctuated the technical talks.

The session was opened by Phil Fanwick, whose talk was entitled, "The Problem is Not with Our Structures but with Ourselves: Why We Mess up Crystal Structures." The talk dealt with misunderstandings between chemists and crystallographers regarding the capabilities and limitations of diffraction techniques, with problem structures as examples. The presentation ended with a call for more and more meaningful crystallographic education at the university level.

The talk called "Direct Methods for Large Small Structures," by George Sheldrick, treated the standing room only audience to a description of the direct-methods solution of several "small large structures," the largest of which had 2040 protein atoms and another 60% solvent. Eight iron atoms were present; otherwise, there was nothing in the data that facilitated the solution of the structure. The speaker gave detailed descriptions of his method program "Half Baked" and also of the "Shake and Bake" methodology of Weeks, Miller, DeTitta and Hauptman. The breaking of the 1000- and 2000-atom barriers was described factually, but the importance of what was being presented was not lost on the audience; and much informal discussion took place later regarding this talk.

A presentation by Patrick Loll, "Vancomycin-Ligand Complexes," further developed the direct-solution theme with the description of Shake-and-Bake solutions of structures with up to 404 atoms. The necessity of having high-resolution data, taken at a synchrotron source, was emphasized.

Two talks on methodology "Missed Symmetry and How to Avoid Being Marshed" by Anthony Spek, and "Absorption Corrections in the Context of Problem Structures," by Larry Falvello, focused on two currently much-discussed aspects of structure determination. The presentation on missed symmetry described some of the speaker's own experiences and also software for identifying missed symmetry. In the presentation on absorption, examples were given of cases in which both measured and a posteriori calculated absorption corrections lead to incorrect results. The term "absorption corruption" was later offered by William Clegg for describing attempted absorption corrections that go wrong and lead to errors in the data.

Robert Scheidt gave a presentation on "An Interesting Choice of Space Group," using the redetermination of the structures of nickel etioporphyrins to illustrate the effects of pseudosymmetry in causing the appearance of disorder in cases for which the situation is not really clear. Ewa Skrzypczak-Jankun, in her presentation "Just How Important Can One Hydrogen Be?" took a close look at the effects of scientific prejudice illustrated by dogma regarding N-H distances on the possible interpretations of structural results.

The afternoon sessions opened with two presentations on the state-of-the-art topic of twinning. Regine Herbst-Irmer dealt with single-reciprocal-lattice twins and gave several examples of the difference that a correct treatment makes. Robert Sparks spoke on his programs for deconvoluting diffraction patterns from multi-component samples usually referred to as twins but conceptually different from the merohedral and fully superimposed cases.

The session also included a presentation by Chuck Campana of Siemens regarding the virtues of the SMART CCD-based detector system in non-routine crystallographic applications.

The final part of the day of lectures consisted of three well-received presentations regarding publication. George Ferguson, co-editor of Acta Crystallographica, Section C, demonstrated how an editor can be constrained, before moving on to a description of new Acta validation tests that are intended to assist in achieving automated assessment of structure determinations. The following talk by Judy Flippen-Anderson, titled, "Let's Make a Note of That," dealt with the daily activities of those who determine structures and those who publish them. The speaker presented a long list of useful tips for avoiding both inconvenience and errors. The final talk of the day was given by Guy Orpen, Scientific Editor of Dalton Transactions, who described the priorities of the editors, reviewers, and authors, and emphasized the roles of the latter two groups in establishing the criteria for publication.

A long, lively discussion followed the final section of the program. George Ferguson indicated that the Acta criteria were not carved in granite, and that publications could always be treated on a case-by-case basis if there were deviations from what the automated procedures considered to be acceptable quality. Guy Orpen reiterated the integration of structural results in the evaluation process at Dalton, where the key question is whether the structure analysis warrants the chemical conclusions drawn from it.

"Contemporary Small Molecule Crystallography: Problems, Programs and Pitfalls" was moved to a larger room half-way through the day, as the audience increased in size as the day went on. The final open discussion session at the end of the day ran beyond the official closing time and had to be called to a close because of the hour. A large number of opinions were expressed regarding the publication process and journal policies in evaluating structure determinations. The formal discussion session spilled over to informal discussions after the official adjournment of the session.

Larry Falvello

Workshop I - Measuring Electron Density Distributions

The direct measurement of non-spherical details found in the electron density distributions of crystals has evolved from a concept in search of an appropriate model into a technique with broad applications. Koritsanszky reviewed the close relationship of the multipole expansion model, molecular wave functions, the Hohenberg-Kohn theorem and computational chemistry; all of these are important in efforts to describe relationships of energy, structure and the chemical behavior of molecules. Lecomte explained the principles of extracting the electrostatic potential from X-ray diffraction data, illustrated the geometry-dependent behavior of the potential and provided several experimental examples. Comparison with quantum mechanics indicates good agreement and the electrostatic potential of molecular fragments is transportable if geometry is retained. Problems associated with applying these formalisms to acentric structures were discussed by Hansen, and Coppens reviewed the basic concepts of the entire discipline. The latter included the use of Bader's topological approach for analyzing the results, a method which is also widely applicable in quantum mechanics. Stevens showed how rapid data acquisition (especially with CCD detectors) removes the tedium from the experimental process while Larsen reviewed the importance and the methodology for low-temperature measurements. A description of a set of computer programs developed for electron density analysis from diffraction data (the XD package) was provided by Richter who subsequently conducted an excellent "hands-on" tutorial session to demonstrate the process. The local committee performed an exceptional feat of relocating this workshop at the last hour to provide access to UMSL's Sun workstation teaching laboratory. The advantage of these facilities for the tutorial far offset the minor inconvenience of traveling to the UMSL campus and Nigam Rath and Lee Brammer are commended for their role in helping nearly 50 visitors navigate. Rath was also indispensable in setting up facilities for the tutorial session.

Fred Ross

Charge Density Analysis into the 21st Century

In coordination with the workshop on Measuring Electron Density Distributions and since the first book covering this topic has recently appeared (see Polycrystal Book Service, P. Coppens, author), it seemed timely to ask where this methodology is headed and what new developments might be anticipated. Ed Stevens opened speculations to an overflow audience (>150) by defining "Quantum Crystallography" where molecular wave functions are obtained experimentally to provide input for theoretical calculations. He and Coppens (following lecturer) indicated that significant improvements in computing power and in instrumentation (synchrotrons, CCDs, etc) permit considerably more ambitious studies - such as measuring temperature dependence or time-resolved studies of dynamic phenomena. However, Coppens emphasized that much more work is needed to establish the veracity of rapid data acquisition methods in charge density analysis. Koritsanszky introduced formalisms for rigid-body multipole refinement which helps deconvolute thermal motion from the charge density distribution. This also produces fewer variable parameters, more stable refinements, better estimates and more accurate predictions. Flensburg contributed a nice comparison of topological maps obtained by refinement of diffraction data with those from theoretical computation (CRYSTAL95) , while Madsen reported reliable transferability of fragment electron densities in methylammonium deuterium maleate. The latter work produced algorithms for the identification of critical features in the topological maps. Similar transferability of fragments in polypeptides was discussed by Jelsch along with the development of a database for such information and application to a polypeptide of MW=1066. Such transfers do not appear to alter bond lengths, but reduce standard deviations and R-factors. Abramov's contribution on secondary interactions in ionic crystals initiated a lively discussion on the relationship of (3-1) critical points to the existence (or absence) of a chemical bond. Poster presentations included a study of a barbituric acid derivative as part of an effort to develop a model for the drug receptor site and several studies of metastable photogenerated excited states. It appears further application to short-lived states, studies of larger and more complex systems, rigid body refinements and large-scale transfer of group scattering behavior will be commonplace as we enter the millennium. Widespread acceptance of charge density analysis as a precursor to meaningful quantum chemistry will take a little longer.

Fred Ross

Solution and Refinement from Powder Data

The development of techniques to solve structures ab initio using powder diffraction data is one of the most exciting aspects of contemporary crystallography. More than 300 structures of increasing complexity have been solved so far. The process still is, and will continue to be, nonroutine - if only because it asks a lot of the experimental data. The speakers in this popular session were given enough time to speak not just about structural results, but the processes of getting them.

Armel Le Bail (Universite du Maine) provided the keynote by summarizing "special" and conventional (applying single crystal techniques to extracted structure factors) techniques of structure solution. What is now considered conventional was "special" 10 years ago. The two main reasons for failure are impure phases and data too poor for the complexity of the problem. We can expect the limits of complexity to rise; currently the most complex structure solved using powder data contains about 70 atoms in the asymmetric unit. The current state of ab initio structure solution is summarized at http://fluo.univ-lemans.fr:8001/iniref.html. The structures of a number of metal silicates and phosphates were described by Dam Poojary (Texas A&M). Important to these structure determinations were use of P31 NMR to provide local structural information, and using chemical analogies where possible. No one approach works for all problems, and the solution strategy must be tailored to the problem and the information at hand. The structure of the aluminophosphate molecular sieve AlPO-53(c) was determined by the FOCUS method, as described by Rich Kirchner (Manhattan College). The FOCUS method incorporates chemical information used in model building into the structure determination process, and combines automatic Fourier recycling with a specialized framework search specific to zeolite structures.

Computational chemistry (real space) tools have advanced enough to be useful in structure solution. The structure of 2,6-naphthalenedicarboxylic acid was solved by adjusting the packing of the molecules in a known unit cell to minimize overlap and form hydrogen-bonded chains, and the structure of its dimethyl ester was solved by simultaneous monitoring of real-space packing energy and reciprocal space matching of the observed and calculated powder patterns (Jim Kaduk, Amoco). Bill David (ISIS) described three strategies - variable count time, Bayesian extraction methods, and the exploitation of thermal expansion - to remove the effects of peak overlap, and obtain accurate extracted structure factors. In real space model building, the best initial guesses for torsion angles can be obtained by analysis of similar entries in the Cambridge Structural Database. Clive Freeman (Molecular Simulations) summarized the variety of molecular simulation techniques available for use in solving structures, and illustrated their application to oxide, framework, and organic structures, as well as their use in completing a partial structure model and solving a structure by simulated annealing techniques. The majority of structures solved so far using powder data are framework or non-molecular solids. Since the effective resolution of powder data is usually 1.5-2.0 Å, conventional strategies usually fail when applied to powder patterns of organic molecular solids. Maryjane Tremayne (University of Glasgow) presented two ways of overcoming these problems - the maximum entropy-likelihood method (MICE), and Monte Carlo methods (OCTOPUS). These methods use knowledge of the molecular structure to assist in solving the crystal structure. It is possible and fruitful to combine these two methods, using MICE to obtain rough structures, followed by Monte Carlo techniques (using the whole molecule) to better define the possible structures.

Jim Kaduk

XAFS Studies of Complex Materials

A one-half day workshop on XAFS Studies of Complex Materials was held on Wednesday July 23. The workshop was sponsored by the International XAFS Society and the newly formed IUCr Commission on XAFS approved at the last IUCr meeting in Seattle, WA. The workshop was organized by Dale Sayers of North Carolina State University. Part of the purpose of the workshop was to further develop the relationship between the crystallographic community and that portion of the XAFS community interested in the atomic structure of materials. The thrust of the workshop was to show how XAFS can be applied to complex materials or in situ studies where standard crystallographic methods may be difficult or impossible.

The speakers at the workshop included John Rehr of the University of Washington who demonstrated how ab initio calculations using the improved code FEFF developed by him and his colleagues can be used to analyze XAFS in complex materials. The code has now been extended to calculating DAFS spectra and anomalous scattering factors. Recent developments in their ability to calculate multiple scattering paths have led to significant improvements in their ability to calculate XANES spectra and to get an absolute determination of the Fermi level. Dale Brewe of Pacific Northwest National Laboratory spoke about using tapered capillaries to do microXAFS and microdiffraction. Spatial resolutions of one micron and less have been achieved, and with the new third generation sources such as the Advanced Photon Source, flux densities can exceed 1010 ph/sec/micron2. This will allow studies of complex multiphase materials. The problems of fabricating and aligning capillaries and the characterization of capillaries at the NSLS were described. William O'Grady of the Naval Research Laboratory presented results on in situ studies of Pt/Ru alloy fuel cell electrodes operating under electrochemical methanol oxidation conditions. By being able to directly observe the structural changes around both the Pt and Ru atoms under operating conditions, important new information can be developed to optimize the structure of the electrodes and improve the operation of these important energy sources. Mark Antonio of Argonne National Laboratory discussed in situ studies of some rare earth phosphotungstate anion complexes which are interesting intermediate valence materials with potential catalytic applications. His particular focus was on the change of valence of Eu at open circuit and at significantly reducing potentials which were observed directly in a specially designed electrolysis cell. Finally, Boyan Boyanov of North Carolina State University described recent experiments on the structure of thin metal films down to submonolayer thicknesses deposited and annealed on SiGe semiconductor alloy substrates. The samples were prepared using MBE both at a laboratory at North Carolina State University and using a new on-line MBE system at beamline X-11 of the National Synchrotron Light Source. Results on Ti and Co films were shown and their implications as possible electrical contacts were discussed. In particular, in situ studies were conducted on 0.7 and 1.7 monolayer samples of Co on Si0.79Ge0.21 films which gave new insight about the nucleation of the metal contacts in these systems.

Dale Sayers

Atomic Dynamics

True glasses were the subject of two of the three symposia sponsored by the Amorphous Materials SIG. These symposia attracted a broad mix of interests, ranging from theory to solid state physics and chemistry to instrumentation. The presentations illustrated the critical nature that diffraction-based techniques play in the study and development of amorphous materials, and also showed where the current fertile areas of research lie.

The session on Atomic Dynamics was organized by Professor Josef Zwanziger of the Indiana University Chemistry Dept., and was focused on the motion of atoms in glass. Molecular dynamics simulations formed an important component of the talks in this session, ranging from simulations of a theoretical glass, namely quenched Lennard-Jones fluid, to highly realistic models of germanium selenide based on ab initio molecular dynamics. Simulations of model glasses were used to probe the universal low temperature properties of the glassy state, and in particular the tunneling modes believed to give rise to the anomalous specific heat observed in essentially all glasses. Chaos, and how it can be quantified, in glass-forming melts formed the topic of a second presentation, as studied again by molecular dynamics simulation of silicate liquids. Experimental probes of dynamics included inelastic neutron and Raman scattering, which were used to study non-oxide chalcogenide glasses.

The sessions closed with a brief business meeting, to discuss in part plans for next year's meeting. The SIG officers seek as always the suggestions of both members and non-members for upcoming meetings, and can be contacted through the SIG web pages at http://www.indiana.edu/~acaamsig.

Josef W. Zwanziger

Intermediate-Range Order in Glasses

The first talk in this session, "Disorder and glassy behavior in the solid phases of ethanol" was given by F. J. Bermejo and H. E. Fischer. Ethanol is an ideal system for studying glassy behavior, since both orientational and positional disorder can be induced: the two glass transitions (Tg) occur at about the same temperature. The structure factors for the structural glass (SG) and orientational glass (OG) are very close: the main difference is that oscillations in D(r) are damped out more quickly in the glass. The vibrational spectra in the boson peak region are also very similar in the orientational and structural glasses. The energy change at Tg is mostly due to orientational disorder. The conclusion is that orientational disorder is mostly responsible for glassy behavior in ethanol.

R. L. Leheny ("Search for ordering in a glass-forming liquid") addressed slowing down dynamics in the glass-forming liquid propylene glycol. Dielectric spectroscopy suggests that the relaxation time is singular at some temperature T0 ~ 120K. But, experimentally the system undergoes a glass transition at Tg ~ 160K. The temperature dependence in the liquid was therefore studied to look for evidence of this behavior. Is there a new length scale associated with slowing dynamics? Neutron diffraction was carried out using small- and wide-angle scattering at IPNS. No evidence for a new length scale, down to 20 nm, was observed. However, substantial orientational order is observed in the liquid, which increases as the glass transition is approached. This is due to changes in 1) density and 2) intermolecular hydrogen bonding. The former, but not the latter, may connect with the slowing dynamics.

"Intermediate-range order in fast-ion coordinating glasses" was the next paper presented by C. Cramer, M. Buscher, D. L. Price, and M-L. Saboungi. Fast-ion conducting glasses (FICG), often AgI-containing network glasses, have a d.c. conductivity ~10-2 ohm-1 cm-1 at RT. Normal network glasses have conductivities ~5 orders of magnitude lower. Structurally, FICG have a diffraction peak at very low wave vector Q (VLQP). This is not due to microcrystalline AgI - like regions, as previously suggested. Measurements are reported here for (AgI)x(Ag2SeO4) 1-x glasses. The glasses and liquids have a VLQP at Q = 0.74 Å-1 which is not seen in crystalline Ag2SeO4 or partly crystallized mixed material. It may be associated with AgI-rich and AgI-poor regions. Conductivity spectra were measured by impedance microwave and FTIR spectroscopy. Two relaxation times, due to nonlocalized and localized processes, were found. These are most likely formed in the two different regions indicated by the structural study.

P. Vashishta, R. K. Kalia, J. P. Rino, G. Gutierrez, and I. Ebbsjö authored the next paper, "Large-scale computer simulations of glasses". They carried out molecular dynamics simulations of glasses with parallel architecture computers and investigated the pressure and temperature dependence of SiO2 , the brittle-to ductile transition in SiO2 and multiple length scales in nanophase ceramics.

"Structural Assembly in Glass Forming Melts" was the paper presented by R. Youngman, J. Kieffer and J. D. Bass. Brillouin scattering measurements were made with a high-temperature furnace, room temperature to 1600 deg C, with controlled oxygen concentration. Shear peaks were observed which become highly damped at low temperature. The loss modulus in B2O3 gives a peak at 500 deg C which correlates well with the viscosity, due presumably to structural rearrangements above Tg. MD computer simulation shows a bond-swapping mechanism. GeO2 and B2O3 show a change in loss modulus at Tg, not SiO2 (which shows a change at much lower T, however, due to a bond-flipping mechanism).

The final paper "Intermediate-Range Order in Tellurite Glasses due to Modifier-Ion Clustering" was given by J. W. Zwanziger. TeO2 is a conditional glass former. The lone pair on the Te confers a large nonlinear optical susceptibility. In the crystal, TeO2 has a trigonal bipyramid structure with all bridging O. Na2TeO4O9 is a layered compound with tellurite layers. K2TeO4O9 is dominated by 12-membered rings. In Na4Te4O10, the network cleavage is essentially complete. Na2TeO3 has TeO32- ions with coordination down to 3. The number of non-bridging oxygen in the glasses depends on the concentration of M+ and on the ion (can be 1, 1.5 or 2, while it's always 1 in silicates). NMR shows an increase in M2 at 20 mole % of Na2O. Neutron diffraction was carried out on M = Na, Li (incl. zero lithium) loaded glasses. The Extended-Range Order Peak at 1.5 Å-1 occurs with heavier alkalis. The O-Te-O bond angle distribution peaks at 90 deg, consistent with a lone pair on the Te.

David Long Price

Disorder in Maerials: Highly Disordered Crystals

Until recently the research worlds of crystallography and of amorphous materials were distinct and separate. In crystallography, determining the position and intensity of the Bragg peak was the main task. Bragg peaks are absent in the study of amorphous materials, and measuring weak diffuse scattering and converting it into the pair-distribution function (PDF) was the goal of the research. However, the Berlin wall between the two is falling down. This is because many of the modern materials of technological interest are complex in structure, and often deviations from perfect periodicity have profound effects on their properties. The purpose of this session was to promote cross-talk between the two worlds and encourage researchers to cross the border freely.

The session started with an introductory talk by Simon Billinge (Michigan State University) who discussed the application of the PDF method to the study of crystalline solids with disorder, and the real-space analysis to determine the local structure from the PDF. As examples, he discussed high energy (60 keV) X-ray diffraction to determine the PDF of a Pt-I chain compound, and pulsed neutron scattering to obtain the PDF of manganite that shows colossal magnetoresistance (CMR). This was followed by the presentation by Vicky Nield (University of Kent, UK) who described the reverse Monte-Carlo method and its application to the study of fast ionic conductor AgI and hexagonal ice. In AgI, Ag atoms stay at the tetrahedral site most of the time (75%), and the activation energy of migration is comparable to the experimental value.

Then Mike Treacy (NEC, Princeton) described the study of zeolite materials by TEM and electron diffraction and the novel technique of variable coherence microscopy applied to the study of amorphous Si. By the latter technique, paracrystals present in the as-deposited films were differentiated from the true amorphous structure for the first time. George Kwei (Los Alamos National Lab.) described the PDF method applied to the structural study of plutonium, overcoming a multitude of difficulties from sample handling to neutron resonance. Bill Kamitakahara discussed dynamics of disordered carbon materials determined by two neutron inelastic scattering techniques: filter spectroscopy and time-of-flight spectroscopy. In particular, the local dynamics of hydrogen were found to be important in many of the carbon based materials.

Despina Louca (Univ. of Pennsylvania and Los Alamos National Lab.) described her work to determine the nature of lattice polarons in the CMR manganite by a pulsed neutron PDF study, in particular, the direct connection with the Jahn-Teller distortion. Lastly, the work of Srdan Teslic (Univ. of Pennsylvania and Argonne National laboratory, given by T. Egami) on the pulsed neutron dual space study of lead zirconate (PZ) and lead zirconate-titanate (PZT) was presented. For PZ at low temperatures, the Rietveld analysis and the PDF analysis gave virtually identical results, demonstrating the equivalence of the two for the perfect lattice, while at higher temperatures and for PZT, the real-space PDF method was able to describe the significant difference between the local structure and the long range crystallographic structure. The presentations and discussions were excellent, and the excitement of the birth of a new field was felt among the audience.

Takeshi Egami

High Pressure

Following up on the successful high-pressure sessions at the IUCr meeting in Seattle, John Parise and Charles Prewitt organized a similar session at the St. Louis meeting. Because many high-pressure talks at meetings often are dominated by the same small group of often-invited speakers, the intention here was to advertise widely with the hope that a variety of new participants with new ideas would be attracted to give talks. This was successful in that enough papers were submitted to organize a morning oral session with 10 contributed papers plus a poster group of five papers. Careful attention must be given to whether similar efforts should be continued for future ACA meetings.

In the oral session, Guoyin Shen and Yanbin Wang of the Consortium for Advanced Radiation Sources at the University of Chicago each described new diffraction facilities at the GeoSoilEnviroCARS beamlines at the Advanced Photon Source. Shen described the first experiments with the double-sided heating diamond-anvil cell, and Wang outlined plans for multi-anvil experiments. Andy Hammersley described his software for processing imaging plate data, primarily at ESRF, and Jiahua Chen reported on high-pressure/high-temperature experiments at NSLS superconducting wiggler beamline X17B, primarily on determining the state of stress in polycrystalline samples and of cation distributions. Joern Lauterjung (GeoForschungsZentrum Potsdam) described the installation and operation of a MAX-80 large-volume high-pressure facility at HASYLAB in Hamburg (see photo above). The author of the next paper on the program, Anil Singh (National Aerospace Laboratories, India) was unable to attend the meeting, and instead, short presentations were made by Jiahua Chen (T-Cup multi-anvil device), Eugene Zaretsky from Ben-Gurion University (in situ X-ray diffraction characterization of strain rate in shocked NaCl single crystals), and Osamu Shimomura (high-pressure developments at SPring-8). Ho-Kwang Mao (Carnegie Institution of Washington) told about a new method to measure rheological properties in a diamond-anvil cell that employs both diffraction along the central axis of the diamonds and in the equatorial plane. Daniel Kalantar of Lawrence Livermore National Laboratory showed how transient diffraction measurements can be made during the time a sample is impacted by a shock wave. The final two papers from the Carnegie Institution involved synthesis and crystallographic studies of dense hydrous magnesium silicates that are thought to be important as reservoirs for hydrogen in Earth's upper and lower mantles. Daniel Frost talked about compression measurements on phase D and Charles Prewitt reviewed how crystallography has played a significant role in understanding the compositional relationships and physical properties of these materials. After the last presentation on the program, Ho-Kwang Mao told the audience about a proposal to develop a sector at the APS devoted to high-pressure experiments. Currently, the only sector at APS emphasizing high pressure is part of the GeoSoilEnviroCARS effort. Because this is primarily for geoscience applications, there is substantial interest in the physics, chemistry, and materials science communities in raising enough money for a sector dedicated to high-pressure science.

Charles Prewitt

Superconductors and Related Materials

The High Tc superconductor session took place during the last day of the meeting. The goal of this session was to bring together experts from research areas of crystallography, crystal chemistry and processing science of high Tc superconductors to discuss scientific progress and problems, exchange information, and promote future collaborations. There were a total of six invited talks and one contributed talk covering subjects from crystal chemistry, crystallography, properties and processing to thin films. One of the original talks titled "X-ray Scattering Studies of the CTR Interference Fringes in YBa2Cu3O7-d Thin films" was replaced by the paper titled " Primary Crystallization Field of the 2212 and 2223 Phases in the Bi-Pb-Sr-Ca-Cu-O System".

Bill McCallum from the Ames Laboratory opened the session by discussing the effect of oxygen partial pressure on the solid solubility of Nd1+xBa2-xCu3O 7 superconductors. His group found that the oxygen partial pressure had great influence on the superconductor homogeneity region. The solubility limits govern the precipitation of second phases as flux pinning centers for improvement of critical current density. David Cox discussed the applications of synchrotron powder X-ray diffraction to structural studies of high Tc systems. Because of the superior instrumental resolution and peak- to-background ratio of this method, many subtle features may be revealed. Examples were given of recent studies of systems that involved phase transitions at high pressures and low temperatures, applications of resonant scattering techniques, and analysis of a complex multiple phase system. The importance of texture and grain boundary misorientations on critical current densities in high Tc superconductors was discussed by Amit Goyal from Oak Ridge National Laboratory. General results of studies of grains of high-Jc Bi-2223 powder-in-tube, Tl-2223 thick films, and melt processed Bi-2212 thick films suggested that long-range conduction in polycrystalline superconductors utilizes connected networks of low energy boundaries. This forms the basis of the development of the long range biaxially textured, flexible metallic substrates for epitaxial deposition of superconductors, which are referred to as the rolling-assisted-biaxially-textured-substrates (RABiTS). The superconductor films prepared using the RABiTS technique give rise to films with excellent superconducting properties. Winnie Wong-Ng of NIST discussed the location of the primary crystallization fields of the 2212 and 2223 high Tc superconductor phases in the multi-component (Bi,Pb)-Sr- Ca-Cu-O system and showed examples of the importance of the quantitative information of this field for growth of single crystals.

After a brief coffee break, Dick Harlow of the DuPont Company, in his presentation, stressed that little "Tilts" mean a lot in correlating structural phase changes with Tc in the La2CuO4 system. It was through the detailed studies of structural transitions in various compounds ( i.e. La2-x-yReySrxCuO 4, and La2-xBaxCuO4) that a microscopic view of high Tc superconductivity could be established. Omar Chmaissem of Argonne Laboratory discussed the evidence for multiple defects in Tl2Ba2CuO6+d (Tl-2201) and HgBa2CuO4+d (Hg-1201) superconductors observed by neutron powder diffraction. Defects were found to control the properties in each family of compounds. For example, in the Tl-2201 family, the interstitial oxygen atoms in the double Tl-O layer and the Cu substitution for Tl were found to control Tc while in the Hg-1201 system, the controlling oxygen defects were found in the oxygen layers. By varying the oxygen partial pressure over a wide range during annealing, oxygen content can be used to both underdope and overdope the compound. To conclude the morning section, Roman Gladyshevskii of the University of Geneva gave a review of the crystal chemistry of Bi-based high-Tc superconductors. He systematically discussed the complex structures of the structural series Bi2Sr2Can-1Cu nO4+2n+d (n=1,2,3) based on the ideal structures, then explained how, since the real structures are non-stoichiometric, their symmetry should be lower. Both displacive and substitutional modulation render the structures extremely complicated.

In addition to oral presentations, there was one poster at this meeting. Since complex niobium oxides are considered as promising candidates for searching for high temperature superconductors, a poster describing the synthesis and characterization of reduced niobates CaMNb2O7, M=La-Ce, Sm, Gd, Dy-Lu and Y with a pyrochlore structure was given by Istomine et al. from Moscow State University. The structures of these semiconductor-like compounds which were studied using both X-ray and neutron diffraction show absence of oxygen non-stoichiometry.

It appears that at this stage of the development of high Tc superconductor research, a great deal of progress has been made but challenges still remain in the future in terms of thoroughly understanding the role of crystal chemistry and crystallography in relation to superconductivity properties and processing. The complexity of these oxides (incommensurability, phase transformation, variation of solid solution extent and defects, etc.) have indeed made the studies of high temperature superconductivity all the more fascinating.

Winnie Wong-Ng

Research Opportunities at Third Generation Synchrotron Sources

The half-day workshop was held to provide the audience with a broad perspective of the diverse types of X-ray research being planned or conducted at third generation synchrotron sources. Each of these third generation synchrotron sources is dedicated to the production of electromagnetic radiation and has been designed specifically for the incorporation of insertion devices (which greatly intensify the emitted radiation). The speakers consisted of representatives from the four major third generation synchrotrons, the Advanced Light Source/ALS, the Advanced Photon Source/APS, the European Synchrotron Radiation Facility/ESRF and SPring-8 in Japan, and R. L. Harlow from DuPont. Detailed technical information for each of the facilities and the e-mail addresses of the speakers can be obtained from their respective Web pages.

The program began with Neville Smith's overview of the ALS which provides radiation with photon energies up to 1 keV. Most of the research programs at the ALS target high-resolution spectroscopy and spectromicroscopy (e.g. an X-ray fluorescence microprobe which can provide chemical compositional maps with 30 nm spatial resolution). ALS provides one beam line for protein crystallographic research. A molecular environmental science program has been recently initiated.

Dennis Mills described the APS whose major emphasis is optimized undulator-based radiation with photon energies from 3-50 keV. The research focus areas at the APS are protein crystallography (six dedicated beam lines), X-ray scattering of liquids and amorphous materials and microdiffraction.

Peter Lindley reviewed the ESRF which provides insertion device radiation from both undulators and wigglers in approximately the same photon energy range as that of the APS. The funding of the ESRF has been shared by European countries, with France and Germany each having provided roughly 25% of the funds. Research at the ESRF has been directed toward monochromator development, protein crystallography (especially MAD-phasing), and material science.

Osamu Shimomura gave an overview of SPring-8, the latest of the four synchrotrons to come on-line (first light provided to the experimental hall on 4/23/97). Currently five beam lines are operational and seventeen others are under construction. SPring-8 will provide research capabilities in protein crystallography, X-ray scattering, and X-ray diffraction, including microdiffraction. The insertion devices used at SPRing-8 will consist of diverse designs (e.g. helical and circular undulators and a variable polarization undulator).

The final speaker of the afternoon was Dick Harlow who described DuPont's synchrotron research which emphasizes "real process" experimental conditions. Examples of DuPont's synchrotron-based X-ray research concerned the characterization of the three catalysts, AlF3-used in the synthesis of Freon substitutes, (VO)2P2O7-used in the conversion of n-butane to maleic anhydride and Pd/M/C-used to convert maleic anhydride to tetrahydrofuran (a feedstock for the monomer used in the production of Lycra). At the APS, DuPont, in collaboration with Dow Chemical and Northwestern University, is developing two beam lines for fiber diffraction, wide- and small-angle X-ray scattering and protein crystallography.

Joel D. Oliver

Transactions Symposium: Structural Informatics

The availability of crystallographic information has led the way to many new avenues of research. This symposium highlighted how this information is collected and how it is used for enabling research.

In the first part of the symposium, representatives of each of the databases summarized the features of their archives. Frank Allen, CSD, described the ever-growing small molecule database and how it can be used now as a "knowledge base" for understanding ligand interactions with macromolecules. Otto Ritter, PDB, described the continued growth of the PDB and the re-engineering of the procedures used to archive the data. Helen Berman, NDB, talked about the organization of the that archive and how it is now being used for data mining. Gary Gilliland, BMCD, showed how the information in the crystallization database can be used to develop procedures for studying new macromolecules. Finally, Paula Fitzgerald, announced the approval of mmCIF as the archival format for macromolecules.

In the first session on "Methodologies and Structure Prediction", Phil Bourne talked about how databases can be federated so that rich resources of information can be accessed. As an example, he cited the Protein Kinase Resource. Shoshana Wodak discussed structure validation and described SFCHECK which checks the structure factor data that are submitted to databases. Janet Thornton described the ways in which protein structures can be classified using CATH. Garland Marshall talked about methods for predicting affinities using information from known structures.

The second session began with John Moult describing the CASP project in which protein structures are predicted using a variety of methods and then compared with the crystallographic results. Suzanne Fortier described how formal learning procedures are used with information from crystallographic databases. Andrej Sali gave a talk about comparative modeling procedures. Steve Bryant gave the last talk in which he described the structural resources at NCBI and then described the results of threading predictions of protein structures.

Helen M. Berman and Gary Gilliland

Macromolecular Crystal Growth

A very well attended session on macromolecular crystal growth was presented by speakers on a wide range of topics determined via an internet poll. The morning's opening talk was given by Madeleine Rie-Kautt on work done with P. Retailleau and A. Ducruix. The importance of counter-ions in the crystallization of proteins was discussed. Using SAXS measurements, the effects of anions on solubility were correlated with their effect on protein-protein interactions in undersaturated solutions of lysozyme. Using a stable and inactive form of the protein subtilisin Travis Gallagher gave a very interesting talk on work he had accomplished with Qianwen Pan and Gary L. Gilliland. Modulations in growth conditions (specifically changes in salt concentration) were shown to effect the shapes of the growing crystals. He further showed why these changes in ionic strength had the effect which they did on crystal shape by presenting crystal contacts in the protein structure. Monochromatic X-ray topographs acquired at CHESS were used to characterize the perfection of lysozyme crystals grown under nearly uniform and time-varying crystallization conditions. Robert E. Thorne, in collaboration with K. Finkelstein and I. Dobrianov, presented this very interesting visualization of lattice strain analysis. Means to reduce the appearance of these lattice strain effects were suggested.

John M. Rosenberg presented a very informative overview of a software package he is developing for protein crystallization protocol design. The computer did crash (literally falling to the floor minutes before the presentation), but recovered in time for the talk. This demonstrated not only the hardiness of the program but the steel nerves of John who calmly recovered his presentation. The work was done in collaboration with Patricia A. Wilkosz, K. Chandrasekhar, Devika Subramanian, Daniel Hennessy and Bruce Buchanan. The highly interactive software has voice recognition capabilities. An impressive demo of the program, showing off some of its features, was given as part of the presentation.

Marc Pusey's presentation on the results of microgravity macromolecular crystallization experiments was also a plea for the publication of more microgravity produced crystal structures. Both the number of macromolecules being crystallized in microgravity and the experimental protocols available to investigators are greater than ever. Investigation of crystal structure results from microgravity experiments was difficult due to the lack of published data. Fred Dyda presented work on the crystallization of integrases using molecular biology to improve solubility and order of the protein. This work was done with Alison Burgess Hickman, Tim Jenkins, Shani Waninger, John Scocca, Robert Craigie, and David R. Davies. The low solubility and aggregation of the protein even at low concentrations made more traditional crystallization methods unsuitable. Domains were identified by limited protease digests and multiple runs of single point mutations produced a version of the catalytic domain which was active and crystallizable. The application of molecular biology to protein crystallography shows a very powerful combination of the two sciences.

Kim M. Gernert presented work accomplished in collaboration with David C. Richardson, Jane S. Richardson and Christopher Davies that also showed the power of combining molecular biology with protein crystallography. It focused on mutations in a crystal contact of cytochrome B562. Mutations of the amino acids important for contacts produced proteins which generally crystallized under different chemical conditions than native material, and in different space groups.

The final speaker in the oral session was Christian Ostermeier in collaboration with Hartmut Michel. He gave a very energetic talk on F_{v fragment mediated
protein crystallization. Using two different crystal structures of bacterial
cytochrome c oxidase, the importance of the proper choice of detergent and
the critical role of antibody fragments in forming crystal contacts was
demonstrated. It was proposed that co-crystallization with antibody fragments
may become a general tool for producing well diffracting crystals of membrane
proteins.}

The Macromolecular Crystal Growth posters ranged greatly in topics. Jennifer A. Garlitz, Catherine Summers, Robert A. Flowers II and Gloria E. O. Borgstahl presented a very interesting method in which a protein (lysozyme) was solubilized and activity determined in a "molten" salt (ethylammonium nitrate). Crystallization from "molten" salts could provide interesting structural information regarding the interactions between macromolecules and a solvent other than water. The effect on protein crystal perfection of soaking macromolecule crystals in solutions other than those from which they were produced were examined using monochromatic X-ray topography at CHESS by I. Dobrianov, K. Finkelstein and R. E. Thorne. Time evolution of lattice strains and defects could be observed as they related to changes in solution conditions. The effect of g-jitters (caused by astronaut exercise and jets firing on the orbiter) in microgravity crystallization experiments of lysozyme were examined by E. H. Snell, T. J., Boggon, J. R. Helliwell, M.E. Mosokowitz, and A. Nadarajah. Using CCD video monitoring they show that growth spurts of the crystals correlate with g-jitter aboard the NASA space shuttle.

Statistical analysis of the Biological Macromolecular Crystallization Database 3.0 was conducted by Robert G. Farr Jr., and Cleopus T. Sumudzi. Clustering techniques showed trends in the crystallization parameters for several classifications of macromolecules indicating potential starting conditions for crystallization experiments. The use of ultrasound, vortex mixing, and tissue grinders to disrupt crystals for use in crystallization of macromolecules from serial dilute seed stock was presented by Joseph R. Luft and George T. DeTitta. Kristofer J. Thiessen's presentation examined the use of agarose gels in combination with microgravity for the crystallization of thaumatin. The gel protects crystals during reentry.

The use of fusion proteins to study the structure of biologically active peptides of ten to forty amino acid residues (which are notoriously difficult to crystallize) was presented by Eric J. Haas, Huo Wen, Charles R. Ross II, Fred W. Wagner and John J. Stezowski. They reported the successful use of human carbonic anhydrase II as a vehicle for crystallization of the last twenty four residues of eel calcitronin. The fusion protein crystallized isomorphous to carbonic anhydrase II and diffracted to 1.8 Å resolution, the peptide showed some disorder in the crystal lattice. Gerald Stubbs, Kelly Plonk, Greg Ferrell, Jack Smith, and Hong Wang investigated the special problems of filamentous virus crystallization including degradation by proteolysis and helical aggregation. They presented conditions for stabilization of the proteins and a number of crystallization conditions.

P. R. Pokkuluri, D.-B. Huang, R. Raffen, P. Wilkins Stevens, F. J. Stevens and M. Schiffer presented their investigation into how metal ions (specifically calcium and zinc) can promote crystal formation by taking part in crystal contacts for two immunoglobulin light chain variable domain structures. The X-ray structures of two crystal forms of monocyte chemoattractant protein 1 (important components of the immune system) were presented by Jacek Lubkowski, Lluis Boque and Grzegorz Bujacz and Alexander Wlodawer. Large amounts of the NF-p50/p65 heterodimer, from a family of transcription factors that mediate vital cellular processes, were produced, and crystallization with a few DNA targets containing the binding site were reported by F. Chen, D-B. Huang and G. Ghosh.

Cathy M. Schellert, Yue-jin Huang, Richard Komuniecki and Gloria E. O. Borgstahl presented the purification and crystallization of the anaerobic isoform (type 1) pyruvate dehydrogenase E1 heterodimer. Purification and crystallization trials of recombinant Replication Protein A were presented by Jeffrey F. Ohren, Leigh A. Henrickson, Marc S. Wold and Gloria E. O. Borgstahl. Purification and crystallization trials of recombinant Human Homologous DNA Recombination and Repair Protein RAD52 were reported by Wasantha Ranatunga, Mis S. Park and Gloria E. O. Borgstahl.

Joseph R. Luft and George T. De Titta

Computational Methods Session

Everyone, it seems, still wants to know what the latest and best methods are for macromolecular crystal structure determination. The session on Computational Methods for Macromolecular Crystallography was packed with crystallographers hoping for a glimpse at the future. The first set of speakers talked about ways to improve structure solution. Eric de la Fortelle (MRC, Cambridge) led off the session with an exciting description of SHARP, a program that takes MIR and MAD heavy atom refinement and phasing to its limit using a Bayesian approach throughout. This session chair (Los Alamos) then described SOLVE, a program that can solve MIR and MAD structures automatically, starting with raw data and basic information about the crystal. Next, Jan-Pieter Abrahams (MRC, Cambridge) gave a theoretical description of "solvent-flipping", showing that it works well in solvent flattening because it reduces model bias.

A second set of speakers talked about how refinement procedures might be improved. Rob Grothe (Washington Univ., St. Louis) gave an outsider's view of the refinement problem, showing a complete Bayesian framework that (with supercomputer assistance) could be applied to refine macromolecular crystal structures. Raj Pannu (Univ. of Alberta) showed a practical implementation of a Bayesian approach in which maximum likelihood refinement was improved even further over conventional refinement by including experimental phase information. Jennifer Kelly (UCLA) talked about how one might include anisotropic thermal parameters without increasing the number of parameters too dramatically by using local anisotropic parameters described by a Fourier series. Finally Zhi Chen (Florida State) talked about how real-space refinement can be used with molecular dynamics to increase the convergence radius of macromolecular refinement.

The last pair of speakers in the session described how we can evaluate the results of macromolecular refinement. Focco van den Akker (Univ. of Washington) showed an automatic procedure based on difference maps that identifies parts of a macromolecular structure that are unlikely to be correct. Dusan Turk (Univ. of Ljubljana) finished off the session by describing how "kicked" omit maps (where atoms in the structure are randomly displaced before calculating an omit map) provide a very fast way to obtain a reduced-model-bias map.

A very diverse poster session on computational methods accompanied these talks. Posters ranged from graphical user interfaces (John Irwin and Eric de la Fortelle, MRC; Akihito Yamano and Yukiteru Katsube, Rigaku Corp.) to extending the power of Shake-and Bake (Charles Weeks, Russ Miller, and Herbert Hauptman, Hauptman-Woodward Medical Research Institute) to developments in automated map interpretation (Thomas Oldfield, Molecular Simulations, Inc.), with everything in between. One particularly exciting poster described for the first time the theory and application of the FFT method for auto-indexing oscillation images (Ingo Steller, Robert Bolotovsky and Michael Rossman, Purdue).

Overall, the computational methods session and posters were a big success. There appeared to be a lot of interest in having another session of the same type next year.

Tom Terwilliger

Ultra High Resolution Structures and Cryocrystallography

The ultra high resolution structures and cryocrystallography session was opened with a talk on improving data quality by annealing flash cooled crystals. This was given by Joel Harp from the Oak Ridge National Laboratory. By transferring the flash cooled crystals back to cryoprotectant and then refreezing the mosaicity could be reduced dramatically. Examples were given of a nuclesome core particle, a histone octamer and lysozyme. An excellent detailed poster covering the work was also presented. Tsu-yi Teng from the University of Chicago presented a talk on the structures of carbonmonoxymyoglobin and its photoproducts at cryogenic temperatures. The structures observed by Teng, Schlichting and Hartmann were compared and differences explained by the different photolysis protocols causing an unbound ligand to migrate along the reaction coordinate. Each study also used different cryoprotectant protocols which appeared to have little effect on the resulting structure. Sean Parkin from Lawrence Livermore National Laboratory gave the last talk before the coffee break, presenting a comprehensive guide to practical cryocrystallography and a wonderful cornucopia of laboratory developed and tested tools. He illustrated the application of these tools and techniques to atomic resolution studies of several proteins.

Mitchell Miller from the University of Houston presented details of the data collection at the DESY synchrotron and preliminary refinement details of the 53 kDa endonuclease from Serratia marcescens. The difficulties of collecting data to 0.92 Å from a protein of this size were highlighted: multiple pass data collection strategies are necessary to sample the full dynamic range of the diffraction, emphasizing the need for fast readout detection systems. Martha Teeter from Boston College presented details of the latest results from the small protein crambin. Diffraction data have been collected to 0.67 Å resolution using short wavelength X-ray radiation. A refinement with 59000 unique reflections for the 449 atoms is currently underway. Peter Kuhn from Stanford Synchrotron Radiation Laboratory gave details of the data collection optimization used to collect highly complete data to 1.25 Å resolution from the 50 kDa B5 pentamer of Cholera toxin. The refined structure will be used to study the receptor binding properties of various mutants, a colorful and informative part of the presentation resulted from work by Ethan Merritt (University of Washington) incorporating the thermal ellipsoid data into Raster 3D.

The session hosts would like to express their thanks to the speakers and the poster presenters not only for the huge amount of work put into obtaining the results but also the detailed and extensive preparation which resulted in a series of very interesting and informative presentations.

Eddie Snell and Ashley Deacon

Nucleic Acids and Nucleic Acid-Protein Complexes

This Tuesday afternoon session began with a story of ends; the ends of chromosomes. Martin Horvath described the structure of the telomere binding protein from O. nova complexed with a twelve nucleotide fragment of DNA. The structure contains an impressively long arrangement of stacking interactions that involve the protein and the DNA and put the DNA in a very non-helical conformation. This structure highlights the importance of stacking interactions. The next two talks highlighted the important role of metal ions in RNA structures. Carl Correll described the structure of the 62 nucleotide nuclease resistant domain of 5S rRNA from E. coli. It contains a 'metal zipper' which produces great distortions in groove widths. Carl also gave us cloak-and-dagger tips concerning the use of ricin and umbrellas. Jamie Cate went on to describe several metal binding sites in the 160 nucleotide Tetrahymena group I intron P4-P6 domain where anomalous scattering has been used to identify the types of ions present. The contrast between RNAs folding around a metal-based core and proteins folding around a hydrophobic core was emphasized.

The thread then returned to DNA with talks by Sylvie Doublie and Michael Sawaya on DNA polymerases. Several different complex structures are providing us with a detailed structural understanding of how polymerases can maintain high fidelity while accommodating all the necessary base pairs. Loren Williams described how drugs can adopt different binding modes to DNA. Chul Hee Kang and S. Raghunathan described the structures of single-stranded DNA binding proteins and promised that structures with DNA bound are imminent. The final talk of the session was by Cele Abad-Zapatero who described the structure of ermC'; an RNA methyltransferase which confers antibiotic resistance to bacteria.

The posters contained a broad range of topics. Gary Hu presented a provocative poster that investigated the statistical significance of conformational parameters of DNA; Fourier truncation (i.e., limited resolution) apparently affects the structure as much as sequence and lattice forces. New crystals and/or structures were reported for several other systems: Rep DNA helicase, RbsR repressor protein, I-CreI, a fragment of the influenza virus NS1 protein, influenza virus matrix protein M1, human topoisomerase, DNA polII, colicin E3 immunity protein, NF-kB proteins p50 and p65, B. stearothermophilus DNA polymerase with DNA, hepatitis C virus RNA helicase, and several DNA-drug complexes. Barbara Golden presented her "Golden" Sparse Matrix for RNA crystallization and progress on crystallizing the entire Tetrahymena group I intron (diffraction is now almost to 3.5 Å). Clearly, many good things are in store for next year's meeting in Washington.

Craig Kundrot

Macromolecular Structure and Mechanism

This scientific session organized by the macromolecular SIG produced a typical abundance of structural results, covering virtually all fields of molecular biology and biochemistry. Of particular note, within both the talks and posters, are two increasingly strong themes. First, MAD techniques, using a variety of scatterers, are being used with increasing frequency to produce accurate initial phase estimates for large proteins. Second, the current explosion of structural information is being extended to increasingly complex assemblies of protein and nucleic acid chains.

\The presentations reflected the impact of structural biology across most biological disciplines. The presentations represented recent results in the fields of structural proteins and protein-protein interactions, enzymatic catalysts, structural immunology, and protein dynamics during activation and assembly. Structures reported included the long-awaited structure of the fibrin D-fragment and cross-linked D-D complex (Glen Spraggon), bound with the primary polymerization peptide from its partner (the E-fragment). This complex forms the structural core of human fibrin polymers. These structures, consisting of three chains of total mass 730 kD per fragment, illustrate many of the interactions that take place to form and stabilize blood clots, and also allows detailed characterization of many known fibrinolytic mutations. Complementing this presentation were a pair of talks on the adhesin collagen-binding domain (J. Symerski) and the actin-crosslinking domain from human fibrin (Steve Almo). Both of these talks also demonstrated the biomedical importance of understanding structural protein-protein interactions (and their disruption by pathological agents and congenital defects) for pathogenic forms of septic arthritis and muscular dystrophy, respectively.

Two presentations on the recent structure determination of important enzyme catalysts followed. The structure of peptidylglycine a-hydroxylating monooxygenase PHM (Sean Prigge) demonstrated the use of MAD data collected at the absorption edge of the enzyme's intrinsic, catalytic copper ion as the sole source of experimental phases and allowed the initial characterization of potential catalytic residues in the hydroxylation reaction. This was followed by a description of the structure of the catalytic core of adenylyl cyclase (Vibha Rao), which plays a central role in signal transduction by synthesizing cAMP in response to G-protein coupled hormone receptors. Of particular interest in this latter talk were ongoing attempts to predict and simulate the structure of a modeled Gsa molecule docked onto the cyclase, to study its interaction with the G-protein and to design mutagenesis experiments that probe G-coupled signaling in greater detail.

Two talks demonstrated the importance of structural biology in the field of immuno-recognition. The interaction of the cyclophilin A protein (a receptor of the immunosuppressive drug cyclosporin A and an inhibitor of the calcineurin phosphatase) with a fragment of HIV-1 Gag protein was described (Yingdong Zhao). The cyclophilin protein (and presumably its interaction with Gag) is required for viral assembly and infectious activity of HIV-1, possibly by providing a chaperone-like function for the viral protein. This talk was followed by a report on progress in describing the structure of the MHC/T-cell receptor complex (Christopher Garcia). A particularly impressive focus of this talk was the description of the role of individual CDRs in MHC/peptide recognition, and the exciting possibility of future co-crystallization experiments with other components of the recognition complex.

The final talk presented a crystallographic study of an activation intermediate during activation of gastricin, an aspartic acid proteinase. This transient structural and functional intermediate was isolated and stabilized by pH trapping, purified, and then crystallized. The subsequent structure determination indicates the growing role of X-ray crystallography for visualizing large-scale biochemical events in a time-dependent manner.

The accompanying poster session provided an impressive collection of studies for a wide collection of disciplines, including allosteric regulation, immune recognition, enzymatic catalysts, and signal transduction proteins and interactions. Of particular interest in these presentations was a series of studies from several labs on the allosteric transition of hemoglobin, which collectively combined crystallographic analyses with solvent trapping, mutagenesis, spectroscopic analysis, and novel ligand effects to continue mapping binding pockets, conformational motions and diffusion pathways in this molecule. These studies clearly indicate the continued importance of well-characterized model systems for increasingly detailed and quantitative analysis of structure/function relationships. Additionally, the structure of glutamine PRPP amide transferase, complexed with substrates and nucleotide regulators, was reported (Joseph Krahn). For this structure, which displays a clear substrate channel that is open when the GTP regulator is not bound, seleno-methionine derivatives were successfully utilized for MAD phasingan outstanding achievement involving the determination of 22 selenium positions in the asymmetric unit to phase maps covering over 1000 amino acids for the functional enzyme dimer. This structure, which was solved with the use of direct methods to deconvolute the heavy atom positions, indicates the potential wave of the future in structure determinations.

Barry Stoddard

Review of Enzymes and Proteins of Pharmaceutical Interest (Posters 42-77)

As I made my way though this series of 36 posters presented under Enzymes and Proteins of Pharmaceutical Interest, my first reaction was "wow". The scope of ailments and diseases being studied was impressive. Topics ranged from the common cold to HIV-related research. Other hot topics, besides HIV-related research, dealt with coagulation, inflammation, and cancer. Several additional human maladies such as bacterial, fungal, and viral infection, amyloidosis, arthritis, obesity, and high cholesterol were also addressed. It is safe to say that everyone will seek some therapy for one or more of these afflictions at some point in his or her life. My growing stack of booklets from past ACA meetings serves as reminder that none of us are getting any younger (just wiser). It was encouraging to see that other laboratories and companies are working in areas where I am not. It was also encouraging to see evidence of competition between research groups in certain areas. As Bob Sweet and Steven Sheriff can attest, I managed to get terrible food poisoning during a synchrotron trip to X12C. Be assured, at the time, the fact that the prescribed antibiotic was made by another company was not a concern! Maybe some of these posters will lead to treatments that will make a difference for someone in your family, a former mentor, a fellow crystallographer, or even yourself. After all, the real impetus behind this collection of work is to improve the quality of life for everyone. My second, but related, reaction was an appreciation for the volume of the work being presented. Sure, I spent some late nights for a week or so and put together a poster that summarized two years of work on a few 8x11 graphics. But many of these posters left me with the impression "that was a lot of work". I was not only impressd by the amount of work, but by looking at the dates on the related references, also the pace at which it is being done.

Finally, a few interesting statistics for those who might want to look for and analyze trends. The posters reflected the work of approximately 40 different groups with roughly an equal mix of academic and industrial laboratories. Approximately 25% of the posters involved collaboration between academia and industry.

Herbert Klei

Complementing Crystallography with Other Biophysical Approaches

This Symposium focused on the correlation of spectroscopic and thermodynamic data with structures. Spectroscopy can provide details about bonding and electronic structure that are powerful adjuncts to X-ray analysis, and thermodynamics yields clues to the nature and strengths of interactions observed in crystal structures.

Spectroscopic methods can be adapted to permit measurements on single crystals, allowing detection and analysis of ligand binding and of chemical reactions. With suitable averaging of absorbances recorded with plane-polarized incident light, spectra comparable to those observed in solution can be derived. Direct microspectroscopy using single crystals is particularly appropriate for (but not restricted to)the large family of proteins with organic or inorganic prosthetic groups. For example, Gian-Luigi Rossi and co-workers have determined the oxygenation curves and Hill coefficients for crystals of hemoglobin A and for a series of crystalline mutant hemoglobins. In a number of cases, crystalline deoxyHb binds oxygen non-cooperatively (n=~1) and with p1/2 characteristic of T-state, confirming the notion that restraints on quaternary rearrangement of the hemoglobin molecule, provided by the crystal lattice, should suppress cooperativity. In collaboration with Rossi, Scott Mathews and co-workers have examined electron transfer within a crystalline complex of three proteins - methylamine dehydrogenase, the Type I "blue copper" protein amicyanin, and a c-cytochrome. Reducing equivalents from methylamine bleach the TQQ cofactor of MADH and in turn are transferred to amicyanin and to cytochrome, and the pH dependence of the electron distribution can be explored. Intermolecular electron transfer appears to be precluded: electron transfer is essentially blocked by substitution of apo-amicyanin in the complex. A familiar caveat in"crystal chemistry" experiments is that reaction rates may differ from rates found in solution.

Determination of the precise geometry of metal-ligand clusters in proteins is problematic for crystallographers. Raman spectroscopy has provided essential data on metal bonding, particularly in heme and copper proteins. Blue (Type I) Cu proteins like azurin or amicyanin are a good illustration, as reviewed by Roman Czernuszewicz. Raman spectra from several labs have shown bonding of the axial methionine to be exceedingly weak or absent in azurins; Czernuszewicz has also determined the effects of ligand substitution on thiolate-Cu bonding in Type I Cu proteins by Raman spectroscopy in cases where differences cannot be detected by comparisons of structures per se.

Correlations of buried surface area with energies have been a useful guide in studies of the interactions of proteins, but the energies associated with ligand binding or hormone receptor interactions are not easy to determine by inspection of structures - what you see is not necessarily what you get. A striking example is found in the interactions of human growth hormone (hGH) with its receptor and with the prolactin receptor. Tony Kossiakoff summarized the pioneering studies of these systems, carried out at Genentech. As measured by alanine-scanning mutagenesis, subsets of the residues buried in the hormone-receptor interface (hot-spots) account for most of the free energy of interaction, and replacement of some of the other interface residues actually increases binding affinity. Selection for binding affinity, carried out by combinatorial mutagenesis using phage display techniques, leads to an hGH that binds its receptor with a Ka 400 times that of wild type. Structural differences are induced by the multiple substitutions in this mutant and curiously, the energy of interaction is spread more uniformly among the contact residues. This result may imply that the structure of the wild type hormone is selected in part by physiological requirements other than strength of binding.

Conformational changes frequently accompany ligand binding and determination of their contributions to energies of interaction is a challenge. Interactions in the streptavidin-biotin system (Ka =~1013M-1) were described by Ron Stenkamp. When biotin binds, a flexible loop in streptavidin closes over the bound ligand. A permutation of the sequence that places the chain termini in this loop leads to dramatic decreases in affinity for biotin, of the order of 106. It is intriguing that the changes in DG resulting from the mutation are dominated by enthalpy rather than entropy terms. Bruce Palfey summarized studies of conformational changes in the flavoprotein PHBH, in which the ring of the FAD cofactor can adopt either an "in" or an "out" position, and alternation of these states is believed to be required for substrate binding. Using isothermal titration calorimetry to compare mutants and substrates that favor either the in or out positions, he has estimated the DH and DS associated with changes in position of the flavin ring. To analyze movements that occur in conformation changes, Charlie Carter has developed new algorithms to define the critical cores or units of structure that are displaced in concerted fashion and has applied the methods to assign core regions of Trp-tRNA synthetase.

A recurring theme was the role of solvents in interactions and interfaces. Changes in hydration that accompany protein-protein interactions or ligand binding contribute to the free energy, enthalpy and entropy changes associated with complex formation in all of the model systems that were discussed. In particular, from thermodynamic and X-ray studies of several peptides that bind to Src SH2 domains at different sites of varying affinity, Gabriel Waksman and colleagues suggest that water-mediated interactions must play an important energetic role in binding at the high affinity binding site.

Martha Ludwig

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Contributors to ACA St. Louis - 1997

We are grateful to the following organizations and institutions whose generous contributions helped make the ACA meeting a success.

Apple Computer

Bayer Corporation

Blake Industries

Boehringer Ingelheim, Inc.

Bristol-Myers Squibb Pharmaceutical Research Inst.

Charles Supper Company

Digital Equipment Corp.

DuPont Central Research and Development

DuPont Merck Pharmaceutical Company

Enraf-Nonius Corp.

GE Reuter & Stokes

Hampton Research

Hoffman La Roche

Int'l Union Of Crystallography

International Centre For Diffraction Data

Lilly Research Laboratories, A Division Of Eli Lilly & Co.

Merck Research Laboratories

Molecular Simulations, Inc.

Molecular Structure Corp.

NASA Goddard Space Flight Center

Nat'l. Inst. of Standards and Technology

Osmic, Inc.

Pharmacia & Upjohn Inc.

Procter & Gamble Company

Rutgers University

Schering-Plough Research Inst.

Searle

Silicon Graphics

SmithKline Beecham Pharmaceuticals

University of Missouri

Zeneca Pharmaceuticals

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Peggy M. Etter Student Travel Award
Mary McBride received a travel award dedicated to the memory of Peggy Etter. She was given a prize of $250 and a signed copy of Roald Hoffmann's "The Same and Not the Same".

Student Travel Awards - 1997

Geeta Sood, Aston U.

Ivan Dobrianov, Cornell U.

Amir R Khan, U. of Alberta

Yingdong Zhao, U. of N Carolina - Chapel Hill

Waseem Gul, U. of Calgary

Lan Huang, U. of California At Berkeley

Piotr Sliz, U. of Toronto

Monica Niederhut, U. of Pittsburgh

Huan-Wang Yang, U. of Pittsburgh

Zhenglin Hou, Iowa State U.

Sean Taylor Prigge, Johns Hopkins U.

Wilma Febo-Ayala, NIST

Eric Landree, Northwestern U.

Hong Qiu, Ohio State U.

Shyam Baskaran, Purdue U.

Sergei V. Strelkov, Purdue U.

Navraj S. Pannu, U. of Alberta

Rogerio R. Sotelo-Mundo, U. of Arizona

Zhaolei Zhang, U. of California - Berkeley

Mary T. McBride, U. of California - Davis

Benjamin Perman, U. of Chicago

Angus Mackinnon, U. of Durham

Tom J. Brett, U. of Nebraska-Lincoln

Kai Van Beek, U. of Pittsburgh

Bradley E. Bernstein, U. of Washington

Bianca Hovey, U. of Washington

Focco Van Den Akker, U. of Washington

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SADUG97 - April 17-19, 1997

The seventh annual Siemens Area Detector Users Group meeting (SADUG97) was held April 17-19, 1997 at the Georgia Center for Continuing Education on the University of Georgia campus. The organizers were John Rose and B.-C. Wang, both at the University of Georgia. There were 83 attendees, primarily from the USA and Canada.

The general topics of the meeting were: (1) hardware including Göbel mirrors, HiStar, SMART 1 and 2K, and CCD matrix and multi-detector systems; (2) data collection techniques featuring the best method(s) for data collection of both small molecule and protein structures, use of low temperature techniques and treatment of twinning problems; (3) 90s software such as ASTRO, FRAMBO, SAINT, SMART and X-GEN; and (4) demonstrations of Göbel mirrors, SMART 2K, Windows-based software and methods of handling difficult structures.

General Discussions of Area Detectors

Sue Byram (Siemens) presented an overview and prospectus of Siemens' multiwire and CCD detectors. Charles Campana (Siemens) discussed the various merits of the CCD-based SMART diffractometer: better data than from conventional diffractometers, useful data from small or weakly diffracting crystals without a rotating anode and ability to handle twinning, pseudosymmetry, etc. Two useful and informative talks about the treatment of crystal twinning in the SMART software were presented by Robert Sparks (Siemens) and Victor Young (U. Minnesota). John Rose (U. Georgia) related his experiences during the past year with the SMART 2K detector system equipped with Göbel mirrors and SAINT software. Roger Durst (Siemens) compared and contrasted the design and specifications of the various CCD systems currently available or planned. Some specifics in the design and development of the 2K CCD system as well as information about the use of Göbel mirrors and synchrotron test results were presented by James Phillips (Siemens). Ludger Haeming (Siemens) described the use of SADABS and XPREP for correction and averaging of data from Siemens' area detectors. Alan Pinkerton (U. Toledo) proposed some potential uses of CCD-based systems including the use of liquid helium coolants and studies of unstable species, such as metastable excited states and charge density analysis. Posters: Robert Sparks - Algorithms for twinned crystals; Sue Byram - What's going on at Siemens.

CCDs at Synchrotrons

Application of CCD devices at synchrotron sources was discussed by Ed Westbrook (Argonne). Richard Harlow (DuPont) described his success in the resolution of a problem structure determination of Bi4Au2O14 with a superlattice and a high absorption coefficient at conventional wavelengths. Data collected using the SMART system with synchrotron radiation at 0.185 Å have now provided a satisfactory solution.

Upgrades to CCD

Doug Powell (U. Wisconsin) and James Britten (McMaster U.) related their experiences with the upgrade of a Siemens P4 system to a CCD-based system.

Protein Crystallography

Zhi-Jie (James) Liu (U. Georgia) provided an update on the refinement of aldehyde dehydrogenase. Gary Newton (U. Georgia) gave an initial report on the study of a mutant protein of tyrosine phenol-lyase. Cory Momany (U. Georgia) described the use of self-assembling matrices and phage display in growing macromolecular crystals. Craig Smith (U. Alabama, Birmingham) related the current status of the diffractometer systems at the University of Alabama, Birmingham, as well as future additions. Enrique Abola (Brookhaven Natl. Lab.) presented an object oriented view of the PDB. Posters: Bin Hu (U. Georgia) - investigation of the best scan range and comparison of the data reduction softward X-GEN, XDS, HKL; Chia-Kuei (Edward) Wu (U. Georgia) - progress on augmenter of liver regeneration (ALR) protein; Robert Bolotovsky (Purdue U.) - auto-indexing and scaling of area detector oscillation data.

Small Molecule Crystallography

Anthony Martin (U. Toledo) described his work on the charge density studies of oxalic acid. Roger Lalancette (Rutgers U.) explained the successful resolution of a 10-year old structure problem of a ketopinic acid by the use of CCD data collected at -150 C. Robin Rogers (U. Alabama, Tuscaloosa) gave a report on establishing the CCD-based X-ray facility at U. Alabama. Posters: Kirstin Kirchbaum (U. Toledo) - l/2 contamination in area detectors; Kirstin Kirchbaum (U. Toledo) - liquid helium use on SMART CCDs; K. Chin (U. Georgia) - reinvestigation of 1,4-dimethoxy-9-isobutyltriptycene at -150 C.

Gary Newton

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Meeting Announcement

55th Pittsburgh Diffraction Conference

The 55th Pittsburgh Diffraction Conference being held at the Georgia Center for Continuing Education at the University of Georgia, Athens, GA., November 6-8, 1997. The weather in Athens during early November is beautiful and we hope y'all can come down and see us.

Conference Chair: Steven Geib, University of Pittsburgh

Local Chair: Bi-Cheng Wang, University of Georgia

Registration Fee(s):

Non-student ...................................................... $55.00

Student ............................................................ $15.00

After October 31, 1997

Non-student ..................................................... $75.00

Student ............................................................. $35.00

Reception (Thursday Night) .............................. Free

Conference Banquet (Friday Night) ................. $25.00

Bryan Craven Barbecue (Saturday Night) ........ $25.00

The registration fee for the conference includes $5.00 for PDS membership dues.

Lifetime Membership: A lifetime membership in the Pittsburgh Diffraction Society is available for a $100 tax-deductible donation!! The IRS has granted 501(c)(3) status to the Pittsburgh Diffraction Society in recognition of the charitable non-profit purposes of the organization.

Symposia:

November 6, 1997

Afternoon - Metalloproteins

Chair: Michael K. Johnson

Speakers: Karen Magnus John Peters

Jeff Bolin Matt Benning John Tainer

November 7, 1997

Morning - Metalloproteins (continued)

Speakers: Andy Karplus Dagmar Ringe

Mid-Morning - Structured Water

Chair: Loren Williams

Speakers: Martin Egli George Jeffrey

Afternoon - Structured Water (continued)

Speakers: Mary McBride Richard Harlow Qi Gao Martha Teeter Leigh Ann Lipscomb

November 8, 1997

All Day - Symposium Honoring Bryan Maxwell Craven

Chair: George DeTitta, Hauptman-Woodward Institute

Honorary Chair Speaker

Dick McMullan Bob Stewart

Joseph Ho Bob Blessing

Ed Vizzini Huan-Wang Yang

Larry Gartland Helen Berman

M. Sundaralingam Terry Sabine

Gao Qi B. C. Wang

John Ruble Li Qing Chen

John Ruble Hans Peter Weber

For further information please contact Steven Geib. Phone (412) 624-1131; e-mail: geib+@pitt.edu.

Local contacts for questions concerning lodging

John Rose or Kim Ro