W0425

SOMoRe - Search and Optimize for Molecular Replacement. Gary Wesenberg¹, Diane C. Jamrog², Yin Zhang³, George N. Phillips, Jr.¹, ¹Dept. of Biochemistry, Univ. of Wisconsin-Madison, ²MIT Lincoln Laboratory, ³Dept. of Computational and Applied Mathematics, Rice Univ.

A new molecular-replacement (MR) program called SOMoRe [1] has been developed which implements a six-dimensional optimization strategy in two steps: 1.) using only low-resolution data, a course-grid global search surveys a six-dimensional target function for regions of high model correlation 2.) the best points obtained from this first step are then used as initial points in a six-dimensional local optimization. Unlike many of the traditional MR methods based on Patterson rotation functions, SOMoRE avoids the difficulties associated with separating the rotational search from the translational search. Unlike other six-dimensional MR methods such as "Queen of Spades" [2] and "EPMR" [3], SOMoRe fully canvasses the solution space in a systematic fashion without relying on random sampling. We compare test results for several cases and demonstrate that SOMoRe is an important addition to the gamut of MR techniques. Current and future improvements to the program will also be discussed.

[1] Jamrog, D.C., Zhang, Y. & Phillips, G.N. Jr. (2003). Acta Cryst. D59, 304-314.

[2] Glykos, N. M. & Kokkinidis, M. (2000). Acta Cryst. D56, 169-174.

[3] Kissinger, C., Gehlhaar, D. & Fogel, D. (1999). Acta Cryst. D55, 484-491.

For information regarding the free distribution of SOMoRe, see: www.caam.rice.edu/~djamrog/somore.html.

Supported in part by the W. M. Keck Center for Computational Biology (NSF RTG BIR-94-13229, NLM RTG 2T15LM07093, NLM 5 T15 LM07093), NSF Grant DMS-9973339 and NIH GM64589.