W0276

Disorder in Flash Cooled Protein Crystals: Effects of Cryoprotectants and Crystal Size. J. Kmetko, S. Kriminski, Y. Kalinin, and R.E. Thorne, Laboratory of Atomic and Solid State Physics, Cornell Univ., Ithaca, NY 14853-2501, USA.

The dependence of the quality of flash-cooled gel-grown tetragonal lysozyme crystals on cryoprotectant (glycerol) concentration and crystal size was studied by conventional diffraction, X-ray topography and line shape measurements. Large (~ 1mm) crystals without glycerol showed a significant lattice constant spread, as determined by ω-2θ scans and topographs. Lattice strain decreased with decreasing crystal size and increasing glycerol concentration. Ice rings corresponding to Ih observed in uncryoprotected crystals became smeared and/or disappeared in glycerol-protected crystals, and usually no ice rings were observed for smaller crystals (< 0.3 mm). These results show that flash-cooling-induced damage to protein crystals can be eliminated by decreasing the crystal size to increase cooling rates and decrease internal temperature gradients [1] or by more closely matching the thermal expansion coefficient of crystal solvent to that of protein lattice [2].

[1] "Heat Transfer from Protein Crystals: Implications for Flash Cooling and X-ray Beam Heating," S. Kriminski, M. Kazmierczak and R.E. Thorne, accepted to Acta Cryst. D.

[2] "Flash Cooling and Annealing of Protein Crystals," S. Kriminski, C.L. Caylor, M.C. Nonato, K.D. Finkelstein and R.E. Thorne, Acta Cryst. D58, 459-471, (2002).