HEAVY CROSS-LINKED PROTEIN CRYSTALS AND ITS APPLICATION. Qichen Huang, Minxie Qian, Zhimin Wang and Youqi Tang, Department of Chemistry, Peking University, Beijing 100871, P.R.China

Crystals of lysozyme, concanavalin A, and trichosanthin, were heavy cross-linked at gluaraldahyde (up to 10.0%, 50 days), the crystals become very stable even subsequently solvent substitution by denaturant, organic solvent, non- aqueous solution contain some organic probe compouds (which are insoluble in water), water, and back soaking of water or mother liquor, respectively. Although their some cell dimensions have much changed (up to 7%), they keep original space group and still diffract X-ray to high resolution and can be used to crystallographic studies for differenet special purposes, for example, to determin the partially defolding structures, to understand the behavior the structural water on the protein bound, to find the binding sites of antibody or drugs. This method may also be used to search heavy atom derivatives, to study time-resolved structures of protein reaction dynamics. Some selected crystals data collection conditions are listed as follows. LYS-I (lysozyme, in 2.0M guanidine hydrochloride solution) has collected data to 2.1 A resolution, LYS-II (in 3.0M guanidine hydrochloride), 2.2Å, LYS-III(in 90% v/v aceto- nitril and water), 1.9 Å, LYS-IV(in 95% acetonitril), 1.9 Å, LYS-V(in anhydrous acetonitrile), 2.5 Å, LYS-VI (in pure water), 1.9 Å, and LYS-VII (back soaking from aceto- nitrile to water) 2.0Å, for comparing. CON-I(concanavalin Å in anhydrous acetonitrile), 2.5 Å, CON-II(in water), 1.9 Å, CON-III (back soaking from acetonitrile to water), 1.9 Å, CON-IV (in mother liquor), 1.8 Å for comparing. TCS-I (trichosanthin, in anhydrous acetonitrile), 2.3 Å, TCS-II (in acetonitrile solution contain organic fluorine compoud as probe for serching the bind sites of antibody), 2.5 Å, TCS-III (in mother liquor) 1.9 Å, for comparing. Some data set refinements had been carried. In CON-I, the big change (more than 14Å) of C-terminer four residues peptide chain, and the direction reversing of one loop are observed. Now, further refinements of all other data set are in progress.