title: X-ray studies on cross-linked lysozyme crystals in acetonitrile-water mixture.
abstract: Tetragonal crystals of hen egg white lysozyme were cross-linked and subjected to X-ray diffraction study in acetonitrile-water media with different acetonitrile concentrations. Crystals in neat acetonitrile did not scatter X-ray well. Structures of crystals in neat water, in 90% and 95% acetonitrile, and crystal back-soaked from acetonitrile to water, were determined to about 2 A resolution. For crystals in both 90% acetonitrile, and crystal back-soaked from acetonitrile to water, were determined to about 2 A resolution. For crystals in both 90% and 95% acetonitrile, only one protein-bond acetonitrile molecule is found in the active site cleft, and its location and binding-protein mode is similar to the C subunit of polysaccharide. The alteration in conformation and hydrogen-bond pattern involving water as solvent causes the reduction of the protein's flexibility in organic media. The back-soaked crystal regained its ordinary three-dimensional structure in water.
authors.affiliation: Department of Chemistry, Peking University, Beijing, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.forename: G
authors.initials: G
authors.lastname: Zhu
authors.forename: Q
authors.initials: Q
authors.lastname: Huang
authors.forename: M
authors.initials: M
authors.lastname: Qian
authors.forename: M
authors.initials: M
authors.lastname: Shao
authors.forename: Y
authors.initials: Y
authors.lastname: Jia
authors.forename: Y
authors.initials: Y
authors.lastname: Tang
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D003432:Cross-Linking Reagents; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009113:Muramidase / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D000097:Acetonitriles; D003432:Cross-Linking Reagents; D009113:Muramidase; C032159:acetonitrile