Acta Crystallographica Section D

Biological Crystallography

Volume 57, Part 7 (July 2001)

research papers

Acta Cryst. (2001). D57, 929-940 [ doi:10.1107/S0907444901004504 ]

Structural effects of monovalent anions on polymorphic lysozyme crystals

M. C. Vaney, I. Broutin, P. Retailleau, A. Douangamath, S. Lafont, C. Hamiaux, T. Prangé, A. Ducruix and M. Riès-Kautt

Abstract: Understanding direct salt effects on protein crystal polymorphism is addressed by comparing different crystal forms (triclinic, monoclinic, tetragonal and orthorhombic) for hen, turkey, bob white quail and human lysozymes. Four new structures of hen egg-white lysozyme are reported: crystals grown in the presence of NapTS diffracted to 1.85 Å, of NaI to 1.6 Å, of NaNO₃ to 1.45 Å and of KSCN to 1.63 Å. These new structures are compared with previously published structures in order to draw a mapping of the surface of different lysozymes interacting with monovalent anions, such as nitrate, chloride, iodide, bromide and thiocyanate. An analysis of the structural sites of these anions in the various lysozyme structures is presented. This study shows common anion sites whatever the crystal form and the chemical nature of anions, while others seem specific to a given geometry and a particular charge environment induced by the crystal packing.

PDB references: 1b2k, 1hf4, 1lcn and 1b0d

Keywords: lysozyme; polymorphism; salt effects; anionic sites; crystallogenesis.