title: Structural properties of human carbonic anhydrase II at pH 9.5.
abstract: The structure of human carbonic anhydrase II at pH 9.5 has been studied by X-ray crystallographic methods to 2.2 A resolution. These studies complement those performed under acidic conditions in which the catalytically-important proton-shuttle group, His-64, exhibits conformational mobility about side-chain torsion angle chi 1. However, no structural changes are observed in the conformation of His-64 at high pH. Therefore, we conclude that the protonation of His-64 (as well as zinc-bound hydroxide) may be a factor which contributes to the predominantly "out" conformation for His-64 observed at low pH.
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia 19104-6323.
authors.forename: S K
authors.initials: SK
authors.lastname: Nair
authors.forename: D W
authors.initials: DW
authors.lastname: Christianson
mesh_terms: D002256:Carbonic Anhydrases / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D011487:Protein Conformation; D014961:X-Ray Diffraction
chemical_list: D002256:Carbonic Anhydrases