title: Structure of bovine carbonic anhydrase II at 1.95 A resolution.
abstract: Carbonic anhydrase (CA) is a zinc-containing enzyme that catalyzes the reversible hydration of CO2 to HCO3-. In eukaryotes, the enzyme plays a role in various physiological functions, including interconversion between CO2 and HCO3- in intermediary metabolism, facilitated diffusion of CO2, pH homeostasis and ion transport. The structure of bovine carbonic anhydrase II (BCA II) has been determined by molecular replacement and refined to 1.95 A resolution by simulated-annealing and individual B-factor refinement. The final R factor for the BCA II structure was 19.4%. BCA II has a C-terminal knot structure similar to that observed in human CA II. It contains one zinc ion in the active site coordinated to three histidines and one putative water molecule in a tetrahedral geometry. The structure of BCA II reveals a probable alternative proton-wire pathway that differs from that of HCA II.
authors.affiliation: Department of Life Science, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Japan.
authors.forename: Ryuta
authors.initials: R
authors.lastname: Saito
authors.forename: Takao
authors.initials: T
authors.lastname: Sato
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ikai
authors.forename: Nobuo
authors.initials: N
authors.lastname: Tanaka
mesh_terms: D000818:Animals; D001665:Binding Sites; D024402:Carbonic Anhydrase II / Q000737:chemistry*; D002417:Cattle; D003460:Crystallization; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008958:Models, Molecular; D015394:Molecular Structure; D011487:Protein Conformation; D015032:Zinc
chemical_list: D024402:Carbonic Anhydrase II; D015032:Zinc