1z93

Human Carbonic Anhydrase III:Structural and Kinetic study of Catalysis and Proton Transfer.

spinqualitylabelsall models 1z93, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1z93 is a 1 chain structure with sequence from Human. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ZN Related: 1z97 Gene: CA3 (HUMAN) Activity: Carbonate dehydratase, with EC number 4.2.1.1 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [CAH3_HUMAN] Reversible hydration of carbon dioxide. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The residue phenylalanine 198 (Phe 198) is a prominent cause of the lower activity of human carbonic anhydrase III (HCA III) compared with HCA II and other isozymes which have leucine at this site. We report the crystal structures of HCA III and the site-directed mutant F198L HCA III, both at 2.1 A resolution, and the enhancement of catalytic activity by exogenous proton donors containing imidazole rings. Both enzymes had a hexahistidine extension at the carboxy-terminal end, used to aid in purification, that was ordered in the crystal structures bound in the active site cavity of an adjacent symmetry-related enzyme. This observation allowed us to comment on a number of possible binding sites for imidazole and derivatives as exogenous proton donors/acceptors in catalysis by HCA III. Kinetic and structural evidence indicates that the phenyl side chain of Phe 198 in HCA III, about 5 A from the zinc, is a steric constriction in the active site, may cause altered interactions at the zinc-bound solvent, and is a binding site for the activation of catalysis by histidylhistidine. This suggests that sites of activation of the proton-transfer pathway in carbonic anhydrase are closer to the zinc than considered in previous studies. Human carbonic anhydrase III: structural and kinetic study of catalysis and proton transfer.,Duda DM, Tu C, Fisher SZ, An H, Yoshioka C, Govindasamy L, Laipis PJ, Agbandje-McKenna M, Silverman DN, McKenna R Biochemistry. 2005 Aug 2;44(30):10046-53. PMID:16042381 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Carbonic anhydrase 3D structures

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