1cah
From Proteopedia
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STRUCTURE OF COBALT CARBONIC ANHYDRASE COMPLEXED WITH BICARBONATE
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Overview
The three-dimensional structure of a complex between catalytically active cobalt(II) substituted human carbonic anhydrase II and its substrate bicarbonate was determined by X-ray crystallography (1.9 A). One water molecule and two bicarbonate oxygen atoms are found at distances between 2.3 and 2.5 A from the cobalt ion in addition to the three histidyl ligands contributed by the peptide chain. The tetrahedral geometry around the metal ion in the native enzyme with a single water molecule 2.0 A from the metal is therefore lost. The geometry is difficult to classify but might best be described as distorted octahedral. The structure is suggested to represent a water-bicarbonate exchange state relevant also for native carbonic anhydrase, where the two unprotonized oxygen atoms of the substrate are bound in a carboxylate binding site and the hydroxyl group is free to move closer to the metal thereby replacing the metal-bound water molecule. A reaction mechanism based on crystallographically determined enzyme-ligand complexes is represented.
Disease
Known disease associated with this structure: Osteopetrosis, autosomal recessive 3, with renal tubular acidosis OMIM:[611492]
About this Structure
1CAH is a Single protein structure of sequence from Homo sapiens with and as ligands. Active as Carbonate dehydratase, with EC number 4.2.1.1 Full crystallographic information is available from OCA.
Reference
Structure of cobalt carbonic anhydrase complexed with bicarbonate., Hakansson K, Wehnert A, J Mol Biol. 1992 Dec 20;228(4):1212-8. PMID:1474587
Page seeded by OCA on Thu Feb 21 12:04:05 2008
