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Metal poison inhibition of carbonic anhydrase
Author(s) -
Lindahl Martin,
Svensson L. Anders,
Liljas Anders
Publication year - 1993
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.340150207
Subject(s) - carbonic anhydrase , chemistry , cyanate , zinc , cyanide , molecule , metal , hydrogen bond , crystal structure , inorganic chemistry , enzyme , peptide , carbonic anhydrase ii , metal ions in aqueous solution , stereochemistry , crystallography , biochemistry , polymer chemistry , organic chemistry
Carbonic anhydrase is inhibited by the “metal poison” cyanide. Several spectroscopic investigations of carbonic anhydrase where the natural zinc ion has been replaced by cobalt have further strengthened the view that cyanide and cyanate bind directly to the metal. We have determined the structure of human carbonic anhydrase II inhibited by cyanide and cyanate, respectively, by X‐ray crystallography. It is shown that the inhibitors replace a molecule of water, which forms a hydrogen bond to the peptide nitrogen of Thr‐199 in the native structure. The coordination of the zinc ion is hereby left unaltered compared to the native crystal structure, so that the zinc coordinates three histidines and one molecule of water or hydroxyl ion in a tetrahedral fashion. The binding site of the two inhibitors is identical to what earlier has been suggested to be the position of the substrate (CO 2 ) when attacked by the zinc bound hydroxyl ion. The peptide chain undergoes no significant alterations upon binding of either inhibitor. © 1993 Wiley‐Liss, Inc.