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Cyanogen‐induced γ‐glutamyl to imidazole cross‐link in carbonic anhydrase
Author(s) -
Kirley Jane W.,
Day Richard A.,
Kreishman George P.
Publication year - 1985
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(85)80139-3
Subject(s) - imidazole , carbonic anhydrase , cyanogen bromide , chemistry , biochemistry , stereochemistry , enzyme , peptide sequence , gene
The irreversible inhibition of carbonic anhydrase by cyanogen occurs by a unique mechanism. Cyanogen is an affinity label: it behaves like a carbodiimide and produces an intra‐molecular cross‐link without being incorporated. The nucleophile‐labile cross‐link is formed between a γ‐COOH of a Glu and an imidazole of a His with a 1:1:1 stoichiometry with the enzyme. The deletion of ~ 1 Glu and ~ 1 His was noted by amino acid analysis of enzymatically hydrolyzed carbonic anhydrase. The modified Glu was converted to 2,4‐diaminobutanoic acid and quantitated by amino acid analysis. The presence and quantity of modified His was supported through high‐resolution proton NMR analysis.