Carboxypeptidase A catalyses the release of the C-terminal amino acid from a polypeptide chain. The initial image shows carboxypeptidase with a dipeptide (green) in the active site.
The enzyme has . A zinc ion (violet) is present. The ion is involved in binding and catalysis.
Substrate binding involves three interactions between the substrate and the active site.
1. .
2. .
3. .
Catalysis involves .
(The substrate remained intact because Gly-Tyr is hydrolyzed very slowly and because X-ray crystallography was carried out at -9° C.)
