The active site of carboxypeptidase CU. I. Evidence for serine in the active sites of carboxypeptidases CUa and CUb.

Abstract

Carboxypeptidases CUa and CUb were both inactivated with incorporation of 1 mol 32P-labeled diisopropyl fluorophosphate per mol enzyme. The amino acid residue that reacted with this reagent was a serine residue in the active site of each enzyme. The amino acid sequence around this reactive serine residue was determined to be Glu-Gly-Asp-Ser-Gly-Gly-Glu-Leu for both enzymes by sequence analysis of three radioactive peptides isolated from partial acid hydrolysates of the 32P-labeled enzymes.