HETEROGENEITY OF BOVINE CARBOXYPEPTIDASE AI CHROMATOGRAPHIC PURIFICATION OF CARBOXYPEPTIDASE A (ANSON)

Bovine carboxypeptidase A (Anson) has been shown to contain at least five components when chromatographed on DEAE-cellulose (DE-52) in the presence of the competitive inhibitor β-phenylpropionate. All five fractions have the same specific activity toward peptide and ester substrates. Partial sequence determination of the amino- and carboxyl-terminal fragments obtained by cleavage with cyanogen bromide of fractions I, II, III, IV, and V reveal that they are carboxypeptidase Aα, carboxypeptidase AValβ, carboxypeptidaseALeuα, carboxypeptidase AValγ, and carboxypeptidase ALeuγ, respectively. All five species differ in their rates of heat inactivation at 50° indicating that both chain length and the amino acid replacement may affect the conformational stability of the molecule as a whole. An additional amino acid replacement genetically linked with the valine-leucine replacement is proposed. © 1969, American Chemical Society. All rights reserved.