Determination of carboxypeptidase A using N-acetyl-phenylalanyl-3-thiaphenylalanine as substrate: application to a direct serum assay.
N-Acetyl-L-phenylalanyl-L-3-thiaphenylalanine has been shown to be a substrate for carboxypeptidase A. Hydrolysis of the compound obeys Michaelis-Menten kinetics with a KM of 0.22 mM and a kcat of 6720 min-1 at 22 degrees C. A colorimetric assay, employing Ellman's reagent to detect the thiophenol released upon cleavage of the peptide, has been developed. The assay can be used for the direct determination of carboxypeptidase A in serum.
D000818:Animals; D002268:Carboxypeptidases / Q000032:analysis* / Q000097:blood; D043422:Carboxypeptidases A; D002417:Cattle; D003124:Colorimetry / Q000379:methods*; D004151:Dipeptides; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D010195:Pancreatitis / Q000175:diagnosis / Q000201:enzymology; D013379:Substrate Specificity
D004151:Dipeptides; C052190:N-acetylphenylalanyl-3-thiaphenylalanine; D002268:Carboxypeptidases; D043422:Carboxypeptidases A