Purification and properties of a carboxypeptidase inhibitor from potatoes

• Published in: The Journal of biological chemistry Vol. 249; no. 17; pp. 5495 - 5499
• Main Authors: Ryan, C.A, Hass, G.M, Kuhn, R.W
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 10.09.1974
• Subjects: Amino Acid Sequence; Amino Acids - analysis; Animals; Carboxypeptidases - antagonists & inhibitors; Cattle; Chromatography, Gel; Chromatography, Ion Exchange; Decapoda - enzymology; Disulfides - analysis; Electrophoresis, Disc; Enzyme Inhibitors - isolation & purification; horticultural crops; Kinetics; Mercaptoethanol; Molecular Weight; Oxidation-Reduction; Peptides - isolation & purification; plant biochemistry; plant physiology; Plants; Protein Conformation; Species Specificity; Sulfhydryl Compounds - analysis; Swine
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(20)79755-3

An inhibitor of the pancreatic carboxypeptidase A and B (R yan , C. A. (1971) Biochem. Biophys. Res. Commun. 44, 1265–1270) has been purified from Russet Burbank potatoes. The inhibitor is a polypeptide having a molecular weight of approximately 3100, as estimated by gel filtration, and contains 37 to 39 amino acid residues. The amino group of the NH 2 -terminal residue is blocked and the COOH-terminal residue is apparently glycine. The presence of 6 halfcystine residues per molecule and absence of free thiols indicate that the inhibitor possesses three disulfide bonds. The K i values for the inhibition of the peptidase activities of bovine carboxypeptidase A and porcine carboxypeptidase B were estimated to be 5 x 10 -9 m and 5 x 10 -8 m , respectively.