Characterization of the carboxypeptidase N secreted by Hep G2 cells.
Human hepatoma (Hep G2) cells secrete nanogram quantities of carboxypeptidase enzymes which are capable of hydrolyzing COOH-terminal lysine and arginine residues. A carboxypeptidase with a neutral pH optimum (greater than pH 7.0) was partially purified from the conditioned medium and compared with pure plasma carboxypeptidase N. The two enzymes behaved in a similar manner on gel filtration (apparent Mr = 280,000), DE52 ion exchange chromatography, and concanavalin A-affinity chromatography and were indistinguishable enzymatically and immunologically. Immunoblots of the Hep G2 and plasma carboxypeptidase N before and following deglycosylation with peptide-N4-[N-acetyl-beta-glucosaminyl]asparagine amidase F revealed a similar, if not identical, multimeric structure. A second carboxypeptidase with a lower molecular weight and a pH optimum of 5.0 was also detected in the Hep G2 medium.
Grimwood
B G
BG
Wadsworth Center for Laboratories and Research, New York State Department of Health, Albany 12201-0509.
Plummer
T H
TH
Tarentino
A L
AL
D000818:Animals; D015153:Blotting, Western; D002268:Carboxypeptidases / Q000378:metabolism*; D006528:Carcinoma, Hepatocellular / Q000201:enzymology*; D002460:Cell Line; D002846:Chromatography, Affinity; D006031:Glycosylation; D006801:Humans; D007700:Kinetics; D008113:Liver Neoplasms / Q000201:enzymology*; D001121:Lysine Carboxypeptidase / Q000302:isolation & purification / Q000378:metabolism*; D008970:Molecular Weight
D002268:Carboxypeptidases; D001121:Lysine Carboxypeptidase