Human mast cell carboxypeptidase. Purification and characterization.
A carboxypeptidase activity was recently identified in highly purified human lung mast cells and dispersed mast cells from skin. Using affinity chromatography with potato-tuber carboxypeptidase inhibitor as ligand, mast cell carboxypeptidase was purified to homogeneity from whole skin extracts. The purified enzyme yielded a single staining band of approximately 34,500 D on SDS-PAGE. Carboxypeptidase enzyme content estimated by determination of specific activity, was 0.5, 5, and 16 micrograms/10(6) mast cells from neonatal foreskin, adult facial skin, and adult foreskin, respectively. Human mast cell carboxypeptidase resembled bovine carboxypeptidase A with respect to hydrolysis of synthetic dipeptides and angiotensin I, but was distinguished from carboxypeptidase A in its inability to hydrolyze des-Arg9 bradykinin. The amino acid composition of human mast cell carboxypeptidase was similar to the composition of rat mast cell carboxypeptidase. The amino-terminal amino acid sequence of mast cell carboxypeptidase demonstrated 65% positional identity with human pancreatic carboxypeptidase B, but only 19% with human carboxypeptidase A. Thus, human mast cell carboxypeptidase is a novel member of the protein family of zinc-containing carboxypeptidases, in that it is functionally similar but not identical to bovine carboxypeptidase A, but has structural similarity to bovine and human pancreatic carboxypeptidase B.
Goldstein
S M
SM
Department of Dermatology, University of California, San Francisco 94143.
Kaempfer
C E
CE
Kealey
J T
JT
Wintroub
B U
BU
D000328:Adult; D000595:Amino Acid Sequence; D043424:Carboxypeptidase B; D002268:Carboxypeptidases / Q000302:isolation & purification* / Q000502:physiology; D043422:Carboxypeptidases A; D006801:Humans; D007231:Infant, Newborn; D008407:Mast Cells / Q000201:enzymology*; D008969:Molecular Sequence Data; D012867:Skin / Q000201:enzymology
D002268:Carboxypeptidases; D043422:Carboxypeptidases A; D043424:Carboxypeptidase B