Kinetic properties of placental aminopeptidase A: N-terminal degradation of angiotensin II.
Purified placental aminopeptidase A cleaved N-terminal aspartic acid of Angiotensin II, and it was inhibited by amastatin. Amastatin and various angiotensin analogs having N-terminal dicarboxylic acid were potent inhibitors of the enzyme. Kinetic analysis indicated that amastatin, angiotensin II, the N-terminal tripeptide of angiotensin II, and aspartic acid were competitive inhibitors, with Ki values 1.25 X 10(-7) M, 2.40 X 10(-5) M, 2.67 X 10(-4) M, and 1.2 X 10(-3)M respectively. The enzyme was also inhibited by transition metals, such as Zn2+, Cu2+, Cd2+ and Ni2+. Serum aminopeptidase A activity progressively increased during the course of normal pregnancy.
D000596:Amino Acids / Q000494:pharmacology; D000626:Aminopeptidases / Q000037:antagonists & inhibitors / Q000097:blood / Q000378:metabolism*; D000804:Angiotensin II / Q000378:metabolism*; D000900:Anti-Bacterial Agents; D001224:Aspartic Acid / Q000378:metabolism; D002413:Cations, Divalent; D005260:Female; D043384:Glutamyl Aminopeptidase; D006801:Humans; D007700:Kinetics; D009842:Oligopeptides / Q000494:pharmacology; D010455:Peptides; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy
D000596:Amino Acids; D000900:Anti-Bacterial Agents; D002413:Cations, Divalent; D009842:Oligopeptides; D010455:Peptides; D000804:Angiotensin II; D001224:Aspartic Acid; C016977:amastatin; D000626:Aminopeptidases; D043384:Glutamyl Aminopeptidase