Purification and properties of human placental aminopeptidase B.
Aminopeptidase B (EC 3.4.11.6; L-arginyl-beta-naphthylamidase) was purified 1,800-fold from human placental cytoplasm and characterized. The enzyme was subjected to ammonium sulfate fractionation and a series of chromatographies on DE-52, hydroxylapatite, Bio-gel A 0.5 m and L-arginine-Sepharose. The native molecular mass of the enzyme was estimated to be 220,000 by gel filtration. The molecular mass was estimated to be about 83,000 by SDS/PAGE in the absence of 2-mercaptoethanol, suggesting that the enzyme exists in a polymeric form. The isoelectric point of the enzyme was 5.4. The purified enzyme was most active at pH 7.2 with L-arginyl-beta-naphthylamide as substrate and the Km value for this enzyme was 0.3 mmol/l. Human placental aminopeptidase B was markedly activity by Cl-. Bestatin and arphamenin, low molecular weight peptides, showed appreciable inhibition of this enzyme. However, amastatin and puromycin did not inhibit the enzyme. Bacitracin markedly activated this enzyme.
Nagata
Y
Y
Department of Obstetrics and Gynecology, Nagoya University School of Medicine, Japan.
Mizutani
S
S
Nomura
S
S
Kurauchi
O
O
Kasugai
M
M
Tomoda
Y
Y
D000626:Aminopeptidases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007526:Isoelectric Point; D008970:Molecular Weight; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D013329:Structure-Activity Relationship
D000626:Aminopeptidases; C019721:aminopeptidase B