title: Identification of human placental leucine aminopeptidase as oxytocinase.
abstract: Human placental leucine aminopeptidase (P-LAP) was purified from retroplacental serum for the first time by serial chromatography on columns of Matrex Blue A, DEAE-Sepharose CL-6B, phenyl-Sepharose 4B, chelating-Sepharose, and Sepharose CL-6B. The purified P-LAP was apparently homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the apparent molecular weight (Mr) was estimated to be 210,000. By comparing P-LAP activity with cystine aminopeptidase activity, we concluded that both activities were shared by the same molecule. We also examined the hydrolytic activity of P-LAP using naturally occurring peptide hormones and found that the enzyme hydrolyzed oxytocin, vasopressin, and angiotensin III. These results suggest that P-LAP shows oxytocinase activity and plays an important role in the regulation of the plasma level of these hormones during pregnancy.
authors.affiliation: Suntory Institute for Biomedical Research, Osaka, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Tsujimoto
authors.forename: S
authors.initials: S
authors.lastname: Mizutani
authors.forename: H
authors.initials: H
authors.lastname: Adachi
authors.forename: M
authors.initials: M
authors.lastname: Kimura
authors.forename: H
authors.initials: H
authors.lastname: Nakazato
authors.forename: Y
authors.initials: Y
authors.lastname: Tomoda
mesh_terms: D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D010122:Cystinyl Aminopeptidase / Q000097:blood* / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005312:Fetal Blood; D006801:Humans; D007700:Kinetics; D007931:Leucyl Aminopeptidase / Q000097:blood* / Q000302:isolation & purification; D008970:Molecular Weight; D010920:Placenta; D011247:Pregnancy; D013379:Substrate Specificity
chemical_list: D007931:Leucyl Aminopeptidase; D010122:Cystinyl Aminopeptidase