Vascular, post proline cleaving enzyme: metabolism of vasoactive peptides.

摘要: Vasoactive peptides contain a high proportion of proline residues which make them resistant to hydrolysis by many peptidases. However, post cleaving enzyme (PPCE; EC 3.4.21.26), specific endopeptidase specifically hydrolyzes internal peptide bonds on the carboxyl side residues, has been shown inactivate numerous vasoactive including angiotensins, kinins, substance P, vasopressin and oxytocin. In order determine whether PPCE could be involved in vascular metabolism peptides, we carried out localization characterization studies PPCE-like activity hog aorta mesenteric artery. was assayed fluorometrically at pH 7.0 using substrate CBZ-Gly-Pro-4-methyl-coumarinylamide. The subcellular distribution essentially same as that cytosolic marker lactic dehydrogenase (LDH). enriched six-fold fraction (11.4 +/- 2.7 units/mg) unlike plasma membrane-bound exopeptidase dipeptidyl-(amino)peptidase IV (DAP IV; 3.4.14.5), little or no detected microsomal membrane fractions. Similar characterized from other sites, stabilized activated dithiothreitol EDTA, inhibited DFP, p-chloromercuriphenyl sulfonic acid, L-1-tosylamido-2-phenylethylchloromethyl ketone, Cu++, Ca++, Zn++. Vascular unaffected inhibitors trypsin kallikrein (Aprotinin, ABTI), aminopeptidase M (bestatin, amastatin), neutral (phosphoramidon), angiotensin I converting (captopril) carboxypeptidase N (MERGETPA). These data demonstrate is present endothelium and/or smooth muscle.(ABSTRACT TRUNCATED AT 250 WORDS)