Characterization of a secretase activity which releases angiotensin-converting enzyme from the membrane.

摘要: Angiotensin-converting enzyme (ACE; EC 3.4.1.15.1) exists in both membrane-bound and soluble forms. Phase separation Triton X-114 a competitive e.l.i.s.a. have been employed to characterize the activity which post-translationally converts amphipathic, form of ACE pig kidney microvilli into hydrophilic, form. This secretase was enriched similar extent as other microvillar membrane proteins, tightly membrane-associated, being resistant extensive washing membranes with 0.5 M NaCl, displayed pH optimum 8.4. The not affected by inhibitors serine-, thiol- or aspartic-proteases, nor reducing agents alpha 2-macroglobulin. metal chelators, EDTA 1,10-phenanthroline, inhibited activity, with, case EDTA, an inhibitor concentration 2.5 mM causing 50% inhibition. In contrast, EGTA maximum 15% at 10 mM. inhibition reactivated substantially (83%) Mg2+ ions, partially (34% 29%) Zn2+ Mn2+ ions respectively. EDTA-sensitive also present microsomal prepared from lung testis, human placenta, but absent intestinal brush-border membranes. released co-migrated on SDS/PAGE purified plasma, thus action location would be consistent it possibly having role post-translational proteolytic cleavage generate found blood, amniotic fluid, seminal plasma body fluids.