Demonstration of a novel type of ATP-diphosphohydrolase (EC 3.6.1.5) in the bovine lung.

摘要: Abstract A novel type of ATP-diphosphohydrolase (ATPDase) is demonstrated in bovine lung. The enzyme has an optimum pH 7.5 and catalyzes the hydrolysis beta- gamma-phosphate residues from diphospho- triphosphonucleosides. It requires Ca2+ or Mg2+ insensitive to ouabain, inhibitor Na+/K(+)-ATPase, P1,P5-di(adenosine 5')-pentaphosphate, adenylate kinase, tetramisole, alkaline phosphatase. In contrast, sodium azide (10 mM), a known ATPDases mitochondrial ATPases, as well mercuric chloride microM) gossypol (2,2'-bis[8-formyl-1,6,7-trihydroxy-5-isopropyl-3-methylnaphthalene]) (35 are powerful inhibitors this enzyme. same inhibition profile obtained with ATP ADP substrate, thereby supporting concept common catalytic site for these substrates. This further confirmed by localization after polyacrylamide gel electrophoresis under nondenaturing conditions kinetic properties, namely dependence profiles, heat inactivation, 60Co irradiation-inactivation curves. native molecular mass calculated gamma-irradiation-inactivation curves estimated at 70 +/- 3 kDa, whereas Km,app Vmax,app ATPDase evaluated 7 2 microM 1.1 0.3 mumol Pi/min/mg protein, respectively. comparison properties those pig pancreas (Type I) aorta II) lead us believe that hitherto undescribed ATPDase. By reference previously described ATPDase, we propose identify Type III (EC 3.6.1.5).