Yeast Inorganic Pyrophosphatase

摘要: The kinetics of the Mg2+ activation crystalline yeast inorganic pyrophosphatase have been thoroughly investigated from pH 7.40 to 9.05 using a sensitive isotope assay in order determine role divalent metal ion activator reaction. A computer program has devised for calculating concentration each various components complex equilibrium involving and pyrophosphate (PPi). reaction rate was measured over wide range PPi concentrations, dependence kinetically analyzed by computerized algorithm nonlinear regression. analysis included testing several plausible kinetic models goodness fit data, determination best values parameters models. simplest model which provides good all data involves binding free enzyme followed ligands. Both MgPPi Mg2PPi are substrates; at latter is hydrolyzed 22% as rapidly former. Free bound but not significant rate. On basis these studies we propose two roles this reaction: form binds substrate, formation substrate complexing with PPi. These entirely consistent our previously reported enzyme.