[Methylpyrophosphate, the simplext organic substrate of yeast inorganic phyrophosphatase]

The interaction between yeast inorganic pyrophosphatase and the simplest organic substrate, methylpyrophosphate, was studied. Methylpyrophosphate hydrolysis occurred most intensively in the presence of Zn2+ less intensively in the presence of CO2+ and Mn2+ and did not occur at all in the presence of Mg2+. The complex convertible into reaction products contains two Zn2+ and one molecule of zinc methylpyrophosphate per one active center. The activator metal ions are linked with pyrophosphatase consecutively; each of the two enzyme forms produced can bind to the substrate. The values of the maximal velocity and the constants of the substrate binding to the pyrophosphatase were calculated.