An inorganic pyrophosphatase of swine brain.

In recent years, a number of reactions leading to the liberation of inorganic pyrophosphate have been described. Since the only known reaction leading to a net decrease in the concentration of inorganic pyrophosphate is that of hydrolysis, the properties of inorganic pyrophosphatases are of interest. The discovery of an inorganic pyrophosphatase in muscle was made by Lohmann (2) and one was demonstrated in mammalian nervous tissue by Gordon (3). A purification procedure for an inorganic pyrophosphatase of nervous tissue has been reported (4). This procedure resulted in a preparation hydrolyzing adenosine triphosphate as well as inorganic pyrophosphate. The characterization of the inorganic pyrophosphatases of mammalian nervous tissue (as well as of other tissues) has been complicated by heterogeneity of the preparations used. The dependence of activity upon sulfhydryl groupings, the effect of metal ions, and the relationship of adenosinetriphosphatase and inorganic pyrophosphatase have been disputed. The enzyme described here is conveniently prepared and appears to be quite stable.