An improved assay of inorganic phosphate in the presence of extralabile phosphate compounds: Application to the ATPase assay in the presence of phosphocreatine

Abstract

Two methods of determining inorganic phosphate in the presence of labile phosphate compounds using the catalyst polyvinylpyrrolidone (PVP) are described. The first method provides a simple assay of ATPase activity at room temperature without deproteinization. The second method minimizes the decomposition of phosphocreatine during the assay to 1%. An application to the measurement of myofibrillar ATPase in the presence of phosphocreatine is given, as well as the advantages of the methods.