Preparation of 32P-labeled inositides and their degradation by soluble kidney enzymes.

A method is described for the preparation of radioactive inositol lipids for studies of their enzymic degradation. Kidney cytosol fractions have been used to produce diesteratic cleavage. High voltage electrophoresis at pH 4.3 is used to separate D-myoinositol 1 : 2-cyclic phosphate and D-myoinositol 1-phosphate from hydrolysis of phosphatidylinositol. Radioactivity co-migrating with myoinositol diphosphate and triphosphate is separated by electrophoresis at pH 1.5 following enzymatic hydrolysis of phosphatidylinositol phosphate and phosphatidylinositol diphosphate. Relative activities for hydrolysis of the various inositides suggest the presence of more than one phosphodiesterase.