Enzymatic Synthesis of Glycerol l-Phosphate (D-a=Glycerophosphate)

“Microsomal” particulate fractions of rat organ homogenates are capable of catalyzing the synthesis of glycerol l-phosphate’ from inorganic pyrophosphate and glycerol. The product has been isolated and characterized by elementary analysis, specific rotation, and chemical and enzymatic studies. PPi-glycerol phosphotransferase is presumably specific for the primary carbinol group of glycerol opposite to that which is phosphorylated by ATP-glycerol phosphotransferase (glycerol kinase). The distribution and some of the kinetic properties of PPi-glycerol phosphotransferase have been studied and compared with those of PPi-glucose phosphotransferase, which catalyzes the synthesis of glucose 6-phosphate. The two activities are roughly parallel in liver, kidney, and intestinal mucosa, and glucose is a competitive inhibitor of the synthesis of glycerol l-phosphate by these organ preparations. Spleen, brain, and lung preparations catalyze the phosphorylation of glycerol from PPi while they are completely incapable of glucose 6-phosphate synthesis. In these organs glucose does not inhibit the synthesis of glycerol l-phosphate. This suggests that there are at least two transferase enzymes which phosphorylate glycerol, one of which may be the same as the liver PPi-glucose phospho-