THE ENZYMATIC CONVERSION OF GLTJCOSE-l-PHOS- PHORIC ESTER TO 6-ESTER IN TISSUE EXTRACTS*

The formation of glucose-l-phosphoric acid (l-ester) and its conversion to glucose-6-phosphoric acid have been shown to be initial steps in the degradation of glycogen to lactic acid (1). The enzyme which brings about the conversion of the l-ester has been found in extracts of rabbit muscle, brain, heart, liver, in dog and frog muscle extracts, and in extracts of yeast (2); it is presumably present in all cells which ferment glycogen. The present report deals with a study of the enzyme which causes a migration of the phosphate group from carbon atom 1 to the spatially adjacent carbon atom 6; the enzyme will be referred to as phosphoglucomutase.’ Owing to the presence, in all extracts, of the extremely active equilibrium enzyme2 of Lohmann (5), part of the glucose-6-phosphate is converted almost instantaneously to fructose-6-phosphate. The equilibrium mixture formed is referred to as 6-ester. Phosphoglyceromutase catalyzes a reversible equilibrium reaction, while as yet no indication has been found for a reversibility of the reaction catalyzed by phosphoglucomutase.