Phosphorylation of Glucose in Kidney Extract

The reversible enzymatic equilibrium, glycogen + H3P04 ti glucose-l-phosphate, makes it likely that glucose, in order to be converted to glycogen, must first be phosphorylated.In looking for a system in which phosphorylation of glucose might be studied, our attention was directed to a series of papers by Kalckar (l-3).He found that addition of glucose, inorganic phosphate, and fluoride to a cell-free extract of kidney resulted in the formation of hexosediphosphate, a reaction which occurred under aerobic conditions only and was clearly connected with the oxygen uptake of the extract.Addition of substances (such as glutamic, citric, and succinic acids) which increased the respiration of the extracts also increased the phosphorylation of glucose.This aerobic mechanism of phosphorylation was also demonstrated in a few experiments with liver extract.In the experiments reported in the present paper an attempt was made to find the components of the phosphorylating system in kidney by reactivating extracts which had lost activity either by aging or by dialysis.In this manner it was found that at least two coenzymes, adenylic acid and cozymase, one specific ion, Mg++, and an oxidizable substrate (a dicarboxylic acid) are essential components of the system.EXPERIMENTAL Methods Active extracts could be prepared from beef, lamb, pig, cat, or rabbit kidney, obtained within 15 minutes after death of the