PHOSPHORYLATING ENZYMES INVOLVED IN GLUCOSE FERMENTATION OF ACTINOMYCES-NAESLUNDII

Enzymatic activities involved in glucose fermentation of Actinomyces n aeslundii were studied with glucose-grown cells from batch cultures, G lucose could be phosphorylated to glucose 6-phosphate by a glucokinase that utilized polyphosphate and GTP instead of ATP as a phosphoryl do nor. Glucose 6-phosphate was further metabolized to the end products l actate, formate, acetate, and succinate through the Embden-Meyerhof-Pa rnas pathway. The phosphoryl donor for phosphofructokinase was only PP i. Phosphoglycerate kinase, pyruvate kinase, and acetate kinase couple d GDP as well as ADP, but P-i compounds were not their phosphoryl acce ptor, Cell extracts showed GDP-dependent activity of phosphoenolpyruva te carboxykinase, which assimilates bicarbonate and phosphoenolpyruvat e into oxaloacetate, a precursor of succinate, Considerable amounts of GTP, polyphosphate, and PPi were found in glucose-fermenting cells, i ndicating that these compounds may serve as phosphoryl donors or accep tors in Actinomyces cells. PPi could be generated from UTP and glucose 1-phosphate through catalysis of UDP-glucose synthase, which provides UDP-glucose, a precursor of glycogen.