Biosynthesis of bacterial glycogen: V. The activation and inhibition of the adenosine diphosphate glucose pyrophosphorylase of Arthrobacter viscosus NRRL B1973

Abstract

Adenosine diphosphate-glucose pyrophosphorylase from Arthrobacter viscosus NRRL B1973 was found to be activated by fructose-6-P, pyruvate, deoxyribose-5-P and ribose-5-P. Fructose-6-P was the most effective activator. Fructose-6-P increased the V max of pyrophosphorolysis of ADP-glucose 2.5-fold, and the V max of synthesis of ADP-glucose from ATP and glucose-1-P, 7-fold. The apparent K m 's for ATP, pyrophosphate, and ADP-glucose were decreased in the presence of fructose-6-P. Pyruvate increased the V max of pyrophosphorolysis 2-fold and of synthesis 6-fold. However, pyruvate only decreased the K m for pyrophosphate. The K m for glucose-1-P was not effected by either pyruvate or fructose-6-P. The enzyme was found to be inhibited by phosphate, sulfate, AMP, ADP, phosphoenolpyruvate, GMP, and GDP. However, fructose-6-P completely overcame (reversed) these inhibitions. The relationship of these findings to the control of bacterial glycogen synthesis is discussed.