Regulation of Glucose 6-Phosphate Dehydrogenase in Blue-Green Algae

Abstract

Glucose 6-phosphate dehydrogenase (EC 1. 1.1. 49) has been partially purified from Anacystis nidulans and Anabaena flos-aquae by means of anmnonium sulfate fractionation and exclusion gel chromatography and the kinetic properties determined. Glucose 6-phosphate dehydrogenase from these blue-green algae exhibits Michaelis-Menten kinetics at pH 6.7. At this pH, Km values of 0.37 mM for glucose 6-phosphate and 10 zM for NADP were determined. At a pH above 7.4, the enzyme exhibits sigmoidal kinetics with respect to glucose 6-phosphate saturation but the saturation curve for NADP remains hyper-bolic.