ACTIVATION OF GLUCOSE-6-PHOSPHATE DEHYDROGENASE OF ENZYME-DEFICIENT SUBJECTS. II. PROPERTIES OF THE ACTIVATOR AND THE ACTIVATION REACTION*

Abstract

A decreased activity of glucose-6-phosphate dehydrogenase (G-6-P. D.) was observed in the erythrocytes of Nergoes, Oriental Jews and Italians, susceptible to hemolysis, following the administration of primaquine, sulfanilamides and other drugs as well as fava beans. Those subjects will be referred to as "Sensitive". In the present investigation the effect of erythrocyte stroma on the enzyme activity was studied. This was carried out by pre-incubating a red cell hemolysate with stroma at 37[degree] for 1 hour. The enzymatic activity of G-6-P. D. was determined before and after the preincubation, by measuring the reduction of TPN. It was found that erythrocyte stroma of normal subjects is able to increase the enzymatic activity of "sensitive" haemolysates. Such an activation was not observed with stroma of "sensitive" subjects. The activation of the enzyme by the stromatic factor is temperature and pH dependent and progresses with time. The kinetic behavior of the activation effect and its temperature and pH dependence support the assumption that it is of an emzymatic nature.