Activation of glucose-6-phosphate dehydrogenase of enzyme-deficient subjects. II. Properties of the activator and the activation reaction.

The primary metabolic defect in subjects susceptible to hemolysis by various drugs and fava beans is considered to be the low glucose-6-phosphate dehydrogenase (G6PD) activity in their red cells (1, 2). Such diminished enzymatic activity could be the end result of qualitative or quantitative changes in the enzyme as well as enzyme inhibition or lack of enzyme activation. However, studies on the properties of erythrocyte G6PD in such subjects and in normal subjects revealed no qualitative difference between them (3, 4). In a previous communication we demonstrated the presence of an activator of G6PD in normal erythrocyte stroma which increased the G6PD activity in the "sensitive" 1 hemolysate (5). This activator was found to be absent in the stroma of "sensitive" erythrocytes. Our recent finding that G6PD activity is also present in red cell stroma made it necessary to reinvestigate the validity of the G6PD activator.