Abstract
The rat glucose 6-phosphate dehydrogenase isozymes of cell sap origin designated D, F1, F2 and F3 were found to be interconvertible with each other in the presence or absence of mercaptans. The D and F3 enzymes were the oxidized, the F1 was the reduced and the F2 was the intermediate form. Molecular weight estimation by the polyacrylamide gel electrophoresis and Sephadex G-200 methods demonstrated that the D enzyme had twice the molecular weight of the F enzymes. The mitochondrial enzyme which moved as fast as the F3 enzyme of cell sap origin was not modified with mercaptans. Together with previous data, the present results caution in the interpretation of zymograms.