[Microsomal glucose 6-phosphate dehydrogenase in the rat testis--an testis--specific isoenzyme?].

Mammalian tissues contain cytosolic and microsomal glucose 6-phosphate dehydrogenase (G6PD). In the present study it was examined whether the microsomal G6PD in liver and testis of the rat are homologous. Kinetic parameters and immunological reactivity were estimated using rabbit antiserum against mice erythrocyte G6PD. Kinetic parameters allow to distinguish cytosolic and microsomal G6PD in rat liver but not in testis, whereas the immunological properties of the testis enzymes are different. The cytosolic G6PDs from liver and testis of the rat are identical enzymes having extremely similar properties to mice erythrocyte G6PD. The microsomal G6PD of both organs are not homologous enzymes. Testicular microsomal G6PD is likely to be an organ specific G6PD-isoenzyme.