Hi there,

NADPH is the molecule ensuring the reduction of oxidized glutathion into reduced glutathion. The latter is the main molecule of oxydative stress response. RBC are in charge to provide the NADPH necessary to oxydized glutathion reduction and G6PD is actually the only source of NADPH in RBC which makes the cell very dependent on the G6PD enzyme.

Other cells should also get affected by its deficiency?

They are less affected as they have a "mitochondrial source" of NADPH (from malic enzyme and isocitrate dehydrogenase activities) which RBC have not.

Thanks Dominique

Famous Late Prof. Dr. Tsuneo Okuyama (Faculty of Science, Tokyo Metropolitan University, Setagaya-ku, Tokyo, Japan) has purified NADH/NADPH dehydrogenase from bovine red blood cells or erythrocytes. Therefore, NADH dehydrogenase is present in both eucaryote and procaryote.

I have searched for G6PD among my protein database in vain (please see file; HepG2 Fucoidan). Therefore, G6P dehydrogenase seems to be only present in procaryote.

L-Lactate dehydrogenase in cytoplasm is present in humans, and this enzyme may produce NADH/NADPH by changing L-Lactate to Pyruvate. Pyruvate is important for the cells to alive (please see file; Dr. C-K Chern Agrobacterium).

Thus, prevention of oxidative stress in humans seems to be occurred in cytoplasmic enzymes. L-Lactate dehydrogenase produces NADH/NADPH, and NADH/NADPH reduces Glutathione.

We talk only about RBC when there is G6PD deficiency because it is the rate-limiting (key) enzyme in the Hexose Monophosphate Shunt or Pentose Phosphate Pathway. Normally, this enzyme bring about the production of NADPH, which in turn, reduces oxidized glathatione. Now, because the RBC functions in carrying oxygen from the lungs to the tissues, it becomes a target for Oxidative damage. However, oxidants produced during such metabolic activities are being taken care of by the reduced glathatione present in the RBC. But there is G6PD deficiency, NADPH and reduced glathatione won't be produced in reasonable amount, which will lead to haemolysis.

On the other hand, leukocytes and platelets get NADPH from sources other than G6PD.