Biochemical mechanism through which G6PD protects red blood cells against oxidant damage

Simplified schema of the mechanism by which G6PD protects red blood cells against oxidant injury. Oxidants generate hydrogen peroxide (H₂O₂), which is converted to water (H₂O) in a reaction catalyzed by glutathione peroxidase (GPx) and associated with the conversion of reduced glutathione (GSH) to oxidized glutathione (GSSG). In red blood cells, GSH is regenerated in a reaction catalyzed by glutathione reductase (GSR) and associated with the conversion of NADPH to NADP. NADPH is regenerated in a reaction catalyzed by G6PD in which glucose-6-phosphate (G-6-P) is converted to 6-phosphogluconate (6-PG). The last reaction (conversion of G-6-P to 6-PG) is the initial step in the hexose monophosphate (or pentose phosphate) shunt.