Final answer:
The committed step of the oxidative stage of the pentose phosphate pathway is catalyzed by G6PD, which is crucial for regulating NADPH production and maintaining cellular antioxidant balance.
Step-by-step explanation:
The committed step of the oxidative stage of the pentose phosphate pathway is catalyzed by glucose-6-phosphate dehydrogenase (G6PD). This enzyme plays a crucial role as it catalyzes the first reaction in the pathway, which regulates the production of NADPH, a co-enzyme essential in various cellular processes, including the maintenance of the antioxidant glutathione.
NADPH functions as an electron donor, helping to protect red blood cells and other cells from oxidative damage by maintaining the balance between the oxidized (GSSG) and reduced (GSH) forms of glutathione. Given its central role, the G6PD-catalyzed reaction is a regulatory point in the pentose phosphate pathway and is considered the committed step as it decides the entry of glucose-6-phosphate into this pathway versus glycolysis.