Question

S4b. If glucose-6-phosphate dehydrogenase is defective in cells, can cells still achieve one of the two main functions of the pentose phosphate pathway? Explain your answer.

Answer 1

Pentose phosphate pathway has two major functions - the formation of NADPH for synthesis of fatty acids and steroids, and maintaining reduced glutathione for antioxidant activity, and the synthesis of ribose for nucleotide and nucleic acid formation. Glucose-6-phosphate dehydrogenase in the pentose phosphate pathway converts glucose-6-phosphate into 6-phosphoglucono lactone and is the rate-limiting enzyme of the pathway that supplies NADPH. The NADPH in turn maintains the supply of reduced glutathione in the cells that is used to mop up free radicals that cause oxidative damage. When glucose-6-phosphate dehydrogenase is deficient and since G6PD / NADPH pathway is the only source of reduced glutathione, none of the glutathione will be produced. Also, none of the pentose will be produced via the oxidative pathway.