Question

Which one of the following undergoes decarboxylation in hexose monophosphate shunt?

• A. Glucose 6-phosphate
• B. 6-glucono $\gamma$-lactone
• C. 6-phosphogluconate
• D. Fructose 6-phosphate

Answer 1

The correct option is C 6-phosphogluconate

Hexose monophosphate shunt is an alternative pathway of glucose metabolism which starts with the dehydrogenation of glucose 6-phosphate to 6-phosphogluconate by the enzyme glucose-6-phosphate dehydrogenase. In this step, NADP is reduced to NADPH. In the next step, 6-phosphogluconate is decarboxylated to ribulose-5-phosphate which is again coupled to reduction of NADP to NADPH. Thus overall in the oxidative phase of hexose monophosphate shunt, 1 molecule of glucose-6-phosphate produces 1 molecule of ribulose-5-phosphate, 1 molecule of carbon dioxide and 2 molecules of reduced NADPH.

Thus, the correct answer is option C.