Question

Why does it make metabolic sense for Isocitrate Dehydrogenase in the human TCA cycle to use NADP+ instead of NAD+?

a. Evolutionary adaptation for growth in acetate.
b. Efficient NADH production in oxidative pentose phosphate pathway.
c. NADP+ favored for reductive metabolism.
d. All of the above.

Answer 1

Isocitrate Dehydrogenase uses NADP+ instead of NAD+ because NADP+ is favored for reductive metabolism.

Step-by-step explanation:

The reason Isocitrate Dehydrogenase in the human TCA cycle uses NADP+ instead of NAD+ is because NADP+ is favored for reductive metabolism. Isocitrate Dehydrogenase catalyzes the conversion of isocitrate to α-ketoglutarate, generating NADPH in the process.

NADPH is an important reducing agent in many metabolic pathways, including fatty acid and cholesterol synthesis. It is used to donate high-energy electrons to biosynthetic reactions.

Therefore, the correct answer is c. NADP+ favored for reductive metabolism.