Dehydrogenases of HMP shunt are specific for:
## **Core Concept**
The Hexose Monophosphate (HMP) shunt, also known as the Pentose Phosphate Pathway (PPP), is a metabolic pathway parallel to glycolysis. It generates NADPH and pentoses from glucose-6-phosphate. The dehydrogenases specific to the HMP shunt are crucial for its function.
## **Why the Correct Answer is Right**
The correct answer, **D. NADP+**, is right because the dehydrogenases of the HMP shunt, specifically glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase, are unique in that they require NADP+ as a coenzyme. NADP+ is reduced to NADPH during the oxidative phase of the HMP shunt. This specificity for NADP+ allows the HMP shunt to produce NADPH, which is essential for biosynthetic reactions, including fatty acid synthesis, cholesterol synthesis, and antioxidant defenses.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because it does not specify a correct coenzyme or substrate specific to the dehydrogenases of the HMP shunt.
- **Option B:** This option is incorrect as it does not accurately represent the specificity of HMP shunt dehydrogenases.
- **Option C:** This option is incorrect because, similar to option A, it does not accurately specify the correct coenzyme or substrate for the dehydrogenases of the HMP shunt.
## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that deficiencies in G6PD, one of the dehydrogenases in the HMP shunt, can lead to hemolytic anemia due to the reduced ability of red blood cells to generate NADPH. This makes them more susceptible to oxidative damage. Mnemonically, recall that "G6PD" deficiency is associated with "Heinz bodies" in red blood cells.
## **Correct Answer:** D. NADP+.