Malonate is a competitive inhibitor of
**Core Concept**
The question tests understanding of enzyme inhibition, specifically competitive inhibition. Competitive inhibitors compete with the substrate for binding to the active site of the enzyme. **Succinate dehydrogenase** is an enzyme involved in the citric acid cycle.
**Why the Correct Answer is Right**
Malonate is a competitive inhibitor because its structure is similar to that of succinate, allowing it to bind to the active site of **succinate dehydrogenase**. This binding prevents succinate from accessing the active site, thereby reducing the enzyme's activity. The inhibition is reversible, meaning that increasing the concentration of succinate can outcompete malonate for the active site.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because malonate does not inhibit this enzyme.
**Option B:** Incorrect as it is not related to malonate's inhibitory action.
**Option C:** Incorrect because malonate does not act on this target.
**Option D:** This is the correct answer, so it's not incorrect.
**Clinical Pearl / High-Yield Fact**
Remember that competitive inhibitors can be overcome by increasing the substrate concentration, which is a key concept in pharmacology and biochemistry.
**Correct Answer:** D. Succinate dehydrogenase