Malonate is inhibited by succinate dehydrogenase. This is a type of

Options

A. non-competitive inhibition
B. competitive inhibition
C. negative feed back
D. allosteric inhibition

Answer

To solve the question regarding the type of inhibition caused by malonate on succinate dehydrogenase, we can follow these steps:

### Step 1: Understand the Role of Succinate Dehydrogenase
Succinate dehydrogenase is an enzyme that catalyzes the conversion of succinate to fumarate in the citric acid cycle. It is crucial for cellular respiration.

**Hint:** Remember that enzymes facilitate reactions by binding to substrates at their active sites.

### Step 2: Identify the Inhibitor
Malonate is a compound that resembles succinate, the substrate for succinate dehydrogenase. It competes with succinate for binding to the active site of the enzyme.

**Hint:** Look for compounds that mimic the substrate and can bind to the enzyme's active site.

### Step 3: Determine the Type of Inhibition
Since malonate competes with succinate for the active site of succinate dehydrogenase, this type of inhibition is characterized by the inhibitor (malonate) directly competing with the substrate (succinate). This is known as competitive inhibition.

**Hint:** Competitive inhibition occurs when an inhibitor competes with the substrate for the active site, affecting the enzyme's ability to form products.

### Step 4: Analyze the Effects on Kinetics
In competitive inhibition, the maximum velocity (Vmax) of the reaction remains unchanged, but the apparent affinity of the enzyme for the substrate decreases, which is reflected in an increased Michaelis constant (KM).

**Hint:** Remember that in competitive inhibition, Vmax stays the same, but KM increases due to competition for the active site.

### Step 5: Review Other Types of Inhibition
- **Non-competitive inhibition**: The inhibitor binds to a site other than the active site, and this does not affect substrate binding.
- **Negative feedback**: A product of a reaction inhibits an earlier step in the pathway.
- **Allosteric inhibition**: Involves binding at a site other than the active site, leading to a change in enzyme activity.

**Hint:** Differentiate between competitive and non-competitive inhibition based on where the inhibitor binds.

### Conclusion
Based on the analysis, malonate acts as a competitive inhibitor of succinate dehydrogenase.

**Final Answer:** Competitive inhibition.