Allosteric modulation is due to inhibition of coenzyme action by

Options

A. Competitive inhibition
B. Substrate concentration
C. Product of reaction
D. Non-competitive inhibition.

Answer

### Step-by-Step Solution

1. **Understanding Allosteric Modulation**:
- Allosteric modulation refers to the regulation of an enzyme's activity through the binding of an effector molecule at a site other than the active site. This can lead to either inhibition or activation of the enzyme.

2. **Feedback Inhibition**:
- Allosteric modulation is often associated with feedback inhibition. In feedback inhibition, the end product of a metabolic pathway inhibits an earlier step in the pathway, thereby regulating the overall process.

3. **Role of the Product**:
- In feedback inhibition, the product of a metabolic reaction acts as an inhibitor. This product binds to a regulatory site on the enzyme, which alters the enzyme's shape and function, inhibiting its activity.

4. **Example of Feedback Inhibition**:
- A classic example is glucose 6-phosphate acting as an inhibitor for the enzyme hexokinase. When glucose 6-phosphate accumulates, it binds to hexokinase, inhibiting its action and thus reducing the conversion of glucose to glucose 6-phosphate.

5. **Differentiating Types of Inhibition**:
- **Competitive Inhibition**: In this type, the inhibitor competes with the substrate for the active site of the enzyme. If the inhibitor binds, no product is formed.
- **Non-Competitive Inhibition**: Here, the inhibitor can bind to the enzyme regardless of whether the substrate is present, leading to no product formation, but it does not compete with the substrate for the active site.

6. **Conclusion**:
- The correct answer to the question is that allosteric modulation is due to the inhibition of enzyme action by the product of the reaction, which acts as an inhibitor.