Which of the following statement is not true for allosteric inhibition?

Options

A. Inhibitor has no structural similarity with the substrate
B. It is irreversible
C. Inhibitor attaches to an area other than active site
D. Conformation of enzymes is changed

Answer

To determine which statement is not true for allosteric inhibition, we need to analyze each of the provided options regarding allosteric inhibition.

### Step-by-Step Solution:

1. **Understanding Allosteric Inhibition**:
Allosteric inhibition refers to the process where an inhibitor binds to an enzyme at a site other than the active site, leading to a change in the enzyme's conformation and reducing its activity.

2. **Analyzing the Options**:
- **Option A**: "The inhibitor has no structural similarity with the substrate."
- This statement is **true**. Allosteric inhibitors are typically structurally different from the substrate they inhibit.

- **Option B**: "It is irreversible."
- This statement is **not true**. Allosteric inhibition is generally a reversible process. The inhibitor can detach from the enzyme, allowing the enzyme to regain its activity.

- **Option C**: "Inhibitor attaches to an area other than the active site."
- This statement is **true**. By definition, allosteric inhibitors bind to sites other than the active site.

- **Option D**: "A conformation of the enzyme is changed."
- This statement is **true**. The binding of the allosteric inhibitor causes a change in the enzyme's shape, affecting its function.

3. **Conclusion**:
The statement that is not true for allosteric inhibition is **Option B**, which claims that allosteric inhibition is irreversible.

### Final Answer:
The statement that is not true for allosteric inhibition is **Option B: It is irreversible.**

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