An example of Competitive inhibitor is :

Options

A. Succinic dehydrogenase and malonate
B. Hexokinase by glucose 6 phosphate
C. Cytochrome oxidase /Cyanide
D. More than one option is correct

Answer

To solve the question regarding an example of a competitive inhibitor, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Competitive Inhibition**:
- Competitive inhibition occurs when a molecule that resembles the substrate competes with the substrate for binding to the active site of an enzyme. This means that the inhibitor and the substrate are structurally similar enough that they can both bind to the same site on the enzyme.

2. **Identify the Enzyme and Substrate**:
- In the context of the question, we need to identify an enzyme and its substrate. For example, succinate dehydrogenase is an enzyme, and its substrate is succinate.

3. **Identify the Competitive Inhibitor**:
- A competitive inhibitor will have a structure similar to that of the substrate. In this case, malonate is a molecule that resembles succinate and can bind to the active site of succinate dehydrogenase.

4. **Evaluate the Options**:
- The question provides multiple options. We need to evaluate each option to determine if it represents a case of competitive inhibition:
- **Option 1**: Succinate dehydrogenase and malonate - This is a correct example of competitive inhibition.
- **Option 2**: Hexokinase and glucose 6-phosphate - This is not competitive inhibition; it is an example of allosteric inhibition.
- **Option 3**: Cytochrome oxidase and cyanide - This is an example of non-competitive inhibition.

5. **Conclusion**:
- After evaluating the options, the correct answer is **Option 1: Succinate dehydrogenase and malonate**, as malonate competes with succinate for the active site of the enzyme.

### Final Answer:
The example of a competitive inhibitor is **Succinate dehydrogenase and malonate**.

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