Which of the following is an example of non-competitive and reversible type inhibition?

Options

A. CN poisoning of cytochrome oxidase
B. Inhibition of hexokinase by glucose-6P
C. Inhibition of succinic dehydrogenase by malonate
D. (1) and (3) both

Answer

**Step-by-Step Solution:**

1. **Understanding Enzyme Inhibition:**
- Enzymes can be inhibited by various molecules that prevent them from catalyzing reactions. Inhibition can be classified into different types, including competitive, non-competitive, and irreversible inhibition.

2. **Identifying Non-Competitive Inhibition:**
- Non-competitive inhibition occurs when an inhibitor binds to an enzyme at a site other than the active site (known as the allosteric site). This binding changes the enzyme's shape, preventing the substrate from binding effectively to the active site.

3. **Reversibility of Inhibition:**
- In reversible inhibition, the inhibitor can dissociate from the enzyme, allowing the enzyme to regain its original shape and function. This is contrasted with irreversible inhibition, where the inhibitor permanently disables the enzyme.

4. **Analyzing the Options:**
- The options provided are:
1. Cyanide poisoning of cytochrome oxidase
2. Inhibition of hexokinase by glucose 6-phosphate
3. Inhibition of succinic dehydrogenase by malonate
4. 1N3 both

5. **Evaluating Each Option:**
- **Cyanide poisoning of cytochrome oxidase:** This is an irreversible inhibition.
- **Inhibition of hexokinase by glucose 6-phosphate:** This is a non-competitive and reversible inhibition. Glucose 6-phosphate binds to hexokinase, causing a conformational change that inhibits further conversion of glucose to glucose 6-phosphate.
- **Inhibition of succinic dehydrogenase by malonate:** This is a competitive inhibition as malonate competes with succinate for the active site.
- **1N3 both:** This option is unclear and does not specifically refer to a known type of inhibition.

6. **Conclusion:**
- The correct answer is **option 2: Inhibition of hexokinase by glucose 6-phosphate**, as it exemplifies non-competitive and reversible inhibition.