Accumulation of glucose 6-`PO_(4)` inhibits the activity of glucohexokinase. This is an example of

Options

A. Allosteric inhibition
B. Feed back inhibition
C. Retro inhibition
D. All of these

Answer

To solve the question regarding the inhibition of glucohexokinase by glucose-6-phosphate, we can break it down step by step:

### Step 1: Understand the Role of Glucohexokinase
Glucohexokinase is an enzyme that catalyzes the phosphorylation of glucose to glucose-6-phosphate. This reaction is crucial in glucose metabolism.

**Hint:** Identify the function of the enzyme involved in the question.

### Step 2: Identify the Inhibitor
In this case, glucose-6-phosphate is the product of the reaction catalyzed by glucohexokinase. When there is an accumulation of glucose-6-phosphate, it indicates that the enzyme's activity is being regulated.

**Hint:** Recognize the substance that is causing the inhibition and its relationship to the enzyme's activity.

### Step 3: Determine the Type of Inhibition
- **Allosteric Inhibition:** This occurs when an inhibitor binds to a site other than the active site of the enzyme, causing a change in the enzyme's shape and reducing its activity. Glucose-6-phosphate can bind to an allosteric site on glucohexokinase.

- **Feedback Inhibition:** This is a regulatory mechanism where the end product of a metabolic pathway inhibits an earlier step in the pathway. Since glucose-6-phosphate is the end product of the reaction catalyzed by glucohexokinase, it inhibits the enzyme, which is a classic example of feedback inhibition.

- **Retro Inhibition:** This term is often used interchangeably with allosteric inhibition, where the end product of a pathway inhibits an enzyme involved in its synthesis.

**Hint:** Analyze the definitions of different types of inhibition and see how they apply to the scenario presented.

### Step 4: Evaluate the Options
Given the definitions:
- Glucose-6-phosphate acts as an allosteric inhibitor.
- It also exemplifies feedback inhibition since it is the end product of the reaction.
- Retro inhibition is similar to allosteric inhibition.

Thus, all options (Allosteric inhibition, Feedback inhibition, and Retro inhibition) are applicable in this context.

**Hint:** Consider whether multiple types of inhibition can apply to the same scenario.

### Step 5: Conclusion
The correct answer is that the accumulation of glucose-6-phosphate inhibiting glucohexokinase is an example of all of the mentioned types of inhibition.

**Final Answer:** D) All of these.