In the Hatch & Slack cycle, the enzyme required to convert pyruvate into phosphoenol pyruvate is

Options

A. Pyruvate dehydrogenase
B. PEP carboxylase
C. Phosphoenol pyruvate dikinase
D. Phosphoenol pyruvate kinase

Answer

To solve the question regarding the enzyme required to convert pyruvate into phosphoenolpyruvate (PEP) in the Hatch & Slack cycle, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reaction**: The question asks for the enzyme that converts pyruvate to phosphoenolpyruvate (PEP). This is a crucial step in the Hatch & Slack cycle, which is a pathway for carbon fixation in plants.

2. **Review Enzymes**: We need to consider the enzymes involved in the conversion of pyruvate to PEP. The options provided in the video transcript include:
- Pyruvate dehydrogenase
- PEP carboxylase
- Phosphoenolpyruvate carboxykinase (often abbreviated as PEPCK)
- Phosphoenolpyruvate kinase

3. **Eliminate Incorrect Options**:
- **Pyruvate dehydrogenase**: This enzyme converts pyruvate into acetyl-CoA, not PEP.
- **PEP carboxylase**: This enzyme is involved in converting oxaloacetate into PEP, not directly from pyruvate.
- **Phosphoenolpyruvate kinase**: This enzyme works in the reverse direction, converting PEP to pyruvate.

4. **Identify the Correct Enzyme**: The enzyme that specifically converts pyruvate into phosphoenolpyruvate is **Phosphoenolpyruvate carboxykinase (PEPCK)**. This enzyme catalyzes the conversion of pyruvate to PEP through a carboxylation reaction.

5. **Conclusion**: Therefore, the enzyme required to convert pyruvate into phosphoenolpyruvate in the Hatch & Slack cycle is **Phosphoenolpyruvate carboxykinase (PEPCK)**.

### Final Answer:
The enzyme required to convert pyruvate into phosphoenolpyruvate in the Hatch & Slack cycle is **Phosphoenolpyruvate carboxykinase (PEPCK)**.