Nickel in an essential part of which of the following enzymes:

Options

A. Urease
B. Nitrogenase
C. Nitrate reductase
D. PEP carboxy las

Answer

To determine which enzyme contains nickel as an essential part, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Enzymes Listed**: The question provides four enzymes: Urease, Nitrogenase, Nitrate reductase, and PEP Carboxylase.

2. **Understand the Role of Nickel**: Nickel is classified as a micronutrient for plants, meaning it is required in small amounts. It plays a crucial role in certain enzymatic functions.

3. **Research Each Enzyme**:
- **Urease**: This enzyme catalyzes the hydrolysis of urea into ammonia and carbon dioxide. It is known to contain nickel as a cofactor.
- **Nitrogenase**: This enzyme is involved in the fixation of atmospheric nitrogen into ammonia. It primarily contains molybdenum or iron, but not nickel.
- **Nitrate Reductase**: This enzyme reduces nitrate to nitrite and typically contains molybdenum or tungsten, not nickel.
- **PEP Carboxylase**: This enzyme is involved in the fixation of carbon dioxide and does not contain nickel.

4. **Conclusion**: Based on the research, Urease is the enzyme that contains nickel as an essential part.

5. **Final Answer**: Therefore, the correct answer to the question is **Urease**.