Nickel is component of

Options

A. PEP carboxylase
B. Rubisco
C. Urease
D. Nitrate reductase.

Answer

To determine which enzyme contains nickel as a component, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Identify the Options**: The options given are:
- PEP carboxylase
- Rubisco
- Urease
- Nitrate reductase

2. **Analyze PEP Carboxylase**:
- PEP carboxylase is an enzyme that catalyzes the conversion of carbon dioxide into bicarbonate and subsequently into oxaloacetic acid.
- **Conclusion**: Nickel is not a component of PEP carboxylase. (Incorrect option)

3. **Analyze Rubisco**:
- Rubisco (Ribulose-1,5-bisphosphate carboxylase/oxygenase) is the most abundant enzyme on Earth and plays a crucial role in carbon fixation during photosynthesis.
- **Conclusion**: Nickel is not a component of Rubisco. (Incorrect option)

4. **Analyze Urease**:
- Urease is an enzyme that catalyzes the hydrolysis of urea into ammonia and carbon dioxide.
- Importantly, urease is known to be a nickel-containing metalloprotein.
- **Conclusion**: Nickel is indeed a component of urease. (Correct option)

5. **Analyze Nitrate Reductase**:
- Nitrate reductase is an enzyme involved in nitrogen fixation, converting nitrate to nitrite.
- **Conclusion**: Nickel is not a component of nitrate reductase. (Incorrect option)

6. **Final Conclusion**:
- Based on the analysis, the correct answer is **Urease**, as it is the only enzyme listed that contains nickel as a component.