Calcium is required for functioning of enzyme

Options

A. Fumarase
B. ATP-ase
C. Succinate thiokinase
D. Isocitrate dehydrogenase.

Answer

**Step-by-Step Solution:**

1. **Understanding the Role of Calcium in Enzyme Functioning:**
- Calcium ions (Ca²⁺) are known to act as cofactors for certain enzymes, which means they assist in the enzyme's activity.

2. **Identifying the Enzymes Involved:**
- The question provides several options: fumarase, ATPase, succinate thiokinase, and isocitrate dehydrogenase. We need to determine which of these enzymes requires calcium for its activity.

3. **Analyzing Each Option:**
- **Fumarase:** This enzyme is involved in the Krebs cycle but does not require calcium ions for its activity. It catalyzes the conversion of fumarate to malate.
- **ATPase:** This enzyme is responsible for the hydrolysis of ATP to ADP and inorganic phosphate. It typically requires magnesium ions (Mg²⁺) as a cofactor, not calcium.
- **Succinate Thiokinase:** This enzyme catalyzes the conversion of succinyl CoA to succinate. It does not require calcium ions.
- **Isocitrate Dehydrogenase:** This enzyme is crucial in the Krebs cycle for the conversion of isocitrate to alpha-ketoglutarate. It requires calcium ions as a cofactor for its activity.

4. **Conclusion:**
- After analyzing all the options, we find that isocitrate dehydrogenase is the enzyme that requires calcium ions for its functioning. Therefore, the correct answer is **isocitrate dehydrogenase**.

**Final Answer:**
- The correct answer is **isocitrate dehydrogenase**.

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