In Krebs cycle, malate hands over hydrogen to

Options

A. `NAD^(+)`
B. FAD
C. FMN
D. Oxaloacetate

Answer

**Step-by-Step Solution:**

1. **Understanding the Krebs Cycle**: The Krebs cycle, also known as the citric acid cycle or tricarboxylic acid cycle, occurs in the mitochondrial matrix. It is a crucial part of cellular respiration where energy is produced.

2. **Key Reactants and Products**: The cycle begins with acetyl coenzyme A combining with oxaloacetate to form citrate. The cycle then progresses through several transformations, producing key intermediates like isocitrate, alpha-ketoglutarate, succinyl coenzyme A, succinate, fumarate, and finally regenerating oxaloacetate.

3. **Focus on Malate**: One of the steps in the Krebs cycle involves the conversion of malate to oxaloacetate. This step is catalyzed by the enzyme malate dehydrogenase.

4. **Role of Malate Dehydrogenase**: During this conversion, malate is oxidized to form oxaloacetate. In this process, malate donates hydrogen (H) to a coenzyme.

5. **Identifying the Coenzyme**: The coenzyme that accepts the hydrogen from malate is NAD⁺ (Nicotinamide adenine dinucleotide). When malate donates hydrogen to NAD⁺, NAD⁺ is reduced to NADH.

6. **Conclusion**: Therefore, in the Krebs cycle, malate hands over hydrogen to NAD⁺, resulting in the formation of NADH and the conversion of malate to oxaloacetate.

**Final Answer**: NAD⁺ (Option 1).

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