The coenzyme involved in oxidative decarboxylation is

Options

A. Thiamine pyrophosphate
B. Biotin
C. NAD
D. Pyridoxal phosphate.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the coenzyme involved in oxidative decarboxylation. Oxidative decarboxylation is a biochemical process that involves the removal of a carboxyl group from a molecule, releasing carbon dioxide, and is coupled with oxidation.

2. **Identifying the Process**: This process is notably present in the Krebs cycle (also known as the citric acid cycle), which is a key metabolic pathway that generates energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins.

3. **Recognizing Key Coenzymes**: In the context of oxidative decarboxylation, several coenzymes are involved:
- Thiamine pyrophosphate (TPP)
- NAD (Nicotinamide adenine dinucleotide)
- Lipoic acid
- Coenzyme A (CoA)

4. **Specific Reaction**: The specific reaction in the Krebs cycle that involves oxidative decarboxylation is the conversion of alpha-ketoglutarate to succinyl-CoA. This reaction requires TPP and NAD as coenzymes.

5. **Conclusion**: Based on the above information, the coenzyme specifically involved in oxidative decarboxylation is Thiamine pyrophosphate (TPP). Additionally, NAD is also involved in the process.

6. **Final Answer**: The coenzyme involved in oxidative decarboxylation is Thiamine pyrophosphate (TPP), and NAD is also a correct answer in the context of the Krebs cycle.

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