Enzyme helping in oxidative decarboxylation of pyruvate is

Options

A. (a) pyruvate kinase
B. (b) pyruvate dehydrogenase
C. (c) succinic dehydrogenase
D. (d) pyruvate oxidase

Answer

**Step-by-Step Solution:**

1. **Understanding the Reaction**: The question asks for the enzyme responsible for the oxidative decarboxylation of pyruvate. This reaction involves the removal of carbon dioxide (CO2) and the oxidation of pyruvate, which results in the formation of NADH.

2. **Location of the Reaction**: This reaction occurs in the mitochondria and serves as a crucial link between glycolysis (the breakdown of glucose) and the Krebs cycle (the citric acid cycle).

3. **Analyzing the Options**:
- **Option A: Pyruvate Kinase**: This enzyme catalyzes the conversion of phosphoenolpyruvate to pyruvate, which is the final step of glycolysis. It occurs in the cytosol and does not involve the release of CO2 or the formation of NADH. Therefore, this option is incorrect.

- **Option B: Pyruvate Dehydrogenase**: This enzyme is a complex consisting of multiple components (E1, E2, and E3) and catalyzes the conversion of pyruvate to acetyl-CoA. This reaction occurs in the mitochondria, releases NADH, and removes CO2, making it the connecting reaction between glycolysis and the Krebs cycle. This option is likely the correct answer.

- **Option C: Succinic Dehydrogenase**: This enzyme converts succinate to fumarate in the Krebs cycle. While it operates in the mitochondria, it does not involve the decarboxylation of pyruvate or the release of CO2. Thus, this option is incorrect.

- **Option D: Pyruvate Oxidase**: This enzyme converts pyruvate to acetyl phosphate and involves the removal of CO2. However, it also includes a phosphorylation reaction, which is not relevant to the question. Therefore, this option is also incorrect.

4. **Conclusion**: After analyzing all options, the only enzyme that fits the criteria of catalyzing the oxidative decarboxylation of pyruvate, occurring in the mitochondria, releasing NADH, and removing CO2 is **pyruvate dehydrogenase**.

**Final Answer**: The enzyme helping in oxidative decarboxylation of pyruvate is **pyruvate dehydrogenase**.

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