Identify A and B in the given reaction.
Pyruvic acid `+CoA + NAD^(+) overset(Mg^(2+))underset("Pyruvate dehydrogenase")rarr A+B +NADH +H^(+)`

Options

A. `A - PEP , B - CO_2`
B. A - Acetyl `CoA , B - CO_2`
C. `A - CO_2 , B - H_2O`
D. A - Acetyl CoA , `B - H_2O`

Answer

To identify A and B in the given reaction, we will analyze the components and process involved in the reaction step by step.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
The reaction provided is:
\[ \text{Pyruvic acid} + \text{CoA} + \text{NAD}^+ \overset{\text{Mg}^{2+}}{\underset{\text{Pyruvate dehydrogenase}}{\rightarrow}} A + B + \text{NADH} + \text{H}^+ \]
Here, pyruvic acid (a 3-carbon molecule) is being converted into products A and B in the presence of CoA, NAD+, magnesium ions, and the enzyme pyruvate dehydrogenase.

2. **Identifying the Process**:
This reaction is known as oxidative decarboxylation. During this process, one carbon atom is removed from pyruvic acid in the form of carbon dioxide (CO2), resulting in a 2-carbon compound.

3. **Determining Product B**:
Since one carbon is released as carbon dioxide during the reaction, we can conclude that:
\[ B = \text{CO}_2 \]

4. **Determining Product A**:
The remaining 2-carbon compound after the decarboxylation of pyruvic acid is known as acetyl coenzyme A (acetyl-CoA). Therefore, we can conclude that:
\[ A = \text{Acetyl CoA} \]

5. **Final Identification**:
Thus, we have identified:
- A = Acetyl Coenzyme A (Acetyl-CoA)
- B = Carbon Dioxide (CO2)

### Conclusion:
The correct identification of A and B in the reaction is:
- A = Acetyl Coenzyme A
- B = Carbon Dioxide