Which one undergoes decarboxylation in hexose monophosphate shunt

Options

A. Glucose 6-phosphate
B. `6-glucono gamma-lactone`
C. 6-phosphogluconate
D. Fructose 6- phosphate

Answer

### Step-by-Step Solution:

1. **Understanding the Hexose Monophosphate Shunt**: The hexose monophosphate shunt, also known as the pentose phosphate pathway (PPP), is a metabolic pathway parallel to glycolysis that generates NADPH and pentoses (5-carbon sugars).

2. **Identifying the Process**: In the PPP, glucose-6-phosphate is converted into ribulose-5-phosphate through a series of reactions. One of the key steps in this pathway involves the conversion of 6-phosphogluconate.

3. **Decarboxylation Process**: Decarboxylation is a chemical reaction that involves the removal of a carboxyl group (COOH) and releases carbon dioxide (CO2). In the context of the PPP, this occurs when 6-phosphogluconate is converted into ribulose-5-phosphate.

4. **Key Reaction**: The specific reaction that involves decarboxylation is:
\[ 6\text{-phosphogluconate} \rightarrow \text{ribulose-5-phosphate} + \text{CO}_2 \]
This indicates that during the conversion of 6-phosphogluconate, carbon dioxide is released.

5. **Conclusion**: Based on the above analysis, the compound that undergoes decarboxylation in the hexose monophosphate shunt is **6-phosphogluconate**.

### Final Answer:
The compound that undergoes decarboxylation in the hexose monophosphate shunt is **6-phosphogluconate**.

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