Isocitric acid is changed to 2-oxoglutaric acid by

Options

A. Oxidative carboxylation
B. Oxidative decarboxylation
C. Dehydrogentaion
D. Hydrogentaion and decarboxylation.

Answer

To determine how isocitric acid is converted to 2-oxoglutaric acid, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reaction Context**: The conversion of isocitric acid to 2-oxoglutaric acid occurs within the Krebs cycle, also known as the citric acid cycle.

2. **Recognize the Substrates**: Isocitric acid, also known as isocitrate, is the starting compound, and 2-oxoglutaric acid is also referred to as alpha-ketoglutarate.

3. **Initial Conversion**: The first step in the conversion involves the enzyme isocitrate dehydrogenase. This enzyme catalyzes the conversion of isocitrate to oxalosuccinic acid.

4. **Oxidation Reaction**: During this conversion, a hydrogen ion is released, which reduces NAD+ to NADH. This step is crucial as it indicates that oxidation is taking place.

5. **Decarboxylation Step**: The next step involves the conversion of oxalosuccinic acid to 2-oxoglutaric acid. This reaction is catalyzed by the enzyme oxalosuccinic decarboxylase.

6. **Release of Carbon Dioxide**: In this step, one molecule of carbon dioxide (CO2) is released, indicating that decarboxylation is occurring.

7. **Final Product**: After these reactions, the final product is 2-oxoglutaric acid (alpha-ketoglutarate).

8. **Conclusion**: The overall process can be summarized as oxidative decarboxylation, where isocitric acid is converted to 2-oxoglutaric acid through a series of enzymatic reactions involving oxidation and decarboxylation.

### Final Answer:
Isocitric acid is changed to 2-oxoglutaric acid by oxidative decarboxylation.

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