Q.5 Non-active protein part of an enzyme that requires cofactor for activation is
1. apoenzyme
2. holoenzyme
3. coenzyme
4. ribozyme
The correct answer to the query is 1. apoenzyme, as it precisely describes the non-active protein component of an enzyme that requires a cofactor for activation. This concept is fundamental in biochemistry for understanding enzyme structure and function.
Correct Answer
1. Apoenzyme
Apoenzyme refers to the protein portion of an enzyme that is catalytically inactive on its own. It binds to a non-protein cofactor (organic coenzyme or inorganic ion) to form the active holoenzyme, enabling substrate specificity and reaction catalysis.
All Options Explained
| Option | Description | Why Correct/Incorrect |
|---|---|---|
| 1. Apoenzyme | Inactive protein part of the enzyme; requires cofactor for full activity. | Correct: Matches the query exactly – non-active protein needing cofactor. |
| 2. Holoenzyme | Complete, active enzyme (apoenzyme + cofactor). | Incorrect: This is the fully active form, not the inactive protein part. |
| 3. Coenzyme | Organic, non-protein cofactor (often vitamin-derived) that activates apoenzyme. | Incorrect: This is the non-protein activator, not the protein part. |
| 4. Ribozyme | RNA-based enzyme with catalytic activity; no protein component. | Incorrect: Catalytic RNA molecule, unrelated to protein-cofactor enzymes. |
Why Apoenzyme Matters
Apoenzymes ensure enzyme specificity, while cofactors provide chemical reactivity, as seen in DNA polymerase (needs Mg²⁺ cofactor). This distinction is key for exams like NEET or biochemistry courses.
