Question

Given below are two statements: 
• [Statement (I):] Non-proteinaceous molecules associated with the enzymes are called cofactors. 
• [Statement (II):] The cofactors can be a metal ion or an organic molecule. 
In light of the above statements, choose the most appropriate answer from the options given below. 
 

• A. Both Statement (I) and Statement (II) are correct.
• B. Both Statement (I) and Statement (II) are incorrect.
• C. Statement (I) is correct but Statement (II) is incorrect.
• D. Statement (I) is incorrect but Statement (II) is correct.

Hint:

Remember the enzyme terminology equation:
\[ \text{Apoenzyme (protein)} + \text{Cofactor (non-protein)} = \text{Holoenzyme (active)} \] Coenzymes are a specific subset of organic cofactors.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Many enzymes require non-protein chemical components to catalyze reactions efficiently.
An intact, catalytically active enzyme-cofactor complex is called a holoenzyme, while the inactive protein component alone is called the apoenzyme.

Step 3: Detailed Explanation:
Let us evaluate both statements:
- Statement (I) is correct: A cofactor is defined as a non-proteinaceous chemical compound or metallic ion that binds to an apoenzyme, altering its structure to allow substrate binding and catalysis.
Without their required cofactors, these enzymes remain inactive.
- Statement (II) is correct: Cofactors are broadly classified into two categories:
1. Inorganic metal ions: These include trace elements like Fe$^{2+}$, Mg$^{2+}$, Zn$^{2+}$, Cu$^{2+}$, and Mn$^{2+}$, which stabilize the enzyme's structure or participate directly in redox reactions.
2. Organic molecules: These are carbon-based cofactors, further divided into:
- Coenzymes: Weakly associated, dialyzable organic molecules that transiently bind to the enzyme (such as NAD$^+$, NADP$^+$, and Coenzyme A).
- Prosthetic groups: Permanently and tightly linked organic molecules (such as the heme group in catalase or peroxidase).
Therefore, both Statement (I) and Statement (II) are correct.

Step 4: Final Answer:
Both Statement (I) and Statement (II) are correct, matching Option (A).