Question

The protein part of an enzyme is called _______

• A. Apoenzyme
• B. Coenzyme
• C. Holoenzyme
• D. Cofactor

Hint:

Apoenzyme is the protein part; cofactor is the non-protein part; holoenzyme is the complete active enzyme.

Answer 1

The Correct Option is A

Concept:
Some enzymes require a non-protein component for activity. Such enzymes have a protein part and a non-protein part.

Step 1: Definition of apoenzyme.
The protein part of an enzyme is called apoenzyme.

Step 2: Definition of cofactor.
The non-protein part required for enzyme activity is called a cofactor.

Step 3: Definition of holoenzyme.
When apoenzyme combines with its cofactor, the complete active enzyme is called holoenzyme. \[ \text{Apoenzyme} + \text{Cofactor} = \text{Holoenzyme} \]

Step 4: Checking other options.
Coenzyme is an organic non-protein cofactor.
Cofactor may be organic or inorganic.
Holoenzyme is the complete active enzyme.
Apoenzyme is the protein part.

Step 5: Final answer.
Therefore, the protein part of an enzyme is called apoenzyme. \[ \boxed{\text{Apoenzyme}} \]