Concept:Many complex enzymes (holoenzymes) require an auxiliary, non-protein component to facilitate the catalytic reaction.
Formula:$$ \text{Apoenzyme (protein)} + \text{Cofactor (non-protein)} \rightarrow \text{Holoenzyme (active)} $$
Solution:- The protein portion of the enzyme is the apoenzyme.
- The non-protein portion required for activity is broadly called a cofactor.
- When this non-protein part is specifically an organic molecule (often derived from vitamins, like NAD+ or FAD), it is referred to as a co-enzyme.
Why other options are incorrect:The apoenzyme is the protein part, not the non-protein part. The substrate is the target molecule being acted upon. An activator is a substance that increases activity, but "co-enzyme" strictly defines the intrinsic non-protein prosthetic/helper group.
Quality & Fidelity Assurance:
Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.