Apoenzyme vs. holoenzyme
An enzyme is inactive without its bound Mg²⁺ ion. The protein portion alone is called the:
Answer B: explanation for every choice
A
The holoenzyme is the complete, active enzyme with its cofactor bound.
B
Correct. The apoenzyme is the protein without its required cofactor.
C
A coenzyme is an organic cofactor, such as NAD⁺.
D
A zymogen is an inactive precursor that must be cleaved to become active.
TakeawayApoenzyme + cofactor = holoenzyme.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb27.