What is an enzyme together with its required cofactor called?

### Why this is right A holoenzyme is the complete catalytically active enzyme, consisting of the protein portion and its required nonprotein component. The nonprotein component may be a metal ion or an organic cofactor. ### The other options - **Apoenzyme**: the protein portion without its required cofactor; it is often inactive in that state. - **Zymogen**: an inactive enzyme precursor that requires activation. - **Inhibitor**: a molecule that reduces enzyme activity. ### Terms - **Cofactor**: a nonprotein component required for enzyme activity. ### Remember Apoenzyme plus required cofactor gives holoenzyme.