Apoenzyme plus a prosthetic group forms which enzyme type?

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

Answer: (A)

The active form of an enzyme is created when the protein part, called the apoenzyme, binds a non-protein component that is tightly attached, known as a prosthetic group. This combination produces the holoenzyme, which is the fully functional enzyme capable of catalysis. The apoenzyme by itself is inactive, and the prosthetic group is not an enzyme on its own. A cofactor is the general term for non-protein components that assist enzyme activity (prosthetic groups are a type of cofactor that remains tightly bound). Isoenzymes are different enzymes that catalyze the same reaction in different tissues. Therefore, apoenzyme plus a prosthetic group forms the holoenzyme.