Question

The non-protein part of an enzyme is a

• A. Prosthetic group.
• B. Coenzyme.
• C. Cofactor.
• D. All of the above.

Answer 1

The correct option is D All of the above.

Enzymes are protein, some enzymes require no chemical groups for activity other than their amino acid residues. Others require an additional chemical component called a cofactor, either one or more inorganic ions, such as Fe${}^{2+}$, Mg${}^{2+}$, Mn${}^{2+}$, or Zn${}^{2+}$, or a complex organic or metallo-organic molecule called a coenzyme. Some enzymes require both a coenzyme and one or more metal ions for activity. A coenzyme or metal ion that is very tightly or even covalently bound to the enzyme protein is called a prosthetic group. A complete, catalytically active enzyme together with its bound coenzyme and/or metal ions is called a holoenzyme. The protein part of such an enzyme is called the apoenzyme or apoprotein. Coenzymes act as transient carriers of specific functional groups. Most are derived from vitamins, organic nutrients required in small amounts in the diet.