<biochemistry> A protein molecule produced by living organisms that catalyses chemical reactions of other substances without itself being destroyed or altered upon completion of the reactions.

Enzymes are classified according to the recommendations of the Nomenclature Committee of the International Union of Biochemistry. Each enzyme is assigned a recommended name and an Enzyme Commission (EC) number.

They are divided into six main groups, oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases.

(09 Oct 1997)