Explanatory notes
… living cells, without themselves undergoing any change in their chemical structure. Enzymes may be referred to as … : (a) Enzymes in which the molecule consists solely of a protein (e.g., pepsin, trypsin, urease). (b) Enzymes in … weight, acting as a cofactor. The cofactor may be either a metal ion (e.g., copper in ascorbate oxidase, zinc …