CHEMISTRY GLOSSARY

Enzyme is a protein that acts as a catalyst in biochemical reactions. Each enzyme is specific to a particular reaction or a group of similar reactions. Many require the association of certain nonprotein cofactors in order to function. The molecule undergoing a reaction (the substrate) binds to a specific active site on the enzyme molecule to form a short-lived intermediate: this greatly increases (by a factor of up to 10²⁰) the rate at which the reaction proceeds to form the product.