Enzymes belong to a group of macromolecules called proteins. The basic function of an enzyme is to control the rate of chemical reactions by acting as a biological catalyst.
Proteins are synthesized by bonding amino acids into a chain. The shape and function of an enzyme is determined directly by the order of amino acids present. High heat denatures proteins by preventing them from folding to the correct shape. Therefore, each enzyme has an optimum temperature that is high enough to allow chemical reactions but low enough to prevent denaturing. Generally, enzymes are recognized by the suffix "-ase." Three other groups of macromolecules exist: carbohydrates, lipids and nucleic acids.