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enzyme
(enīzīm)
any protein that acts as a catalyst, increasing the rate at which a chemical reaction occurs; there are at least 10,000 in the human body. At body temperature,
very few biochemical reactions proceed at a significant rate without the presence of an enzyme. Like other catalysts, enzymes do not control the direction of their reactions, but rather increase the rates of the forward and reverse reactions.
They work by binding molecules in a particular geometric configuration that allows the reaction to occur. Enzymes are very
specific, with only a few molecules that closely fit the binding site, so that each enzyme catalyzes a specific type of chemical
reaction involving a few closely related compounds (called substrates of the enzyme).
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