Sunday, August 8, 2010

Food and Nutrition: Enzyme

A protein that catalyses a metabolic reaction, so increasing its rate. Enzymes are specific for both the compounds acted on (the substrates) and the reactions carried out. Because of this, enzymes extracted from plants, animals, or micro-organisms, or those produced by genetic manipulation are widely used in the chemical, pharmaceutical, and food industries (e.g. chymosin in cheese making, maltase in beer production, for synthesis of vitamin C and citric acid).


Because they are proteins, enzymes are permanently inactivated by heat, strong acid or alkali, and other conditions which cause denaturation of proteins.

Many enzymes contain non-protein components which are essential for their function. These are known as prosthetic groups, coenzymes, or cofactors, and may be metal ions, metal ions in organic combination (e.g. haem in haemoglobin and cytochromes) or a variety of organic compounds, many of which are derived from vitamins. The (inactive) protein without its prosthetic group is known as the apo-enzyme, and the active assembly of protein plus prosthetic group is the holo-enzyme. See also enzyme activation assays.

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