Enzyme

An enzyme (from Greek ?nsimo (??????), formed by ?n = at or in and simo = leaven or yeast) is a protein that catalyzes, or speeds up, a chemical reaction.

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Enzymes are essential to sustain life, because most chemical reactions in biological cells would occur too slowly or would lead to different products without enzymes. A malfunction (mutation, overproduction, underproduction or deletion) of a single critical enzyme can lead to severe diseases. For example, phenylketonuria is caused by an enzyme malfunction in the enzyme phenylalanine hydroxylase, which catalyses the first step in the degradation of phenylalanine. If this enzyme does not function, the resulting build-up of phenylalanine leads to mental retardation.

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Like all catalysts, enzymes work by lowering the activation energy of a reaction, thus allowing the reaction to proceed much faster. Enzymes may speed up reactions by a factor of many thousands. An enzyme, like any catalyst, remains unaltered by the completed reaction and can therefore continue to function. Because enzymes, like all catalysts, do not affect the relative energy between the products and reagents, they do not affect equilibrium of a reaction. However, the advantage of enzymes compared to most other catalysts is their sterio-, regio- and chemoselectivity and specificity.

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Enzyme activity can be affected by other molecules. Inhibitors are molecules that decrease or abolish enzyme activity; activators are molecules that increase the activity. Suicide inhibitors are inhibitors that incorporate themselves into the enzyme, permanently deactivating it. Inhibitors can be either natural or man-made. Many drugs are enzyme inhibitors. Aspirin, for example, inhibits an enzyme that produces the inflammation messenger prostaglandin, thus suppressing pain and inflammation.

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Enzymes are also used in everyday products such as washing detergents, where they speed up chemical reactions involved in cleaning the clothes (for example, breaking down starch stains). For industrial purposes the properties of Enzymes are emulated to form new kinds of catalytic molecules named Synzymes and Abzyme.

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More than 5,000 enzymes are known. To name different enzymes, one typically uses the ending -ase with the name of the chemical being transformed (substrate), e.g., lactase is the enzyme that catalyzes the cleavage of lactose.

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Greek: The noun Greek refers to:...

Leaven: REDIRECT Leavening agent...

Yeast: Yeasts constitute a group of single-celled (unicellular) fungi, a few species of which are commonly used to leaven bread and ferment alcoholic beverages. Most yeasts belong to the division Ascomycota. A few yeasts, such as Candida albicans, can cause infection in humans. More than one thousand speci...