Enzyme

Enzyme

Enzymes ( /ˈɛnzaɪmz/) are large biological molecules responsible for the thousands of chemical interconversions that sustain life. They are highly selective catalysts, greatly accelerating both the rate and specificity of metabolic reactions, from the digestion of food to the synthesis of DNA. Most enzymes are proteins, although some catalytic RNA molecules have been identified. Enzymes adopt a specific three-dimensional structure, and may employ organic (e.g. biotin) and inorganic (e.g. magnesium ion) cofactors to assist in catalysis.

In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates sufficient for life. Since enzymes are selective for their substrates and speed up only a few reactions from among many possibilities, the set of enzymes made in a cell determines which metabolic pathways occur in that cell.

Like all catalysts, enzymes work by lowering the activation energy (Ea‡) for a reaction, thus dramatically increasing the rate of the reaction. As a result, products are formed faster and reactions reach their equilibrium state more rapidly. Most enzyme reaction rates are millions of times faster than those of comparable un-catalyzed reactions. As with all catalysts, enzymes are not consumed by the reactions they catalyze, nor do they alter the equilibrium of these reactions. However, enzymes do differ from most other catalysts in that they are highly specific for their substrates. Enzymes are known to catalyze about 4,000 biochemical reactions. A few RNA molecules called ribozymes also catalyze reactions, with an important example being some parts of the ribosome. Synthetic molecules called artificial enzymes also display enzyme-like catalysis.

Enzyme activity can be affected by other molecules. Inhibitors are molecules that decrease enzyme activity; activators are molecules that increase activity. Many drugs and poisons are enzyme inhibitors. Activity is also affected by temperature, pressure, chemical environment (e.g., pH), and the concentration of substrate. Some enzymes are used commercially, for example, in the synthesis of antibiotics. In addition, some household products use enzymes to speed up biochemical reactions (e.g., enzymes in biological washing powders break down protein or fat stains on clothes; enzymes in meat tenderizers break down proteins into smaller molecules, making the meat easier to chew).

Read more about EnzymeEtymology and History, Structures and Mechanisms, Thermodynamics, Kinetics, Inhibition, Biological Function, Control of Activity, Involvement in Disease, Naming Conventions, Industrial Applications

Other articles related to "enzyme, enzymes":

UDP-N-acetylglucosamine-lysosomal-enzyme N-acetylglucosaminephosphotransferase
... In enzymology, an UDP-N-acetylglucosamine-lysosomal-enzyme N-acetylglucosaminephosphotransferase (EC 2.7.8.17) is an enzyme that catalyzes the chemical reaction ... This enzyme belongs to the family of transferases, specifically those transferring phosphorus-containing groups transferases for other substituted phosphate ... The systematic name of this enzyme class is UDP-N-acetyl-D-glucosaminelysosomal-enzyme N-acetylglucosaminephosphotransferase ...
UGT1A4
... UDP-glucuronosyltransferase 1-4 is an enzyme that in humans is encoded by the UGT1A4 gene ... This gene encodes a UDP-glucuronosyltransferase, an enzyme of the glucuronidation pathway that transforms small lipophilic molecules, such as steroids, bilirubin, hormones, and drugs, into water-soluble ... This enzyme has some glucuronidase activity towards bilirubin, although it is more active on amines, steroids, and sapogenins ...
UGT1A3
... UDP-glucuronosyltransferase 1-3 is an enzyme that in humans is encoded by the UGT1A3 gene ... This gene encodes a UDP-glucuronosyltransferase, an enzyme of the glucuronidation pathway that transforms small lipophilic molecules, such as steroids ... Substrates of this enzyme include estrone, 2-hydroxyestrone, and metabolites of benzo alpha-pyrene ...
UBE1C
... activity • ligand-dependent nuclear receptor binding • NEDD8 activating enzyme activity • protein heterodimerization activity Cellular component • nucleus Biological ... Ubiquitination involves at least three classes of enzymes ubiquitin-activating enzymes, or E1s, ubiquitin-conjugating enzymes, or E2s, and ubiquitin-pro ... This gene encodes a member of the E1 ubiquitin-activating enzyme family ...
Enzyme - Industrial Applications
... Enzymes are used in the chemical industry and other industrial applications when extremely specific catalysts are required ... However, enzymes in general are limited in the number of reactions they have evolved to catalyze and also by their lack of stability in organic solvents and at high temperatures ... research and involves attempts to create new enzymes with novel properties, either through rational design or in vitro evolution ...