- phenylketonuria) and galactosemia, an error in the handling (metabolism) of the sugar galactose.
* * *A protein that acts as a catalyst to induce chemical changes in other substances, itself remaining apparently unchanged by the process. Enzymes, with the exception of those discovered long ago ( e.g., pepsin, emulsin), are generally named by adding -ase to the name of the substrate on which the e. acts ( e.g., glucosidase), the substance activated ( e.g., hydrogenase), and/or the type of reaction ( e.g., oxidoreductase, transferase, hydrolase, lyase, isomerase, ligase or synthetase—these being the six main groups in the E. Nomenclature Recommendations of the International Union of Biochemistry). For individual enzymes not listed below, see the specific name. SYN: organic catalyst (1). [G. + L. en, in + zyme, leaven]- adaptive e. SYN: induced e..- allosteric e. an e. that exhibits the property of allosterism.- amino acid activating e. SYN: aminoacyl-tRNA synthetases.- angiotensin-converting e. (ACE) SYN: peptidyl dipeptidase A.- antitumor e. an e. that stimulates the degradation of a particular metabolite that cannot be synthesized by tumor cells, inhibits the synthesis of a metabolite needed by tumor cells, or inhibits tumor-specific DNA utilization; E.G., asparaginase.- branching e. SYN: 1,4-α-d-glucan-branching e..- β-carotene-cleavage e. SYN: β-carotene 15,15′-dioxygenase.- citrate-cleavage e. SYN: ATP citrate (pro-3S)-lyase.- constitutive e. an e. that is constantly produced by the cell, regardless of the growth conditions. Cf.:induced e..- cooperative e. an e. that exhibits the property of cooperativity.- D e. SYN: 4-α-d-glucanotransferase.- deamidizing enzymes SYN: amidohydrolases.- deaminating enzymes SYN: deaminases.- debranching enzymes enzymes that bring about destruction of branches in glycogen; formerly considered to be one e., now known to be a mixture of transferases (4-α-d-glucanotransferase) and hydrolases (amylo-1,6-glucosidase). SYN: debranching factors.- digestive enzymes 1. enzymes that are utilized in the digestive system; 2. enzymes that are hydrolases of macromolecules ( E.G., amylases, proteinases).- disproportionating e. SYN: 4-α-d-glucanotransferase.- extracellular e. an e. performing its functions outside a cell; e.g., the various digestive enzymes. SYN: exoenzyme.- heat-stable e. SYN: thermostable e..- hydrolyzing enzymes SYN: hydrolases.- immobilized e. an e. that has been bound, usually covalently, to an insoluble organic or inorganic matrix or has been encapsulated.- induced e., inducible e. 1. an e. that can be detected in a growing culture of a microorganism, after the addition of a particular substance (inducer) to the culture medium, but was not detectable prior to the addition and can act on the inducer. A prototype is the β-galactosidase of Escherichia coli, synthesized upon the addition of various galactosides, whether or not these are good substrates. Cf.:constitutive e.. 2. any e. that has its rate of biosynthesis increased due to the presence of the substrate or some other molecular entity. SYN: adaptive e..- intracellular e. an e. that performs its functions within the cell that produces it; most enzymes are intracellular enzymes. SYN: endoenzyme (1).- methionine-activating e. SYN: methionine adenosyltransferase.- new yellow e. a former name for the d-amino-acid oxidase found in yeast, a flavoenzyme; so-called to distinguish it from Warburg old yellow e.. Cf.:amino acid oxidases.- P e. SYN: phosphorylase.- photoreactivating e. (PR e.) SYN: deoxyribodipyrimidine photolyase.- PR e. abbreviation for phosphorylase-rupturing e.; photoreactivating e..- Q e. 1,4-α-glucan branching e. in plants.- R e. SYN: α-dextrin endo-1,6-α-glucosidase.- reducing e. SYN: reductase.- repressible e. an e. that is produced continuously unless production is repressed by excess of an inhibitor (corepressor). SEE ALSO: inactive repressor.- respiratory e. a tissue e. that is part of an oxidation-reduction system accomplishing the conversion of substrates to CO2 and H2O and the transfer of the electrons removed to O2.- RNA e. SYN: ribozyme.- splitting enzymes enzymes that, like aldolases, catalyze the conversion of a molecule into two smaller molecules without the addition or subtraction of any atoms.- T e. 1,4-α-d-glucan 6-α-d-glucosyltransferase.- terminal addition e. SYN: DNA nucleotidylexotransferase.- thermostable e. an e. that is not readily subject to destruction or alteration by heat. SYN: heat-stable e..- transferring enzymes SYN: transferases.
* * *en·zyme 'en-.zīm n any of numerous complex proteins that are produced by living cells and catalyze specific biochemical reactions at body temperatures
* * *n.a protein that, in small amounts, speeds up the rate of a biological reaction without itself being used up in the reaction (i.e. it acts as a catalyst). An enzyme acts by binding with the substance involved in the reaction (the substrate) and converting it into another substance (the product of the reaction). An enzyme is relatively specific in the type of reaction it catalyses; hence there are many different enzymes for the various biochemical reactions. Each enzyme requires certain conditions for optimum activity, particularly correct temperature and pH, the presence of coenzyme, and the absence of specific inhibitors. Enzymes are unstable and are easily inactivated by heat or certain chemicals. They are produced within living cells and may act either within the cell (as in cellular respiration) or outside it (as in digestion). The names of enzymes usually end in '-ase'; enzymes are named according to the substrate upon which they act (as in lactase), or the type of reaction they catalyse (as in hydrolase).Enzymes are essential for the normal functioning and development of the body. Failure in the production or activity of a single enzyme may result in metabolic disorders; such disorders are often inherited and some have serious effects.• enzymatic adj.
* * *en·zyme (enґzīm) [en- + Gr. zymē leaven] a protein molecule that catalyzes chemical reactions of other substances without itself being destroyed or altered upon completion of the reactions. Symbol E. Enzymes are classified according to the recommendations of the Nomenclature Committee of the International Union of Biochemistry. Each enzyme is assigned a recommended name and an Enzyme Commission (EC) number. They are divided into six main groups: oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases. For individual enzymes, see under the specific name, e.g., glucose-6-phosphate dehydrogenase.
Medical dictionary. 2011.
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Enzyme — [zu griechisch en »in« und zýmē »Sauerteig«], Singular Enzym das, s, Biokatalysatoren, veraltete Bezeichnung: Fermẹnte, in allen lebenden Organismen vorkommende, intrazellulär gebildete, hochmolekulare Eiweißstoffe (Proteine), die chemische… … Universal-Lexikon
enzyme — [ ɑ̃zim ] n. f. ACAD. ou m. • 1878; gr. en « dans » et zumê « levain » ♦ Biochim. Substance protéique qui catalyse, accélère une réaction biochimique. ⇒ apoenzyme, coenzyme; vx diastase, ferment, zymase. Il existe un grand nombre d enzymes… … Encyclopédie Universelle
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enzyme — en zyme ([e^]n z[imac]m), n. [Pref. en (Gr. en in) + Gr. zy mh leaven.] (Physiol. Chem.) A protein produced by a living organism, capable of catalyzing a chemical reaction. Almost all processes in living organisms require some form of enzyme to… … The Collaborative International Dictionary of English
Enzyme — (griech.), eiweißartige Körper, die fermentartig wirken, in Pflanzen und Tieren weit verbreitet sind und in deren Lebensprozeß eine große Rolle spielen. Über ihre Zusammensetzung ist nichts Sicheres bekannt, über gemeinsame Eigenschaften läßt… … Meyers Großes Konversations-Lexikon
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enzyme — 1881, as a biochemical term, from Ger. Enzym, coined 1878 by German physiologist Wilhelm Kühne (1837 1900), from Modern Gk. enzymos leavened, from en in (see EN (Cf. en ) (2)) + zyme leaven (see ZYMURGY (Cf. zymurgy)) … Etymology dictionary
enzyme — ► NOUN ▪ a substance produced by a living organism and acting as a catalyst to promote a specific biochemical reaction. DERIVATIVES enzymatic adjective enzymic adjective. ORIGIN from modern Greek enzumos leavened … English terms dictionary
enzyme — [en′zīm΄] n. [Ger enzym < LGr enzymos, leavened < Gr en , in + zymē, leaven (see ZYME)] any of various proteins, formed in plant and animal cells or made synthetically, that act as organic catalysts in initiating or speeding up specific… … English World dictionary
Enzyme — Biocatalyst redirects here. For the use of natural catalysts in organic chemistry, see Biocatalysis. Human glyoxalase I. Two zinc ions that are needed for the enzyme to catalyze its reaction are shown as purp … Wikipedia
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