| tenth-value layer | <radiobiology> Thickness of a specified substance which, when introduced into the path of a given beam of radiation, reduces the absorbed dose index or dose-equivalent index to one-tenth. The magnitude of the tenth-value layer may be different for absorbed dose index and dose equivalent index. (16 Dec 1997) |
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| thiocyanogen value | The number of grams of thiocyanogen taken up by 100 g of fat; analogous to the iodine number, except that thiocyanogen will not add to all the double bonds in polyunsaturated fatty acids as will iodine. Synonym: thiocyanogen value. (05 Mar 2000) |
| threshold limit value | The maximum concentration of a chemical recommended by the American Conference of Government Industrial Hygienists for repeated exposure without adverse health effects on workers. (05 Mar 2000) |
| economic value of life | The evaluation of the monetary value of a life lost or a life saved. (12 Dec 1998) |
| law of initial value | The direction of response of a body function to any agent depends to a large degree on the initial level of that function. Synonym: law of initial value. (05 Mar 2000) |
| lower heating value | (LHV) The potential energy in a fuel if the water vapour from combustion of hydrogen is not condensed. (05 Dec 1998) |
| acetyl | <biochemistry, chemistry> This is the radical of acetic acid, it contains a carbonyl and a methyl group that is single-bonded to the carbon, an oxygen is single-bonded to the carbon, and the carbon has two other bonds to the rest of the molecule. (09 Oct 1997) |
| acetyl-activating enzyme | A ligase that catalyses the reaction of acetate and CoA and ATP to form AMP, pyrophosphate, and acetyl-CoA. A key step in the activation of acetate. Synonym: acetate thiokinase, acetate-CoA ligase, acetyl-activating enzyme, acetyl-CoA synthetase. (05 Mar 2000) |
| acetyl chloride | CH3COCl;a colourless liquid used as a reagent; also corrosive, causing severe burns because of hydrolysis to HCl. (05 Mar 2000) |
| acetyl-CoA | <enzyme> Condensation product of coenzyme A and acetic acid, symbolised as CoAS~COCH3; intermediate in transfer of two-carbon fragment, notably in its entrance into the tricarboxylic acid cycle and in fatty acid synthesis. This coenzyme plays a huge role in intermediary metabolism, in which cells synthesise, break down or use nutrient molecules for energy production, growth, etc. Acetyl-coenzyme A synthase is found in bacteria and plants and catalyses the reaction in which acetate enters metabolic pathways and forms acetyl-coenzyme A. Synonym: acetyl-coenzyme A, active acetate. (05 Mar 2000) |
| acetyl-CoA-1-alkyl-2-lyso-sn-glycero-3-phosphocholine acetyltransferase | <enzyme> Transfers acetate from acetyl CoA to the sn-2-position of 1-alkyl-2-lyso-glycerophosphocholine, forming the substrate for 1-alkylglycerophosphocholine acetyltransferase (EC 2.3.1.67) Registry number: EC 2.3.1.- Synonym: acopc acetyltransferase, 1-alkyl-2-lyso-sn-glycero-3-phosphocholine-acetyl CoA acetyltransferase, alkyllyso-gp-acetyl-CoA acetyltransferase, acetyl-coenzyme a-1-alkyl-2-lyso-sn-glycero-3-phosphocholine acetyltransferase (26 Jun 1999) |
| acetyl-CoA acetyltransferase | An acetyltransferase forming acetoacetyl-CoA from two molecules of acetyl-CoA, releasing one CoA. A key step in ketogenesis and sterol synthesis. Synonym: acetoacetyl-CoA thiolase, acetyl-CoA thiolase, thiolase. (05 Mar 2000) |
| acetyl-CoA acylase | <enzyme> An enzyme that catalyses reversibly the hydrolysis of acetyl-CoA to yield CoA and acetate. The enzyme is involved in the oxidation of fatty acids. Chemical name: Acetyl-CoA hydrolase Registry number: EC 3.1.2.1 (12 Dec 1998) |
| acetyl-CoA acyltransferase | <enzyme> An enzyme catalyzing the thioclastic cleavage by coenzyme A of beta-ketoacyl-CoA, forming an acyl-CoA with a carbon chain shorter by two atoms, the missing two atoms appearing as acetyl-CoA. A step in fatty acid degradation. See: acetyl-CoA acetyltransferase. Synonym: 3-ketoacyl-CoA thiolase, beta-ketothiolase. (05 Mar 2000) |
| acetyl-CoA:alpha-glucosaminide acetyltransferase | <enzyme> An enzyme involved in the synthesis of certain carbohydrate moieties on proteins. A deficiency of this enzyme leads to mucopolysaccharidosis type III C. (05 Mar 2000) |