| TAB vaccine | A suspension of killed typhoid and paratyphoid A and B bacilli. See: typhoid vaccine. Synonym: TAB vaccine. (05 Mar 2000) |
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| alpha-tocopherol | <chemical> A light yellow, viscous, odourless, oily liquid that deteriorates on exposure to light, is obtained from wheat germ oil or by synthesis, biologically exhibits the most vitamin E activity of the alpha-tocopherol's, and is an antioxidant retarding rancidity by interfering with the autoxidation of fats. Prepared from natural phytol, it is called 2-ambo-alpha-tocopherol; from synthetic phytol, all-rac-alpha-tocopherol or synt-alpha-tocopherol; also available are d-alpha-tocopheryl acetate, dl-alpha-tocopheryl acetate, d-alpha-tocopheryl acid succinate, and d-alpha-tocopheryl acetate concentrate. One of several forms of vitamin E. Chemical name: 2,5,7,8-tetramethyl-2-(4',8',12'-trimeth yltridecyl)-6-chromanol; 5,7,8-trimethyltocol Synonym: vitamin E. (14 Aug 2000) |
| beta-tocopherol | 5,8-Dimethyltocol;a lower homolog of alpha-tocopherol, that contains one less methyl group in the aromatic nucleus and is less active biologically; accompanies alpha-T and gamma-beta-tocopherol (05 Mar 2000) |
| gamma-tocopherol | 7,8-Dimethyltocol;a form biologically less active than alpha-gamma-tocopherol (05 Mar 2000) |
| gamma-tocopherol methyltransferase | <enzyme> Forms alpha-tocopherol; enzyme nomenclature name of tocopherol o-methyltransferase is incorrect, since there are no -och3 groups in the product Registry number: EC 2.1.1.95 Synonym: gtc methyltransferase (26 Jun 1999) |
| S-adenosylmethionine-tocopherol methyltransferase | <enzyme> Catalyses methylation of positions 7 or 8 of the tocol ring, forming gamma-tocopherol (7,8-dimethyltocol); see also EC 2.1.1.95, which converts gamma-tocopherol to alpha-tocopherol (5,7,8-trimethyltocol) Registry number: EC 2.1.1.- Synonym: sam-tocopherol methyltransferase (26 Jun 1999) |
| tocopherol | 1. Name given to vitamin E by its discoverer, but now a generic term for vitamin E and compounds chemically related to it, with or without biological activity; similar in chemical structure and properties to vitamins K and coenzyme Q. 2. A methylated tocol or methylated tocotrienol. Mixed tocopherols concentrate, a source of vitamin E, obtained by vacuum distillation of edible vegetable oils or their by-products. (05 Mar 2000) |
| tocopherol cyclase | <enzyme> Catalyses cyclization of phytyl-hydroquinone to gamma-tocopherol; isolated from the blue-green alga anabaena variabilis Registry number: EC 5.4.99.- (26 Jun 1999) |
| acetate | <biochemistry> A salt or ester of acetic acid, specifically, a synthetic textile fibre made from partially hydrolysed cellulose acetate, or a plastic-like film made from cellulose triacetate. The terminal hydrogen atom in the molecule is replaced by a metal, for instance copper acetate, or where substitution is by a radical, for instance ethyl acetate. (04 Jul 1999) |
| acetate-CoA ligase | <enzyme> An enzyme that catalyses the formation of CoA derivatives from ATP, acetate, and CoA to form AMP, pyrophosphate, and acetyl CoA. It acts also on propionates and acrylates. Chemical name: Acetate:CoA ligase (AMP-forming) Registry number: EC 6.2.1.1 (12 Dec 1998) |
| acetate kinase | <enzyme> An enzyme that catalyses reversibly the phosphorylation of acetate in the presence of a divalent cation and ATP with the formation of acetylphosphate and ADP. It is important in the glycolysis process. Chemical name: ATP:acetate phosphotransferase Registry number: EC 2.7.2.1 (12 Dec 1998) |
| acetate replacement factor | <biochemistry> 1,2 dithiolane 3 valeric acid. Regarded as a coenzyme in the oxoglutarate dehydrogenase complex of the citric acid cycle. Involved generally in oxidative decarboxylations of _ keto acids. A growth factor for some organisms. (18 Nov 1997) |
| acetate-succinate CoA-transferase | <enzyme> Tritichomonas and trichomonas enzyme converts acetyl-CoA and succinate to acetate and succinyl-CoA Registry number: EC 2.8.3.- Synonym: acetate-succinate coenzyme a-transferase (26 Jun 1999) |
| acetate thiokinase | 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) |
| active acetate | <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) |