| active | Characterised by action, not passive, not expectant. (18 Nov 1997) |
|---|---|
| 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) |
| active aldehyde | Any aldehyde derivative of thiamin pyrophosphate. (05 Mar 2000) |
| active anaphylaxis | Reaction following inoculation of antigen in a subject previously sensitised to the specific antigen, in contrast to passive anaphylaxis. (05 Mar 2000) |
| active biomass | <cell biology> The amount of a given culture that is actively growing. (06 May 1997) |
| active carbon dioxide | Activated carbon dioxide, a complex of N-carboxybiotin (biotin + CO2) and an enzyme; the form in which carbon dioxide is added to other molecules in carboxylations; e.g., to methylcrotonyl-CoA to form beta-methylglutaconyl in the catabolism of leucine, and to acetyl-CoA to form malonyl-CoA. See: acetyl-CoA carboxylase. (05 Mar 2000) |
| active caries | Microbial-induced lesions of teeth that are increasing in size. (05 Mar 2000) |
| active centre | The part of a macromolecule at which a substrate or ligand, upon binding, produces biological activity; for an enzyme, this is the catalytic centre, the site on an enzyme that catalyses the reaction. (05 Mar 2000) |
| active congestion | Congestion due to an increased flow of arterial blood to a part. (05 Mar 2000) |
| active electrode | A small electrode whose exciting effect is used to stimulate or record potentials from a localised area. Synonym: exciting electrode, localizing electrode, therapeutic electrode. (05 Mar 2000) |
| active formaldehyde | A hydroxymethyl derivative of tetrahydrofolate or thiamin pyrophosphate, N5,N10-methylenetetrahydrofo late. (05 Mar 2000) |
| active formyl | The formyl group taking part in transformylation reactions with a folic acid derivative in the role of carrier. (05 Mar 2000) |
| active immunity | <immunology> An organisms resistance to disease or infection, developed because the organisms immune system has produced antibodies after an infection or innoculation. (06 May 1997) |
| active immunization | The production of active immunity. (05 Mar 2000) |
| active inflammation | Any inflammation that has a fairly rapid onset, quickly becomes severe, usually manifested for only a few days, but may persist for several days or even a few weeks. Synonym: active inflammation. (05 Mar 2000) |