| oxidant | A molecule or atom that accepts electrons in an oxidation-reduction reaction. (09 Oct 1997) |
|---|---|
| oxidants | Oxidizing agents or electron-accepting molecules in chemical reactions in which electrons are transferred from one molecule to another (oxidation-reduction). In vivo, it appears that phagocyte-generated oxidants function as tumour promoters or cocarcinogens rather than as complete carcinogens perhaps because of the high levels of endogenous antioxidant defenses. It is also thought that oxidative damage in joints may trigger the autoimmune response that characterises the persistence of the rheumatoid disease process. (12 Dec 1998) |
| oxidants, photochemical | Compounds that accept electrons in an oxidation-reduction reaction. The reaction is induced by or accelerated by exposure to electromagnetic radiation in the spectrum of visible or ultraviolet light. (12 Dec 1998) |
| oxidase | Classically, one of a group of enzymes, now termed oxidoreductases (EC class 1), that bring about oxidation by the addition of oxygen to a metabolite or by the removal of hydrogen or of one or more electrons. Oxidase is now used for those cases in which O2 acts as an acceptor (of H or of electrons); those removing hydrogen are now termed dehydrogenases. For individual oxidases, see the specific names. Direct oxidase, originally, an oxidase catalyzing the transfer of O2 directly to other bodies; now termed oxygenase. Indirect oxidase, originally, an oxidase that acts by reducing a peroxide; now termed peroxidase. Terminal oxidase, the last protein in the electron transport, respiratory chain. In mammals this is cytochrome c oxidase. (05 Mar 2000) |
| oxidase reaction | The formation of indol blue when a blood smear containing myeloid leukocytes is treated with a mixture of alpha-naphthol and p-dimethylaniline sulfate; the myeloid leukocytes contain an oxidase that catalyses this reaction, the lymphoid leukocytes do not, in bacteriology, a reaction that depends on the presence of certain oxidases in some bacteria that catalyze the transport of electrons between electron donors in the bacteria and an oxidation reduction dye, such as tetramethyl-p-phenylenediamine; the dye is reduced to a blue or black colour. (05 Mar 2000) |
| oxidase test | A colon test for the presence of intracellular cytochrome oxidase based on the reaction with p-phenylenediamine; aids in the identification of Neisseria species and Pseudomonadaceae. (05 Mar 2000) |
| oxidasis | Oxidation by an oxidase. (05 Mar 2000) |
| oxidate | <chemistry> To oxidize. Origin: Cf. F. Oxyder. See Oxide. Source: Websters Dictionary (01 Mar 1998) |
| oxidation | <biochemistry> The process whereby fatty acids are degraded in steps, losing 2 carbons as (acetyl) CoA. Involves CoA ester formation, desaturation, hydroxylation and oxidation before each cleavage. (18 Nov 1997) |
| oxidation number | The number of electrons necessary to restore an atom in a combined state to its elemental form. (09 Oct 1997) |
| oxidation pond | A pond that contains partially treated wastewater which is then left to allow the growth of algae and bacteria which decompose therest of the waste. (09 Oct 1997) |
| oxidation-fermentation test | <investigation> A test to to determine whether a given bacterial strain has an oxidative or fermentativetype of metabolism by seeing what it doesto a carbohydrate substrate. (09 Oct 1997) |
| oxidation-reduction | A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs. (12 Dec 1998) |
| oxidation-reduction electrode | An electrode capable of measuring oxidation-reduction potential. See: quinhydrone electrode. Synonym: redox electrode. (05 Mar 2000) |
| oxidation-reduction indicator | A substance that undergoes a definite colour change at a specific oxidation potential. Synonym: redox indicator. (05 Mar 2000) |