| xanthine oxidase | <enzyme> Dehydrogenases involved in conversion of hypoxanthine to xanthine and xanthine to uric acid, as the final catabolism of purines. Deficient in the human disease xanthinuria. (18 Nov 1997) |
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| methyl xanthine | <chemical, drug> Naturally occurring purine alkaloids such as theobromine, theophylline and caffeine (trimethyl xanthine). They inhibit cAMP phosphodiesterase and thus cause an increase in the intracellular cAMP concentration. (18 Nov 1997) |
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| xanthine | <biochemistry> A purine, the starting point for purine degradation. Its methylated derivatives (theophylline, theobromine, caffeine) are potent cAMP phosphodiesterase inhibitors. (18 Nov 1997) |
| xanthine alkaloids | Alkaloids, which contain xanthine as their nitrogenous base. (12 Dec 1998) |
| xanthine bronchodilator | <pharmacology> A group of medications that work by a common mechanism to effect bronchodilation (open up air passages) in the lungs. Used in the treatment of asthma and related conditions. Examples include: theophylline, aminophylline and dyphylline. (27 Sep 1997) |
| xanthine dehydrogenase | <enzyme> An enzyme that catalyses the oxidation of xanthine in the presence of NAD+ to form urate and NADH. It acts also on a variety of other purines and aldehydes. Chemical name: Xanthine:NAD+ oxidoreductase Registry number: EC 1.1.1.204 (12 Dec 1998) |
| xanthine nucleotide | The monophosphoric ester of xanthosine. An intermediate in GMP biosynthesis. Synonym: xanthidylic acid, xanthine nucleotide, xanthylic acid. (05 Mar 2000) |
| xanthine ribonucleoside | 9-beta-d-ribosylxanthine;the deamination product of guanosine (O replacing -NH2). Synonym: xanthine ribonucleoside. Abbreviation: Xao (05 Mar 2000) |
| hypoxanthine-guanine-xanthine phosphoribosyltransferase | <enzyme> From tritrichomonas foetus; in contrast to EC 2.4.2.8, this enzyme also uses xanthine as substrate; mw 24 kD Registry number: EC 2.4.2.- Synonym: hgxprtase (26 Jun 1999) |
| desulfo xanthine dehydrogenase | <enzyme> Naturally occuring inactive form of xanthine dehydrogenase Registry number: EC 1.1.1.- (26 Jun 1999) |
| acetaldehyde oxidase | <enzyme> Acetaldehyde is converted to acetate Registry number: EC 1.2.- (26 Jun 1999) |
| acyl-CoA oxidase | <enzyme> Catalyses stoichiometric conversion of palmitoyl-CoA and o2 into 2-hexadecenoyl-CoA and h2o2; oxidises acyl-CoA's with carbon chain lengths of 4 to 20; most active toward lauroyl-CoA, but not acetyl- or succinyl-CoA Registry number: EC 1.3.3.6 Synonym: fatty acyl CoA oxidase, fatty acyl-coenzyme a oxidase, fatty acid acyl-CoA oxidase, acox, pox1 gene product (26 Jun 1999) |
| adrenaline oxidase | amine oxidase (flavin-containing) |
| aldehyde oxidase | <enzyme> Broad substrate specificity Registry number: EC 1.2.3.1 Synonym: n1-methylnicotinamide oxidase I, n-nitrosoreductase (26 Jun 1999) |
| alternative oxidase | <enzyme> The terminal oxidase in alternative pathway respiration, as seen in plants like sauromatum guttatum (voodoo lily); amino acid sequence for tobacco alternative oxidase (aox1) in first source Registry number: EC 1.- Synonym: aox1 gene product, aox2 gene product, aox3 gene product (26 Jun 1999) |
| alternative oxidase pathway | Pathway of mitochondrial electron transport in higher plants, particularly in fruits and seeds, that does not involve cytochrome oxidase and thus is resistant to cyanide. (18 Nov 1997) |