| Xan | xanthine |
|---|---|
| XDH | xanthine dehydrogenase |
| XDP | xanthine diphosphate; xeroderma pigmentosum |
| XMP | xanthine monophosphate |
| XO | presence of only one sex chromosome; xanthine oxidase |
| X-XO | Xanthine-xanthine oxidase |
|---|---|
| MIX | 1-Methyl-3-isobutyl-xanthine |
| 1-MX | 1-methyl xanthine |
| 1X | 1-methyl xanthine |
| [(3)H]-DPCPX | 3)H]-1, 3-dipropyl-,8-cyclopentyl xanthine |
methyl group
| 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) |
|---|
| 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 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) |
| 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) |
| active methyl | A methyl group attached to a quaternary ammonium ion or a tertiary sulfonium ion that can take part in transmethylation reactions; e.g., methyl groups in choline and in S-adenosyl-l-methionine, which are thus methyl donors. (05 Mar 2000) |
| aklanonic acid methyl ester cyclase | <enzyme> Catalyses the formation of aklaviketone from aklanonic acid methyl ester; involved in daunomycin biosynthesis; see also daunorubicin-doxorubicin polyketide synthase Registry number: EC 5.- Synonym: aame cyclase, daud protein, daud gene product, dnrd protein, dnrd gene product (26 Jun 1999) |
| alpha-(4-O-methyl)-D-glucuronidase | <enzyme> Removes 4-o-methyl-glucopyranosyl uronic acid residues from the 2-position of fungal cell wall xylans Registry number: EC 3.2.1.- Synonym: 4-o-methyl-glucuronidase (26 Jun 1999) |
| alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid | <chemical> Alpha-amino-2,3-dihydro-5-methyl-3-oxo-4-isoxazolepropanoic acid. An ibotenic acid homolog and glutamate agonist. The compound is the defining agonist for the ampa subtype of glutamate receptors (receptors, ampa). It has been used as a radionuclide imaging agent but is more commonly used as an experimental tool in cell biological studies. Pharmacological action: excitatory amino acid agonists. Chemical name: 4-Isoxazolepropanoic acid, alpha-amino-2,3-dihydro-5-methyl-3-oxo- (12 Dec 1998) |
| alpha methyl dopa | <drug> An antihypertensive drug, preferred in pregnant patients. (18 Nov 1997) |
| angular methyl | A methyl group attached to carbon 10 (between rings A and B) or to carbon 13 (between rings C and D) of the steroid nucleus. (05 Mar 2000) |
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