| mRNA (nucleoside-O(2'))-methyltransferase | <enzyme> Catalyses the reaction of s-adenosyl-l-methionine and m(7)g(5')pppr-RNA to yield s-adenosyl-l-homocysteine and m(7)g(5')ppprm-RNA; mRNA containing an o(2')-methylpurine cap Registry number: EC 2.1.1.57 (26 Jun 1999) |
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| pyrophosphate-nucleoside kinase | <enzyme> From acholeplasma laidlawii; phosphorylates adenosine, inosine, and guanosine to the corresponding mononucleotides Registry number: EC 2.7.1.- Synonym: ppi dependent nucleoside kinase (26 Jun 1999) |
| nucleoside | <biochemistry> Purine or pyrimidine base linked glycosidically to ribose or deoxyribose, but lacking the phosphate residues that would make it a nucleotide. Ribonucleosides are adenosine, guanosine, cytidine and uridine. Deoxyribosides are deoxyadenosine, deoxyguanosine, deoxycytidine and deoxythymidine (the latter is almost universally referred to as thymidine). (18 Nov 1997) |
| nucleoside analogue | A synthetic molecule that resembles a naturally occuring nucleoside, but that lacks a bond site needed to link it to an adjacent nucleotide. (09 Oct 1997) |
| nucleoside bisphosphate | A nucleoside that carries two independent (i.e., not linked to each other) phosphoric residues. Compare: nucleoside diphosphate. (05 Mar 2000) |
| nucleoside deaminases | <enzyme> Catalyze the hydrolysis of nucleosides with the elimination of ammonia. Registry number: EC 3.5.4 (12 Dec 1998) |
| nucleoside diphosphate | The pyrophosphoric ester of a nucleoside, i.e., a nucleoside in which the H of one of the ribose hydroxyls (usually the 5') is replaced by a pyrophosphoric (diphosphoric) radical; e.g., adenosine 5'-diphosphate. Compare: nucleoside bisphosphate. (05 Mar 2000) |
| nucleoside-diphosphate kinase | <enzyme> A phosphotransferase enzyme that is found in mitochondria and in the soluble cytoplasm of cells. It catalyses reversible reactions of a nucleoside triphosphate, e.g., ATP, with a nucleoside diphosphate, e.g., UDP, to form ADP and UTP. Many nucleoside diphosphates can act as acceptor, while many ribonucleoside triphosphates and deoxyribonucleoside triphosphates can act as a donor. Chemical name: ATP:nucleoside-diphosphate phosphotransferase Registry number: EC 2.7.4.6 (12 Dec 1998) |
| nucleoside-diphosphate sugars | Nucleoside diphosphates linked through the 5'-diphosphoric group with simple or complex carbohydrates; e.g., GDP-mannose, UDP-glucose (UDPG), dTDP-glucosamine. (05 Mar 2000) |
| nucleoside-diphosphosugar NAD+ 2-hexosyloxidoreductase | <enzyme> Oxidises udp-galactose to udp-2-ketogalactose Registry number: EC 1.1.1.- (26 Jun 1999) |
| nucleoside-diphosphosugar pyrophosphatase | <enzyme> Catalyses the conversion of xdp-sugar to xmp and sugar 1-phosphate Registry number: EC 3.6.1.- Synonym: ndp-sugar pyrophosphatase, nucleotide-sugar pyrophosphatase (26 Jun 1999) |
| nucleoside-monophosphate | A nucleotide, e.g., AMP. (05 Mar 2000) |
| nucleoside-phosphate kinase | <enzyme> An enzyme that catalyses reversible reactions of a nucleoside triphosphate, e.g., ATP, with a nucleoside monophosphate, e.g., ump, to form ADP and udp. Many nucleoside monophosphates can act as acceptor while many ribo- and deoxyribonucleoside triphosphates can act as donor. Chemical name: ATP:nucleoside-phosphate phosphotransferase Registry number: EC 2.7.4.4 (12 Dec 1998) |
| nucleoside phosphorylases | Enzymes that catalyze the phosphorolysis of a nucleoside, forming the free purine or pyrimidine plus ribose (or deoxyribose 1-phosphate); e.g., purine-nucleoside phosphorylases. (05 Mar 2000) |
| nucleoside q | <chemical> (1s-(1 alpha,4 beta,5 beta))-2-amino-5-(((4,5-dihydroxy-2-cyclopenten-1-yl)amino)methyl)-1,7-dihydro-7-beta-d-ribofuranosyl-4h-pyrrolo(2,3-d)pyrimidin-4-one. A modified nucleoside which is present in the first position of the anticodon of trna-tyrosine, trna-histidine, trna-asparagine and trna-aspartic acid of many organisms. It is believed to play a role in the regulatory function of trna. Nucleoside q can be further modified to nucleoside q*, which has a mannose or galactose moiety linked to position 4 of its cyclopentenediol moiety. Chemical name: 4H-Pyrrolo(2,3-d)pyrimidin-4-one, 2-amino-5-(((4,5-dihydroxy-2-cyclopenten-1-yl)amino)methyl)-1,7-dihydro-7-beta-D-ribofuranosyl-, (1S-(1alpha,4beta,5beta))- (12 Dec 1998) |