| 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) |
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| phosphorylases | 1. General term for enzymes transferring an inorganic phosphate group to some organic acceptor, hence belonging to the transferases. 2. Specifically, enzymes that release a single glucosyl residue from a polyglucose as d-glucose 1-phosphate, the phosphate coming from inorganic orthophosphate; e.g., phosphophorylase, sucrose phosphorylases, cellobiose phosphorylases. (05 Mar 2000) |
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| cap II RNA(nucleoside-2'-)methyltransferase | <enzyme> Converts cap i-terminated mRNA to cap II-terminated mRNA Registry number: EC 2.1.1.- Synonym: cap II methylase (26 Jun 1999) |
| cap I RNA (nucleoside-2'-)methyltransferase | <enzyme> Converts cap 0-terminated mRNA to cap i-terminated mRNA Registry number: EC 2.1.1.- Synonym: cap I methylase (26 Jun 1999) |
| 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) |
| purine-nucleoside phosphorylase | <enzyme> An enzyme that catalyses the reaction between a purine nucleoside and orthophosphate to form a free purine plus ribose-5-phosphate. Chemical name: Purine-nucleoside:orthophosphate ribosyltransferase Registry number: EC 2.4.2.1 (12 Dec 1998) |
| pyrimidine-nucleoside phosphorylase | <enzyme> Consider uridine phosphorylase and thymidine phosphorylase Registry number: EC 2.4.2.2 Synonym: pyrimidine nucleoside phosphorylase (26 Jun 1999) |
| 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) |