| nucleorrhexis | Fragmentation of a cell nucleus. Origin: nucleo-+ G. Rhexis, rupture (05 Mar 2000) |
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| nucleosidase | <enzyme> Catalyses hydrolysis of n-ribosyl-purine into a purine and d-ribose Registry number: EC 3.2.2.1 Synonym: purine nucleoside hydrolase, guanosine hydrolase (26 Jun 1999) |
| nucleosidases | <enzyme> Registry number: EC 3.2.2. (12 Dec 1998) |
| 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 phosphorylase | <enzyme> From klebsiella sp.; acts on both purine and pyrimidine nucleosides and catalyses the production of araa from uridine arabinoside (arau) and adenine Registry number: EC 2.4.2.- (26 Jun 1999) |
| 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) |
| nucleoside triphosphate | A nucleoside in which the H of one of the ribose hydroxyls (usually the 5') is replaced by a triphosphoric group, -PO(OH)-O-PO(OH)-O-PO(OH)2; e.g., adenosine triphosphate. (05 Mar 2000) |
| nucleoside triphosphate-adenylate kinase | <enzyme> Other nucleoside triphosphates may replace GTP as substrate Registry number: EC 2.7.4.10 Synonym: GTP-AMP phosphotransferase, AMP-GTP phosphotransferase (26 Jun 1999) |
| 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) |
Synonyms :
Synonyms : Dinucleosomes, Polynucleosomes, Dinucleosome, Nucleosome, Polynucleosome
Synonyms :
Synonyms : Deaminases, Nucleotide
Synonyms : Fingerprint, Nucleotide, Mapping, Nucleotide, Mappings, Nucleotide, Nucleotide Fingerprint, Nucleotide Fingerprints, Nucleotide Mappings
| nucleotide |
A nucleoside with one or more phosphate groups linked to the 5?carbon of the pentose sugar. Ribose-containing nucleosides include ribonucleoside monophosphate (NMP), ribonucleoside diphosphate (NDP), and ribonucleoside triphosphate (NTP). When the nucleoside contains the sugar deoxyribose, the nucleotides are called deoxyribonucleoside mono-, di-, or tri-phosphates (dNMP, dNDP, or dNTP). A building block of DNA and RNA. ...
Ãâó: www.fao.org/docrep/003/X3910E/X3910E17.htm
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| nucleoside analogue |
A synthetic molecule that resembles a naturally occurring nucleoside, but that lacks the bond site needed to link it to an adjacent nucleotide. See nucleoside.
Ãâó: www.fao.org/docrep/003/X3910E/X3910E17.htm
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| nucleolar organizer |
(NO); nucleolar organizer region (NOR) A chromosomal segment containing genes that encode ribosomal RNA; located at the secondary constriction of some chromosomes.
Ãâó: www.fao.org/docrep/003/X3910E/X3910E17.htm
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| nucleolus |
(L. nucleolus, a small nucleus) An RNA-rich intranuclear organelle in the nucleus of eukaryotic cells, produced by a nucleolar organizer. It represents the storage place for ribosomes and ribosome precursors. The nucleolus consists primarily of ribosomal precursor RNA, ribosomal RNA, their associated proteins, and some, perhaps all, of the enzymatic equipment (RNA polymerase, RNA methylase, RNA cleavage enzymes) required for synthesis, conversion and assembly of ribosomes. ...
Ãâó: www.fao.org/docrep/003/X3910E/X3910E17.htm
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| nucleoplasm |
The non-staining or slightly chromophilic, liquid or semi-liquid, ground substance of the interphase nucleus and which fills the nuclear space around the chromosomes and the nucleoli. Little is known of the chemical composition of this ground substance, which is not easily defined. It may be called "karyoplasm" when it is gel-like, and "karyolymph" when it is a colloidal fluid, but generally the terms are synonymous.
Ãâó: www.fao.org/docrep/003/X3910E/X3910E17.htm
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