Nucleosides nucleotide diphosphate 6-deoxy

Nucleosides, Nucleotides, Derivatives, and Related Compounds. — 5-Dimethyl-aminouridine, 5-methylaminomethyl-2-thiouridine, 2, 3 -O-isopropylidene-5-methylaminomethyl-2-thiouridine, 2 -deoxy-5-isopropyluridine, 5-amino-2, 5 -dideoxy-5-iodouridine, 5-nitro-l-( 3-D-ribofuranosyluronic acid)uracil, uridine 3 -phosphate, and uridine 5-diphosphate dipotassium salt. ... 

In view of the difficulty of hydrolyzing the pyrimidine nucleosidic linkages, ribonucleic acids have been hydrolyzed to a mixture of purine bases and pyrimidine nucleotides which is then separated by paper chromatography.132, 163 164 This method has been employed extensively for the analysis of ribonucleic acids, and gives reproducible results,166 but it has not been used to any great extent for deoxyribonucleic acids, probably because, under these conditions of hydrolysis, they yield some pyrimidine deoxy-ribonucleoside diphosphates.166... 

S Additional information <5, 7, 11, 25> (<5,7,11 > in the absence of nucleoside diphosphates the enzyme undergoes Mg -dependent stoichiometric autophosphorylation using ATP, GTP or y-thiotriphosphate as phosphate donor, 2 mol phosphate per mol enzyme [12] <25> autophosphorylation and phosphorylation of histone Hl [19] <31> strong preference for d-enantiomers of antiviral nucleotide analogs like ddATP, ddCTP, 3 -deoxy-3 -thymidine, 2 ,3 -didehydro-2 ,3 -dideoxythymidine [50]) [12, 19, 50]... 

The key intermediates in the biosynthesis of 6-deoxy sugars are the nucleoside 6-deoxyhexosyl-4-ulose diphosphates (7), formed through enzymic reactions catalyzed by NDP-sugar 4,6-dehydratases (EC 4.2.1.45-47) from primary glycosyl nucleotides. These reactions were observed... 

Thus, uridine-cytidine kinase converts uridine and cytidine to UMP and CMP, respectively thymidine kinase converts thymidine to dTMP and adenosine kinase converts adenosine to AMP. Specific kinases convert monophospho-nucleotides to dinucleotides using ATP as a phosphate donor. The conversion of diphosphonucleotides to triphosphonucleotides is carried out by a nonspecific nucleoside diphosphate kinase. This includes both the ribo- and deoxy-ribonucleotides. Cytosine and its nucleoside and nucleotide transformations are often associated with the metabolism of uracil and its nucleosides and nucleotides. Note that UTP can give rise to CTP (Figure 10.9), and also that, in the presence of cytidine deaminase, cytidine can be converted to uridine. 

In a study related to the mechanism of inactivation of ribonucleotide diphosphate reductase (RDPR) by 2 -deoxy-2 -substituted nucleotide analogues, it was found that treatment of nucleosides of type 57 (B=Ura, Ade, X=I, Br, Cl, SMe, N3) with tributylstannane and AIBN gave the d4 products 58, whilst with X=F, OMs or OTs, the 3 -deoxysystem 59 was the product. The results pointed to the loss of radicals rather than anions from C-2 during mechanism-based inactivation of RDPR, and the authors suggest some modifications to Stubbe s mechanistic proposals. ... 

Generally, UV absorption spectra can be utilized to determine the family to which an unknown base, nucleoside, or nucleotide belongs. Indeed, the chro-mophore of the nucleosides or nucleotides is typical of the purine or pyrimidine structvu-e, with different maximum absorption wavelengths in the adenosine, guanosine, cytosine, or thymidine series. For example, it is possible to differentiate readily the UV absorption spectra of guanosine (G), G-monophosphate (GMP), deoxy GMP (dGMP), G-diphosphate (GDP), and G-triphosphate (GTP), from those of adenosine (A), AMP, dAMP, ADR, and ATP. 

Nucleosidediphosphatase [Nucleosidediphosphate phosphohydrolase] (3.6.1.6) is produced and catalyzes the reaction A nucleoside diphosphate + H2O = a nucleotide + orthophosphate. [Acts on IDP, GDP, UDP and also on D-ribose 5-diphosphate.] Nucleotide pyrophosphatase [Dinucleotide nucleotidohydrolase] (3.6.1.9) is produced and catalyzes the reaction A dinucleotide + H2O = 2 mononucleotides. [Substrates include NAD" " NADP ", FAD, CoA and also ATP and ADP.] Deoxycytidinetriphosphatase [dCTP nucleotidohydrolase, Deoxy-CTPase, dCTPase] (3.6.1.12) is produced and catalyzes the reaction dCTP + H2O = dCMP + pyrophosphate. [Also hydrolyses dCDP to dCMP and orthophosphate]... 

Nucleotides are named as the 3 - or 5 -monophosphate esters of a nucleoside, as shown above. These names are frequently abbreviated as in Table 18.1. In these abbreviations, letter d stands for 2-deoxy-D-ribose, the next letter refers to the heterocyclic base, and MP stands for monophosphate. (Later we will see that some nucleotides are diphosphates, abbreviated DP, or triphosphates, TP.) Unless otherwise stated, the abbreviations usually refer to the 5 -phosphates. 

Starting from sucrose, one-pot reactions are suitable to work as regeneration cycles for nucleotide sugars as demonstrated for UDP-Glc, UDP-Gal, and dTDP-deoxy-sugars [98-103] (Scheme 6.4). Sucrose synthase (SuSy), known for the reverse reaction of a GT, is used in combination with different enzyme module systems. Nucleoside diphosphate (NDP) from GT modules are substrates of SuSy catalyzed synthesis of activated glucose (UDP-Glc, dTDP-Glc) which enter enzyme modules to generate the donor substrates of GTs. 

The base plus the sugar group (without the phosphate group) is called a nucleoside. Nucleosides are named from the bases. For example, the nucleoside composed of adenine with jS-D-ribose is called adenosine. The nucleoside composed of adenine with 2-deoxy-j8-D-ribose is called deoxyadenosine. A nucleotide is named by adding monophosphate (or diphosphate or triphosphate) after the nucleoside name. A number with a prime indicates the position of the phosphate group on the ribose ring. Thus, adenosine-5 -monophosphate is a nucleotide composed of adenine, jS-D-ribose, and a phosphate group at the 5 position of jS-D-ribose. 

The number of bound phosphates can vary in a nucleotide. When phosphate is absent, the molecule is referred to as a nucleoside or a deoxynucleoside, depending on the hydroxylation-state of the sugar. Up to three phosphate groups can be present. When one or more phosphates are present, the compound is commonly referred to by the base present, how many phosphates are present, and whether the deoxy-form of the sugar is used. For example, when the base adenine is present and there are two phosphates, the corresponding deoxyribonucleotide and ribonucleotide are typically referred to by the abbreviations, dADP and ADR The former and latter abbreviations indicate deoxy-adenine diphosphate and... 

The purine (Pu or R for short) and pyrimidine (Py or Y for short) bases, are connected by a N-glycosidic linkage to the C-T of the pentose sugar, either a ribose in RNA or a 2 -deoxyribose in DNA. The base-(2 -deoxy)ribose unit is called a nucleoside (ribonucleoside or 2 -deoxyribonucleoside). When a nucleoside is phosphorylated either at the 3 -OH or 5 -OH, it is called 3 -nucleotide (Np) or S -nucleotide (pN), respectively. The number of phosphate groups, for example, at the 5 -OH of adenosine, determines whether the nucleotides are designated as adenosine 5 -wo ophosphate (AMP), adenosine 5 -diphosphate (ADP), and... 

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