Pyrimidine ribonucleoside

Radulovacki, M., Virus, R. M., Rapoza, D. Crane, R. A. (1985). A comparison of the dose response effects of pyrimidine ribonucleosides and adenosine on sleep in rats. Psychopharmacology 87 (2), 136-40. 

Hydrolysis of ribonucleic acids by snake venom was found to yield inorganic phosphate, nucleosides, and pyrimidine ribonucleoside diphosphates.197 These diphosphates were shown by their behavior toward various enzymes to be mixtures of 2,5- and 3,5-diphosphates, and it therefore seems likely that they were formed through intermediate, cyclic phosphates. Thus, although this evidence confirms the existence of 2(or 3) — 5 linkages, it does not distinguish between the 2- and 3-positions. 

Ultraviolet (UV) spectroscopy does not tend to be the method of choice for structure determination, but a list of UV absorptions was given in the review by Knowles <1996CHEC-II(7)489>. Fluorescence properties and triplet yields of [l,2,3]triazolo[4,5-r/ pyridazines in various solvents have been reported <2002JPH83>. These heterocyclic systems were found to be photochemically very stable. In a recent paper, Wierzchowski et al. studied the fluorescence emission properties of 8-azaxanthine ([l,2,3]triazolo[4,5-r/ pyrimidine-5,7-dione) and its A -alkyl derivatives at various pH s <2006JPH276>. For the 8-azaxanthines, an important characteristic of emission spectra in aqueous solutions was the unusually large Stokes shift. Since 8-azaxanthine is a substrate for purine nucleoside phosphorylase II from Escherichia coli, the reaction is now monitored fluorimetrically. The fluorescence properties of [l,2,3]triazolo[4,5-r/ -pyrimidine ribonucleosides were earlier described by Seela et al. <2005HCA751>. 

Additional information <1> (<1>, the deletion mutants rDm-dNKAClO and rDm-dNKAC20 show the same substrate activity pattern as the recombinant wild-type enzyme. Relative phosphorylation of 2 -deoxycytidine and 2-chloro-2 -deoxyadenosine increases with increasing C-terminal truncation. The relative activities of rDm-dNKAClO and rDm-dNKAC20 with deoxyribonucleosides remains largely unchanged, whereas there is a substantial decrease in the phosphorylation of the purine ribonucleosides adenosine and guanosine, as well as of all dideoxyribonucleosides and 3 -azido-2 ,3 -dide-oxythymidine. The relative activities with the pyrimidine ribonucleosides and l-/l-D-arabinofuranosylcytosine and l-/i-D-arabinofuranosylthymine are not affected by the C-terminal deletions [4]) [4]... 

I. Hirao, K. Itoh, N. Sakairi, Y. Araki, and Y. Ishido, Bis(tributyltin) oxide—phenyl isocyanate system for regioselective (phenyl-carbamoyl)ation of purine and pyrimidine ribonucleosides, Carbohydr. Res., 109 (1982) 181-205. 

Determination of the ring structure of the pyrimidine ribonucleosides, uridine and cytidine, as being furanoid was accomplished by Levene and... 

The syn and anti conformations of pyrimidine ribonucleosides have an opposite sign for certain transitions (e.g., the B2u transition) (67B843 69JA831 71JA(93)1600 72JCP2736 72MI3). Such relations are empirical correlations, since the molecular structures are too complicated to allow theoretical calculations of the rotational strengths. A combination of DNMR, CD spectroscopy, and molecular mechanics calculations has been applied to derivatives of indole 77 and thiazoline-2-thione 78 substituted by chiral rotors (Scheme 58). In these molecules the rotor adopts one of the bisected... 

Roy SK, Tang J-y. Efficient large scale synthesis of 2 -0-aIkyl pyrimidine ribonucleosides. Org. Process Res. Dev. 2000 4 170-171. 

Differentiate purines, pyrimidines, ribonucleosides, deoxyribonucleosides, ribonucleotides, and deoxyribonudeotides. 

The 2 -deoxy-2 -methylene nucleoside 92 has been prepared using a Wittig reaction, and a number of other 4-amino-5-oxo-pyrido[2,3-d]pyrimidine ribonucleosides with chain branches at C-2, C-3 and C-4 were also reported. ... 

In experiments of this type with animal tissues, Rose and Schweigert (2) and Thomson et al. (S) showed that pyrimidine ribonucleosides were converted to DNA nucleotides without cleavage of the JNT-glycosidic bond. As well, Larsson and Neilands (4) performed a similar type of experiment in which P-phosphate and uniformly labeled C-cytidine were administered to rats with regenerating liver. Both substances were incorporated into the liver polynucleotides which, upon isolation, were degraded to their constituent nucleotides for analysis. Their data (Table 16-1) showed that the four nucleotides of RNA had similar specific activities with respect to P, indicating that the labeled phosphate readily equilibrated with the nucleoside phosphate pool during the experimental period. In this experiment, cytidylate derived from RNA and deoxycytidylate derived from DNA had the same P C ratio. This result indicated that both polynucleotide subunits, deoxycytidylate and cytidylate, were derived from a common precursor, evidently a ribonucleotide. 

The ability of nucleoside triphosphates, singly, or in combination, to effect changes in the catalytic properties of the reductase have been explored systematically by Reichard and his co-workers the complicated pattern of results is summarized in Table 16-11. These findings have been interpreted in terms of four states of activity for the reductase. In the presence of ATP, the reductase prefers as substrates pyrimidine nucleoside diphosphates. In the presence of dGTP, a purine-specific state is assumed and dTTP causes the enzyme to be in a condition in which both purine and pyrimidine ribonucleoside diphosphates are reduced. 

The effects of dATP are complex. Low concentrations of dATP stimulate reduction of pyrimidine ribonucleoside diphosphates, whereas at high concentrations, dATP becomes a potent, general inhibitor of nucleotide reduction it is also seen that low concentrations of dATP counteract the stimulatory effects of dTTP and dGTP. It has been concluded that dATP converts the enzyme into an inactive state. 

The promastigotes of donovani were incubated for 24 hours at a concentration of about 10 cells/ml in the presence of (4-3 S)TPP, (4- 5s)tppr, and (U-l C-ribose)TPPR. A radioactive metabolic product was identified which had a retention time and ultraviolet absorption spectrum identical to authentic 4-thio-pyrazolo(3,4-d)pyrimidine ribonucleoside-5 -phosphate (TPPR-MP). 

Table 193 gives a comparison of the separations of nucleobases and nucleosides on paper and on layers of cellulose, silica gel G and ECTEOLA-cellulose. The extensive agreement of the hJK/-values of the purine bases and purine nucleosides on the cellulose and ECTEOLA-ceUulose layers and on paper, is striking appreciably higher LB/-values were found on silica gel G. The various pyrimidines and pyrimidine-ribonucleosides have very nearly identical LB/-values on the three layers and on paper. A better separation of the purine and pyrimidine bases from the corresponding ribonucleosides is achived on cellulose and ECTEOLA cellulose layers than on sihca gel G. These three adsorbents are about equally useful for fractionating the nucleosides. 

TLC on cellulose and silica gel layers has been appLed to separate the fluorinated [30] and iodinated pyrimidines and pyrimidine ribonucleosides [23, 47] which are important in cancer therapy. Other domains in which TLC has been appLed with profit are analyses of products of organic synthesis [7, 42, 44] and of enzymatic reactions [38, 110]. 

Preparation of Nvcleosides. Levene and Jacobs 83c) treated ribonucleic acid with ammonia in an autoclave (175 ) and isolated the crystalline purine and pyrimidine ribonucleosides, adenosine and guanosine (9-iV -j8-D ribofuranosyladenine and -guanine) and cytidine and uridine (9-iV-i8-D-ribofuranosylcytosine and -uracil) respectively. Improvements in the chemical hydrolysis have been made through the use of magnesium oxide... 

Semi-empirical potential-energy calculations have been carried out on purine and pyrimidine ribonucleoside 2, 3 -cyclic phosphates and the 5 -phosphates. ... 

Since the pyrimidines of RNA as well as those of DNA were labeled after administration of isotopic cytidine, it was suggested that there had lieen a conversion of a pyrimidine ribonucleoside to a pyrimidine deoxy-ribonucleoside (317). It was reasoned that cytidine could not have lieen split to cytosine and then reincorporated into deoxycytidine, because cytosine was not utilized for the synthesis of nucleic acid p3uimidines (303). The suggested conversion may possibly have occurred at the nu cleotide level, thus, cytidylic acid may have been the intermediate in the transformation of RNA to DNA pyrimidines. 

The regioselective 2 -0-debenzoylation of fully benzoylated purine and pyrimidine ribonucleosides using hydrazine hydrate is mentioned in Chapter 21. 

Imidazo[l,2-c]pyrimidine nucleosides containing jS-D-ribofuranosyl and jS-D-arabinofuranosyl residues, imidazo[l,2-a]pyrimidine ribonucleosides, 4-amino-5-P-D-ribofuranosyl-5-azaindole, and l-(2-deoxy-a- and -D-erythro pentofuranosyl)indoles have been reported. 

Treatment of 5-fluorocytidine with acetylsalicyloyl chloride yielded 0, 2 -cyclo-6-D-arabinofuranosyl-5-fluorocytosine, which on hydrolysis afforded 3-D-arabinofuranosylcytosine. A general procedure for the synthesis of specifically labelled pyrimidine ribonucleosides,including [5 - 0] and [0-2,5 - J-uridine, utilizes 0-2,5 -anhydro-2, 3 -0-isopropylideneuridine with [ 0] sodium hydroxide. 6,5 -Cyclo-5-deoxyuridine has been prep-... 

---