Guanine deoxyriboside

In one of the few known attempts to prepare a deoxyriboside, 2-deoxy-3,5-di-0-p-tolyl-D-eo t/jr(>-pentofuranosyl chloride and the sUylated 8-aza-guanine gave a mixture of both a and fi anomers, of which the p has the... 

Table 27-1 gives the nomenclature of purine and pyrimidine nucleosides and nucleotides. Names of purine nucleosides end in -osine, whereas those of pyrimidine nucleosides end in -idine guanine nucleoside is guanosine and should not be confused with guanidine, which is not a nucleic acid base thymidine is a deoxyriboside. 

Fig. 11.1.3. Reversed phase HPLC of nucleic acid bases and nucleosides. Chromatographic conditions column, Spherisorb ODS-2, 5 pm (250 x 4.6 mm) mobile phase, 0.05 M monobasic ammonium phosphate, pH 3.5 flow rate, 1.5 ml/min temperature, ambient detection, UV at 260 nm. Peaks C, cytosine U, uracil FU, fluorouracil CR, cytosine riboside A, adenine CdR, cytosine deoxyriboside UR, uracil riboside T, thymine FUR, fluorouracil riboside UdR, uracil deoxyriboside, FUdR, fluorouracil deoxyriboside GR, guanine riboside GdR, guanosine deoxyriboside TdR, thymine deoxyriboside AR, adenine riboside. Reproduced from Miller et al. (1982), with...

However, for adenine, guanine, and uracil, the dominant route of anabolism is by way of their ribonucleotide derivatives and traffic along the deoxyribosidic route is not ordinarily significant. Because cytosine is not a substrate for nucleoside phosphorylases, incorporation by the phos-phorylase-kinase route is not possible for this base. The other pyrimidine base of DNA, thymine, is poorly anabolized by both animal and bacterial cells, in spite of the fact that most cells possess thymidine phosphorylase, the action of which is readily reversible. This suggests that ordinarily cellular supplies of deoxyribose 1-phosphate are not available for base anabolism. Experiments are cited below in which it was demonstrated that a significant contribution to the biogenesis of deoxyribose of DNA in E. colt cells did not occur by a route other than ribonucleotide reduction. 

The fate of other purine-ribose compounds was studied in the rat and it was found that C Mabeled adenosine (211) and adenylic acid (212) were utilized for the s3Tithesis of RNA adenine and guanine, but to a much smaller extent than adenine (191). Similarly, growing yeast utilized the purine base, adenine, far more readily than the corresponding nucleoside or nucleotide (195). It was believed that the ribose derivatives were poorly utilized because they were first cleaved to free adenine, which was incorporated subsequently into polynucleotides. It is curious that the attachment of ribose or a ribose pho hate moiety to adenine or guanine did not facilitate their incorporation into nucleic acids. In contrast, inosine, the ribonucleoside of hypoxantbine, was utilized considerably by the rat as a nucleic acid precursor (211) the corresponding deoxyriboside, deoxyinosine, was not (213). 

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