Ribonucleoside, defined

Transfer RNA precursors may undergo further posttranscriptional processing. The 3 -terminal trinucleotide CCA(3 ) to which an amino acid will be attached during protein synthesis (Chapter 27) is absent from some bacterial and all eukaryotic tRNA precursors and is added during processing (Fig. 26-23). This addition is carried out by tRNA nucleotidyltransferase, an unusual enzyme that binds the three ribonucleoside triphosphate precursors in separate active sites and catalyzes formation of the phosphodiester bonds to produce the CCA(3 ) sequence. The creation of this defined sequence of nucleotides is therefore not dependent on a DNA or RNA template—the template is the binding site of the enzyme. 

Leonard and co-workers have synthesized de novo analogues of the purines, and especially of adenine, that differ from the natural bases, ribonucleosides, or ribonucleotides by defined dimen-... 

The structure of purine ribonucleosides has recently been studied by proton-magnetic resonance, and the conformation of the D-ribofuranosyl residue in adenosine and inosine has been determined by an analysis of proton-magnetic resonance data C-2 is considered to be out of the plane defined either by C-1, 0, and C-4 or by C-1, 0, C-3, and C-4 and is pointing on the same side as the C-4—C-5 bond. A similar study of deoxy-ribonucleosides suggests that the ring-oxygen atom and, possibly, C-1 of this sugar moiety may be twisted out of the plane of the five-membered... 

This report covers the literature relating to mono- and dinucleotides that were published between January 2008 and January 2009. One particular area, which will potentially have a major impact on future nucleotide research, is the newly acquired accessibility to stereoregular oligodeoxy-ribonucleoside phosphorothioates using chirally defined oxazaphos-pholidines monomers. Other notable developments during this period include the further advances made in the chemistry of polyphosphate nucleosides and dinucleotides, details of which are found in the following sections. 

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