P-N-Glycosidic bond

Steric hindrance by the base restricts rotation about the P-N-glycosidic bond of nucleosides and nu-... 

Posttranslational modification of preformed polynucleotides can generate additional bases such as pseudouridine, in which D-ribose is linked to C-5 of uracil by a carbon-to-carbon bond rather than by a P-N-glycosidic bond. The nucleotide pseudouridylic acid T arises by rearrangement of UMP of a preformed tRNA. Similarly, methylation by S-adenosylmethionine of a UMP of preformed tRNA forms TMP (thymidine monophosphate), which contains ribose rather than de-oxyribose. 

The Cl of D-ribose links N9 atom of adenine via a p N-glycosidic bond. ATP contains four chiral carbon atoms (Cl to C4 ) in its sugar moiety. Broken and thick arrows indicate the stereochemical features. 

The base adenine is bound to C-1 of ribose by an N-glycosidic bond (see p.36). In addition to C-2 to C-4, C-1 of ribose also represents a chiral center. The p-configuration is usually found in nucleotides. 

In nucleosides and nucleotides, the pentose residues are present in the furanose form (see p.34). The sugars and bases are linked by an N-glycosidic bond between the C-1 of the sugar and either the N-9 of the purine ring or N-1 of the pyrimidine ring. This bond always adopts the p-conflguration. 

Zheng Y, Cloutier P, Hunting DJ, Wagner JR, Sanche L (2006). Phosphodiester and N-glycosidic bond cleavage in DNA induced by 4-15 eV electrons. J Chem Phys 124 064710-064719. 

Fig. 5.17. N- and 0-glycosidic bonds. Adenosine triphosphate (ATP) contains a p, A-glycosidic bond. Lactose contains an 0-glycosidic P(1 —>4) bond. Glycogen contains a-1,4 and a-1,6 0-glycosidic bonds.

Most nucleosides contain D-ribose or 2-deoxy-D-ribose linked to N-1 of a pyrimidine or to N-9 of a purine by a P-glycosidic bond whose syn conformers predominate. 

Neisseria meningitidis serogroup K polysaccharide is composed of two iV-acetyl-(3-D-mannuronic acids, one of which is O-acetylated [-(l-4)-P-D-ManAAcA-(l-3)- 3-D-(490-Ac)-ManAAcA-]n [207]. It was shown to adopt the expected conformation with the protons across the glycosidic bonds HlAand H3B or H1B and H4A to be close together as demonstrated by large H-NMR nuclear Overhauser enhancements. 

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