Ribose modifications

A series of 2 -5 oligoadenylate analogues (48) containing intemucleoside and ribose modifications has been prepared by solid-phase methods as potential interferon mimetics. ... 

GpppG), dinucleotides (NpG), terminal monophosphate (pG, thio-G) and photoreactive nucleotides at the 5 -end. However, incorporation of nucleotides with ribose modifications requires some adjustments as described in Section 2.3.2.2. 

In addition to the variety of modifications found on the heterocyclic base discussed above, many nucleosides are also methylated at the 2 -hydroxyl of the ribose moiety and make up approximately 8 % of existing tRNA modifications. One interesting example of the 2 - 0-ribose modification was studied in S. cerevisiae, where the yeast tRNA molecules corresponding to His, Pro, and Gly(G-C-C) contain a 2 -0-methylated nucleoside at position 4 in the acceptor stem. A methylated cytosine is found in tRNA ° and tRNA, and the modified Am nucleoside is found in tRNA . Modifications in a duplex region of tRNA are very rare, yet modification at this position ( 4) is conserved in eukaryotes. A yeast knock-out strain of the gene trmlS was produced, and it was determined by HPLC and primer extension analysis that tRNAs purified from this organism did not exhibit the 2 - 0-methyl modification at position 4. 

Mono- and poly-ADP-ribosylation. Mono-ADP-ribosylation and poly(ADP-ribose) modification catalyzed by ADP-ribosyl transferase and poly(ribose) synthetase respectively, append mono- and poly ADP-ribose (ADPR) moieties (Hayaishi and Ueda, 1977). In poly ADPR, the polymeric chain consists of woADP-ribose, 2 -(5"-phosphoribosyl)-5 -AMP... 

The present study represents an attempt to characterize the proteins undergoing poly-(ADP-ribose) modification in association with myogenesis. Although we have not yet performed analysis of poly(ADP-ribose) conjugates of histones which are the main acceptors in many systems [20, 21], several interesting observations have emerged from our study. 

Fig. 4. DNA-protein interactions in isolated nucleosomal core particles following poly(ADP-ribose)-modification in vitro, Nucleosomal core particles were prepared as described (6, 7) and incubated as indicated. Subsequent gel mobility shift analysis was performed as described (7), using DNA restriction markers of 830,560, and 140 bp.

Table 3. Consequences of the elevation of intracellular NAD concentrations on the level of poly(ADP-ribose) modification of hepatocellular chromatin and the ratio between ADP-ribosyl residues contained in NAD and poly(ADP-ribose)...

Peacock H, Fucini RV, Jayalath P, Ibarra-Soza JM, Haringsma HI, Ranagan WM, Willingham A, Beal PA (2011) Nucleobase and ribose modifications control immunostimulation by a microRNA-122-mimetic RNA. J Am Chem Soc 133 9200-9203... 

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