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Cover Picture: Oligoribonucleotide Analogues Containing a Mixed Backbone of Phosphodiester and Formacetal Internucleoside Linkages, Together with Vicinal 2'-O-Methyl Groups (ChemBioChem 5/2007)
The cover picture shows the chemical structure and a 3D representation (unoptimized Chem3D model) of RNA with hydrophobic chemical modifications. Replacement of selected phosphodiesters with formacetal linkages (blue) and methylation of the adjacent 2'-hydroxyl groups (red) have independent and additive positive effects on the thermal stability of the RNA helices. Biophysical studies suggest that several complementary factors—reduction of electrostatic repulsion, solvation changes, conformational preorganization, hydrophobic interactions, etc.—interact to produce the observed stabilization. Modifications of RNA's sugar–phosphate backbone can be used to tune the thermal and enzymatic stability, hydrophobicity and electrostatic properties of RNA molecules. Chemically modified RNA has potential applications in gene-control technologies, such as antisense and RNA interference. Further details can be found in the article by E. Rozners, et al. on p. 537 ff.