A conformational transition in the structure of a 2′-thiomethyl- modified DNA visualized at high resolution

Abstract

Crystal structures of A-form and B-form DNA duplexes containing 2′-S-methyl-uridines reveal that the modified residues adopt a RNA-like C3′-endo pucker, illustrating that the replacement of electronegative oxygen at the 2′-carbon of RNA by sulfur does not appear to fundamentally alter the conformational preference of the sugar in the oligonucleotide context and sterics trump stereoelectronics. © 2009 The Royal Society of Chemistry.