title: Stereodynamics of dimer segments of RNA in aqueous solution.
abstract: Arguments are presented which show that conformations II and III proposed by Lee and Tinoco [Lee, C.H., and Tinoco, I., Jr. (1977), Biochemistry 16, 5403] for ribodinucleoside monophosphates in aqueous solution are untenable. It has been shown that ribodinucleoside monophosphates exist in aqueous solution as an equilibrium blend of the classically recognized right-handed stack (g-g-), loop stack (g+g+), skewed (g+t), and extended arrays. In order to determine the effect of epsilonA base on the conformer distribution in the equilibrium blend, detailed ring-current calculations were performed and the isoshielding curves for epsilonA were derived. Use of these curves vis-a-vis dimerization shift data indicates that introduction of epsilonA perturbs the equilibrium blend which causes an increase in the population of skewed (g+t) arrays.
mesh_terms: D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D009690:Nucleic Acid Conformation; D012313:RNA; D012265:Ribonucleotides; D014867:Water; D014961:X-Ray Diffraction
chemical_list: D012265:Ribonucleotides; D014867:Water; D012313:RNA