title: A RNA.DNA hybrid that can adopt two conformations: an x-ray diffraction study of poly(rA).poly(dT) in concentrated solution or in fibers.
abstract: The RNA.DNA hybrid poly(rA).poly(dT) can adopt two conformations, depending upon its degree of hydration. Fibers yield a conventional A' RNA-like pattern at 79% relative humidity. In contrast, under highly solvated conditions this material yields an x-ray diffraction pattern with striking similarities to that of B DNA and clearly different from the RNA-like diffraction patterns previously obtained from fibers of other hybrids. A structural model is proposed for the solution form of the hybrid that has several similarities to models proposed for B DNA. The hybrid model accommodates the 2'-hydroxyl groups of the poly(rA) strand in intrachain hydrogen bonds to the adjacent ribose moieties.
mesh_terms: D008956:Models, Chemical; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D011061:Poly A; D011071:Poly T; D011089:Polydeoxyribonucleotides; D014961:X-Ray Diffraction
chemical_list: D011089:Polydeoxyribonucleotides; D011061:Poly A; D011071:Poly T