title: Conversions of poly(2-aminodeoxyadenylate-5-halodeoxyuridylate) from B to A forms in high salt. An NMR and circular dichroism study.
abstract: Proton one- and two-dimensional nuclear Overhauser enhancement (1D and 2D NOE) spectroscopy has been used to demonstrate that poly(d2NH2A-d5IU) and poly(d2NH2A-d5BrU) are converted from the B to the A conformation in high salt, as found previously for poly(d2NH2A-dT) [Borah, B., Cohen, J. S., Howard, F. B., & Miles, H. T. (1985) Biochemistry 24, 7456-7462]. The 2D NOE and 1D NOE spectra exhibit strong base proton (H8,H6)-H3' cross relaxation, suggesting short interproton distances. These results are indicative of a C3'-endo sugar pucker for both purine and pyrimidine residues in an A or closely related structure. The circular dichroism and UV spectra are consistent with the interpretation of an A conformation in high salt.
mesh_terms: D002942:Circular Dichroism / Q000379:methods; D007202:Indicators and Reagents; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007202:Indicators and Reagents; D009838:Oligodeoxyribonucleotides; C050966:poly(2-aminodeoxyadenylate-5-iododeoxyuridylate); C050967:poly(2-aminodeoxyadenylate-5-bromodeoxyuridylate)