title: Deuterium isotope effects and fractionation factors of hydrogen-bonded A:T base pairs of DNA.
abstract: Deuterium isotope effects and fractionation factors of N1.H3-N3 hydrogen bonded Watson-Crick A:T base pairs of two DNA dodecamers are presented here. Specifically, two-bond deuterium isotope effects on the chemical shifts of (13)C2 and (13)C4, (2)delta(13)C2 and (2)delta(13)C4, and equilibrium deuterium/protium fractionation factors of H3, Phi, were measured and seen to correlate with the chemical shift of the corresponding imino proton, delta(H3). Downfield-shifted imino protons associated with larger values of (2)delta(13)C2 and (2)delta(13)C4 and smaller Phi values, which together suggested that the effective H3-N3 vibrational potentials were more anharmonic in the stronger hydrogen bonds of these DNA molecules. We anticipate that (2)delta(13)C2, (2)delta(13)C4 and Phi values can be useful gauges of hydrogen bond strength of A:T base pairs.
authors.affiliation: Texas A&M University, Departments of Biochemistry & Biophysics, College Station, TX 77843, USA.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Vakonakis
authors.forename: Miguel
authors.initials: M
authors.lastname: Salazar
authors.forename: Mijeong
authors.initials: M
authors.lastname: Kang
authors.forename: Kim R
authors.initials: KR
authors.lastname: Dunbar
authors.forename: Andy C
authors.initials: AC
authors.lastname: LiWang
mesh_terms: D000225:Adenine / Q000737:chemistry*; D020029:Base Pairing; D004247:DNA / Q000737:chemistry*; D003903:Deuterium; D005815:Genetic Code; D006860:Hydrogen Bonding; D007553:Isotope Labeling; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D009690:Nucleic Acid Conformation; D013941:Thymine / Q000737:chemistry*
chemical_list: D004247:DNA; D003903:Deuterium; D000225:Adenine; D013941:Thymine