Magnetic field induced residual dipolar couplings of imino groups in nucleic acids from measurements at a single magnetic field.
For base-paired nucleic acids, variations in (1) J (NH) and the imino (1)H chemical shift are both dominated by hydrogen bond length. In the absence of molecular alignment, the (1) J (NH) coupling for the imino proton then can be approximated by (1) J (NH) = (1.21Hz/ppm)delta(H) - 103.5 +/- 0.6 Hz, where delta(H) represents the chemical shift of the imino proton in ppm. This relation permits imino residual dipolar couplings (RDCs) resulting from magnetic susceptibility anisotropy (MSA) to be extracted from measurement of ((1) J (NH) + RDC) splittings at a single magnetic field strength. Magnetic field-induced RDCs were measured for tRNA(Val) and the alignment tensor determined from magnetic-field alignment of tRNA(Val) agrees well with the tensor calculated by summation of the MSA tensors of the individual nucleobases.
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Jinfa
J
Ying
Alexander
A
Grishaev
Michael P
MP
Latham
Arthur
A
Pardi
Ad
A
Bax
D016880:Anisotropy; D007097:Imines / Q000737:chemistry*; D008280:Magnetics; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D009696:Nucleic Acids / Q000737:chemistry*; D011522:Protons; D012366:RNA, Transfer, Val / Q000737:chemistry
D007097:Imines; D009587:Nitrogen Isotopes; D009696:Nucleic Acids; D011522:Protons; D012366:RNA, Transfer, Val