31P NMR relaxation measurements of the phosphate backbone of a double stranded hexadeoxynucleotide in solution: determination of the chemical shift anisotropy

M. J. Forster, A. N. Lane

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

The five phosphates of the deoxynucleotide d(CpGpTpApCpG)2 have been assigned by two-dimensional heteronuclear NMR spectroscopy. The chemical shift anisotropy and correlation time of each phosphate group has been determined from measurements of the spin-lattice, spin-spin relaxation rate constants and the 31P-{1H} nuclear Overhauser enhancement (NOE) at three magnetic field strengths (4.7 T, 9.4 T, and 11.75 T) and two temperatures (288 K and 298 K). As expected, the relaxation data require two mechanisms to account for the observed rate constants, i.e. dipole-dipole and chemical shift anisotropy. At 9.4 T and 11.75 T, the latter mechanism dominates the relaxation, leading to insignificant NOE intensities. The correlation time, chemical shift anisotropy and effective P-H distance were obtained from least-squares fitting to the data. Comparison of the fitted value for the correlation time with that obtained from 1H measurements shows that the molecule behaves essentially as rigid rotor on the nanosecond timescale. Large amplitude motions observed in long segments of DNA are due to bending motions that do not contribute significantly to relaxation in short oligonucleotides.

Original languageEnglish
Pages (from-to)347-355
Number of pages9
JournalEuropean Biophysics Journal
Volume18
Issue number6
DOIs
StatePublished - Jul 1990

Keywords

  • P relaxation
  • Chemical shift anisotropy
  • DNA dynamics

ASJC Scopus subject areas

  • Biophysics

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