Phosphorus-31 nuclear magnetic resonance of ethidium complexes with ribonucleic acid model systems and phenylalanine-accepting transfer ribonucleic acid

Evelyn M. Goldfield, Bruce A. Luxon, Vickie Bowie, David G. Gorenstein

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The temperature dependence of the 31P NMR spectra of the ethidium complexes with poly(A)·oligo(U) and the 31P spectra of phenylalanine tRNA (yeast) in various molar ratios of ethidium ion (Et) are presented. In the poly(A)·oligo(U)·Et complex, a new peak about 2.0 ppm downfield from the double-helix peak appears. We have assigned this peak to phosphates perturbed by ethidium. The chemical shift of this peak is consistent with the intercalation mode of binding and provides additional support for our hypothesis that 31P shifts are sensitive probes of phosphate ester conformations. The main effect of ethidium on the 31P spectra of tRNAPhe is the broadening of several of the scattered signals. These scattered signals are associated with phosphates involved in tertiary interactions. We propose that these broadened signals arise from phosphates near the Et binding site.

Original languageEnglish (US)
Pages (from-to)3336-3344
Number of pages9
Issue number14
StatePublished - 1983
Externally publishedYes


ASJC Scopus subject areas

  • Biochemistry

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