Proton magnetic resonance analysis of terbium ion-nucleic acid complexes: Further evidence for two-site binding to polynucleotides

David S. Gross, Henry Simpkins, Edward Bubienko, Philip N. Borer

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Terbium ion (Tb3+), like other rare earth lanthanides, has traditionally been viewed as binding nucleic acids at or near their ionized phosphate groups only. Here evidence is presented from 1H NMR studies that confirms this mode of binding in Tb3+-mono-nucleotide complexes. However, in polynucleotides, we find that Tb3+ coordinately binds at two distinct sites, the phosphate moiety and electron donor groups on purine and pyrimidine bases. This two-site binding is best illustrated by complexes of Tb3+-polyuridylic acid, where the relative sensitivities of the uracil protons H5 and H6 to induced chemical shift and nuclear spin relaxation are the inverse of that seen in Tb3+-uridine monophosphate complexes. These data substantiate recently reported results derived from ultraviolet absorption and fluorescence spectroscopy (D. S. Gross and H. Simpkins, 1981, J. Biol. Chem.256, 9593-9598) that two-site binding is characteristic of the terbium(III)-polynucleotide interaction.

Original languageEnglish (US)
Pages (from-to)401-410
Number of pages10
JournalArchives of Biochemistry and Biophysics
Volume219
Issue number2
DOIs
StatePublished - Dec 1982

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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