A chemical approach for site-specific identification of NMR signals from protein side-chain NH<inf>3</inf><sup>+</sup> groups forming intermolecular ion pairs in protein-nucleic acid complexes

Kurtis M. Anderson, Dan Nguyen, Alexandre Esadze, Levani Zandrashvili, David G. Gorenstein, Junji Iwahara

Research output: Contribution to journalArticle

12 Scopus citations


Abstract Protein-nucleic acid interactions involve intermolecular ion pairs of protein side-chain and DNA or RNA phosphate groups. Using three protein-DNA complexes, we demonstrate that site-specific oxygen-to-sulfur substitution in phosphate groups allows for identification of NMR signals from the protein side-chain NH<inf>3</inf> <sup>+</sup> groups forming the intermolecular ion pairs. A characteristic change in their <sup>1</sup>H and <sup>15</sup>N resonances upon this modification (i.e., substitution of phosphate to phosphorodithioate) can represent a signature of an intermolecular ion pair. Hydrogen-bond scalar coupling between protein side-chain <sup>15</sup>N and DNA phosphorodithiaote <sup>31</sup>P nuclei provides direct confirmation of the intermolecular ion pair. The same approach is likely applicable to protein-RNA complexes as well.

Original languageEnglish (US)
Article number9909
Pages (from-to)1-5
Number of pages5
JournalJournal of Biomolecular NMR
Issue number1
StatePublished - Jun 1 2015



  • Hydrogen bonds
  • Ion pairs
  • NH<inf>3</inf><sup>+</sup> groups
  • Protein side chains
  • Protein-nucleic acid interactions

ASJC Scopus subject areas

  • Spectroscopy
  • Biochemistry

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