Base-pair induced shifts in the tautomeric equilibrium of a modified DNA base

G. Victor Fazakerley, Zofia Gdaniec, Lawrence C. Sowers

Research output: Contribution to journalEditorialpeer-review

45 Scopus citations


We have examined the base-pairing properties of N 4 -methoxycytosine (mo 4 C), a mutagenic base analog, in DNA by nuclear magnetic resonance spectroscopy. Unlike standard bases, the tautomeric equilibrium of mo 4 C could be strongly influenced by base-pair formation. Paired with A, mo 4 C is found predominantly in the imino configuration in Watson-Crick geometry. However, when paired with G, two structurally distinct configurations are observed in equilibrium with one another. In one configuration, mo 4 C is in the amino form paired with G in Watson-Crick geometry. In the second species, mo 4 C is in the imino configuration paired with G in a wobble geometry. This is the first demonstration of base-pair induced tautomeric shifts in DNA and supports the hypothesis that rare tautomeric forms may be involved in mutagenesis.

Original languageEnglish (US)
Pages (from-to)6-10
Number of pages5
JournalJournal of Molecular Biology
Issue number1
StatePublished - Mar 5 1993
Externally publishedYes


  • DNA
  • Mutagenesis
  • Oligonucleotide
  • Tautomerism
  • n.m.r

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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