Can Copper(II) Mediate Hoogsteen Base-Pairing in a Left-Handed DNA Duplex? A Pulse EPR Study.

Maria Grazia Santangelo, Gunnar Jeschke, Bernhard Spingler, Maria Grazia Santangelo, Philipp M. Antoni

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

Pulse EPR spectroscopy is used to investigate possible structural features of the copper(II) ion coordinated to poly(dG-dC)poly(dG-dC) in a frozen aqueous solution, and the structural changes of the polynucleotide induced by the presence of the metal ion. Two different copper species were identified and their geometry explained by a molecular model. According to this model, one species is exclusively coordinated to a single guanine with the N7 nitrogen atom forming a coordinative bond with the copper. In the other species, a guanine and a cytosine form a ternary complex together with the copper ion. A copper crosslink between the N7 of guanine and N3 of cytosine is proposed as the most probable coordination site. Moreover, no evidence was found for an interaction of either copper species with a phosphate group or equatorial water molecules. In addition, circular dichroism (CD) spectroscopy showed that the DNA of the Cu(II)-poly(dG-dC)poly(dG-dC) adducts resembles the left-handed Z-form. These results suggest that metal-mediated Hoogsteen base pairing, as previously proposed for a right-handed DNA duplex, can also occur in a double-stranded left-handed DNA.
Original languageEnglish
Pages (from-to)599-606
Number of pages7
JournalChemPhysChem
Volume11
Publication statusPublished - 2010

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry

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