Ultrafast dynamics in DNA: "Fraying" at the end of the helix

Daniele Andreatta, Sobhan Sen, J. Luis Pérez Lustres, Sergey A. Kovalenko, Nikolaus P. Ernsting, Catherine J. Murphy, Robert S. Coleman, Mark A. Berg

Research output: Contribution to journalArticlepeer-review


The dynamics of the electric fields in the interior of DNA are measured by using oligonucleotides in which a native base pair is replaced by a dye molecule (coumarin 102) whose emission spectrum is sensitive to the local electric field. Time resolved measurements of the emission pectrum have been extended to a six decade time range (40 fs to 40 ns) by combining results from time-correlated photon counting, flourescence up-conversion, the transient absorption. Recent results showed that when the reporter is placed in the center of the oligonucleotide, the dynamics are very broadly distributed over this entire time range and do not show specific time constants associated with individual processes (Andreatta D.; et al. J. Am Chem. Soc. 2005, 127, 7270). This paper examines an oligonucleotide with the reporter near its end. The broadly distributed relaxation seen before remains with little attenuation. In addition, a new relaxation with a well-defined relaxation time of 5 ps appears. This process is assigned to the rapid component of "fraying" at the end of the helix.

Original languageEnglish (US)
Pages (from-to)6885-6892
Number of pages8
JournalJournal of the American Chemical Society
Issue number21
StatePublished - May 31 2006
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry


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