Journal Article

Effect of lesions on the dynamics of DNA on the picosecond and nanosecond timescales using a polarity sensitive probe

Mark M. Somoza, Daniele Andreatta, Catherine J. Murphy, Robert S. Coleman and Mark A. Berg

in Nucleic Acids Research

Volume 32, issue 8, pages 2494-2507
Published in print April 2004 | ISSN: 0305-1048
Published online April 2004 | e-ISSN: 1362-4962 | DOI: https://dx.doi.org/10.1093/nar/gkh577
Effect of lesions on the dynamics of DNA on the picosecond and nanosecond timescales using a polarity sensitive probe

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This paper explores the effects of structural modifications on the fast dynamics of DNA and the ability of time‐resolved Stokes shift spectroscopy to measure those changes. The time‐resolved Stokes shift of a synthetic coumarin base‐pair replacement within an oligomer is measured between 40 ps and 40 ns. Comparisons are made between 17mers without modification, with a deleted base near the coumarin and with the coumarin placed near the end of the oligomer. The deletion of a next‐to‐nearest‐neighbor base pair does not change the subnanosecond dynamics, but does cause an additional motion with a time constant of ∼20 ns. A candidate for this motion is the flipping of the abasic sugar out of the helix and the concomitant intrusion of water into the interior of the helix. A nearby chain end causes little change in the dynamics after 1 ns but leads to a reduction in the amplitude of the dynamics between 40 ps and 1 ns. We suggest that at the chain end, where DNA on one side of the probe has been replaced by water, the charge‐ stabilizing dynamics have the same overall amplitude, but that much of the relaxation occurs before the start of the measurement time window.

Journal Article.  12098 words.  Illustrated.

Subjects: Research Methods in Life Sciences

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