Observation of coherent delocalized phonon-like modes in DNA under physiological conditions
Mario González-Jiménez, Gopakumar Ramakrishnan, Thomas Harwood, Adrian J. Lapthorn, Sharon M. Kelly, Elizabeth M. Ellis & Klaas Wynne
Nature Communications 7, Article number: 11799 doi:10.1038/ncomms11799
Received 12 February 2016 Accepted 28 April 2016 Published 01 June 2016
Underdamped terahertz-frequency delocalized phonon-like modes have long been suggested to play a role in the biological function of DNA. Such phonon modes involve the collective motion of many atoms and are prerequisite to understanding the molecular nature of macroscopic conformational changes and related biochemical phenomena. Initial predictions were based on simple theoretical models of DNA. However, such models do not take into account strong interactions with the surrounding water, which is likely to cause phonon modes to be heavily damped and localized. Here we apply state-of-the-art femtosecond optical Kerr effect spectroscopy, which is currently the only technique capable of taking low-frequency (GHz to THz) vibrational spectra in solution. We are able to demonstrate that phonon modes involving the hydrogen bond network between the strands exist in DNA at physiologically relevant conditions. In addition, the dynamics of the solvating water molecules is slowed down by about a factor of 20 compared with the bulk.
Subject terms: Physical sciences Biophysics Physical chemistry Molecular biology
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