Sodium-Ion Binding to DNA: Detection by Ultrafast Time-Resolved Stokes-Shift Spectroscopy
- 6 September 2003
- journal article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 125 (39) , 11812-11813
- https://doi.org/10.1021/ja0363617
Abstract
The nature of the counterion is shown to have a pronounced effect on the apparent dynamic polarity in the interior of DNA. Time-resolved Stokes-shift measurements in the 80 ps to 40 ns time range were made on a polarity-sensitive fluorophore (coumarin 102) that replaces a base pair in an oligonucleotide. With sodium counterions, the emission spectrum narrows with time, whereas with tetrabutylammonium counterions, it does not. Our interpretation is that a subpopulation of helices have sodium cations bound in a fashion that slows the normal dynamics.Keywords
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