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The Effect of Varied Ion Distributions on Long-Range DNA Charge Transport

Williams, Tashica T. and Barton, Jacqueline K. (2002) The Effect of Varied Ion Distributions on Long-Range DNA Charge Transport. Journal of the American Chemical Society, 124 (9). pp. 1840-1841. ISSN 0002-7863. doi:10.1021/ja012217e.

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Long-range oxidative damage to DNA was utilized as a probe to delineate the effects of different ion distributions on DNA charge transport. DNA assemblies were constructed, containing a tethered rhodium intercalating photooxidant, spatially separated from two 5‘-GG-3‘ sites of oxidative damage, with either an A_6-tract or a mixed DNA sequence intervening between the guanine doublets; the extent of charge transport was assessed through measurements of the ratio of yields of damage at the guanine doublet distal versus that proximal to the metal binding site. The distal/proximal damage ratios were compared after photooxidation of otherwise identical Rh-tethered assemblies, except for ^(32)P-labeling either at the 5‘- or 3‘-end; this labeling difference corresponds, in the absence of charge neutralization by condensed counterions, to a shift in negative charge from one end of the duplex to the other. Both with assemblies containing the mixed sequence and the A_6-tract, we observed that moving the negative charges to the proximal end of the duplex significantly decreased hole transport to the distal end. We propose that these results reflect variations in the thermodynamic potential at the proximal and distal guanine sites because of the change in charges at the termini of the oligomer. High values for the internal dielectric constant of the stacked base pairs are suggested by these data. Hence, the longitudinal polarizability of DNA may be important to consider in mechanisms for long-range DNA charge transport.

Item Type:Article
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Barton, Jacqueline K.0000-0001-9883-1600
Additional Information:© 2002 American Chemical Society. Received September 24, 2001. Publication Date (Web): February 6, 2002. We are grateful to the NIH for their financial support (GM49216) and to the NSF for a predoctoral fellowship (T.T.W.) We also thank D.M. Crothers for his suggestions.
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NSF Predoctoral FellowshipUNSPECIFIED
Issue or Number:9
Record Number:CaltechAUTHORS:20160208-152444728
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Official Citation:The Effect of Varied Ion Distributions on Long-Range DNA Charge Transport Tashica T. Williams and Jacqueline K. Barton Journal of the American Chemical Society 2002 124 (9), 1840-1841 DOI: 10.1021/ja012217e
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:64316
Deposited By: George Porter
Deposited On:08 Feb 2016 23:37
Last Modified:10 Nov 2021 23:29

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