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DNA-Mediated Charge Transport Requires Conformational Motion of the DNA Bases: Elimination of Charge Transport in Rigid Glasses at 77 K

O'Neill, Melanie A. and Barton, Jacqueline K. (2004) DNA-Mediated Charge Transport Requires Conformational Motion of the DNA Bases: Elimination of Charge Transport in Rigid Glasses at 77 K. Journal of the American Chemical Society, 126 (41). pp. 13234-13235. ISSN 0002-7863. doi:10.1021/ja0455897. https://resolver.caltech.edu/CaltechAUTHORS:20170421-084130900

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Abstract

We have proposed that DNA-mediated charge transport (CT) is gated by base motions, with only certain base conformations being CT-active; a CT-active conformation can be described as a domain, a transiently extended π-orbital defined dynamically by DNA sequence. Here, to explore these CT-active conformations, we examine the yield of base-base CT between photoexcited 2-aminopurine (Ap*) and guanine in DNA in rigid LiCl glasses at 77 K, where conformational rearrangement is effectively eliminated. Duplex DNA assemblies (35-mers) were constructed containing adenine bridges Ap(A)_nG (n = 0−4). The yield of CT was monitored through fluorescence quenching of Ap* by G. We find, first, that the emission intensity of Ap* in all DNA duplexes increases dramatically upon cooling and becomes comparable to free Ap*. This indicates that all quenching of Ap* in duplex DNA is a dynamic process that requires conformational motion of the DNA bases. Second, DNA-mediated CT between Ap* and G is not observed at 77 K; rather than hindering the ability of DNA to transport charge, conformational motion is required. Moreover, the lack of DNA-mediated CT at 77 K, even through the shortest bridge, suggests that the static structures adopted upon cooling do not represent optimum CT-active conformations. These observations are consistent with our model of conformationally gated CT. Through conformational motion of the DNA bases, CT-active domains form and break-up transiently, both facilitating and limiting CT.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/ja0455897DOIArticle
http://pubs.acs.org/doi/abs/10.1021/ja0455897PublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/ja0455897PublisherSupporting Information
ORCID:
AuthorORCID
Barton, Jacqueline K.0000-0001-9883-1600
Additional Information:© 2004 American Chemical Society. Received July 22, 2004. Publication Date (Web): September 25, 2004. We acknowledge the NIH and NFCR. M.A.O. thanks NSERC for a postdoctoral fellowship.
Funders:
Funding AgencyGrant Number
NIHUNSPECIFIED
National Foundation for Cancer ResearchUNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Issue or Number:41
DOI:10.1021/ja0455897
Record Number:CaltechAUTHORS:20170421-084130900
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170421-084130900
Official Citation:DNA-Mediated Charge Transport Requires Conformational Motion of the DNA Bases:  Elimination of Charge Transport in Rigid Glasses at 77 K Melanie A. O‘Neill and Jacqueline K. Barton Journal of the American Chemical Society 2004 126 (41), 13234-13235 DOI: 10.1021/ja0455897
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:76802
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:21 Apr 2017 18:29
Last Modified:15 Nov 2021 17:02

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