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Article: Tunneling energy effects on GC oxidation in DNA

TitleTunneling energy effects on GC oxidation in DNA
Authors
Issue Date2002
PublisherAmerican Chemical Society. The Journal's web site is located at http://www.pubs.acs.org/jpcb
Citation
Journal Of Physical Chemistry B, 2002, v. 106 n. 9, p. 2381-2392 How to Cite?
AbstractHole-mediated electronic couplings, reorganization energies, and electron transfer (ET) rates are examined theoretically for hole-transfer reactions in DNA. Electron transfer rates are found to depend critically on the energy gap between the donor/acceptor states and the intervening bases-the tunneling energy gap. The calculated distance decay exponent for the square of the electronic coupling, β, for hole transfer between GC base pairs (and pi-electron D/A pairs) ranges from 0.95 to 1.5 Å -1 in the model structures as the tunneling energy gap varies from 0.3 to 0.8 eV (which we argue is the range of energy gaps for GC oxidation probed in recent experiments). We show that the tunneling energy gap depends on the ET reorganization energy, which itself grows rapidly with distance for ET over 1-5 base pairs. Inclusion of the distance dependence of reorganization energies for these hole transfer reactions gives the tunneling rates an apparent decay exponent of ∼1.5-2.5 Å -1. We show that ET rates observed in DNA across one and two base pairs are reasonably well described with single-step ET theories, using our calculated couplings and reorganization energies. However, the computed single-step tunneling (superexchange) ET rates for donor and acceptor species separated by three or more base pairs are much smaller than observed. We conclude that longer-distance ET probably proceeds through thermal population of intermediate hole states of the bridging bases. Switching between mechanisms as distance grows beyond a few base pairs is likely to be a general characteristic of ET in small tunneling energy gap systems.
Persistent Identifierhttp://hdl.handle.net/10722/70389
ISSN
2001 Impact Factor: 3.379
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorTong, GSMen_HK
dc.contributor.authorKurnikov, IVen_HK
dc.contributor.authorBeratan, DNen_HK
dc.date.accessioned2010-09-06T06:22:25Z-
dc.date.available2010-09-06T06:22:25Z-
dc.date.issued2002en_HK
dc.identifier.citationJournal Of Physical Chemistry B, 2002, v. 106 n. 9, p. 2381-2392en_HK
dc.identifier.issn1089-5647en_HK
dc.identifier.urihttp://hdl.handle.net/10722/70389-
dc.description.abstractHole-mediated electronic couplings, reorganization energies, and electron transfer (ET) rates are examined theoretically for hole-transfer reactions in DNA. Electron transfer rates are found to depend critically on the energy gap between the donor/acceptor states and the intervening bases-the tunneling energy gap. The calculated distance decay exponent for the square of the electronic coupling, β, for hole transfer between GC base pairs (and pi-electron D/A pairs) ranges from 0.95 to 1.5 Å -1 in the model structures as the tunneling energy gap varies from 0.3 to 0.8 eV (which we argue is the range of energy gaps for GC oxidation probed in recent experiments). We show that the tunneling energy gap depends on the ET reorganization energy, which itself grows rapidly with distance for ET over 1-5 base pairs. Inclusion of the distance dependence of reorganization energies for these hole transfer reactions gives the tunneling rates an apparent decay exponent of ∼1.5-2.5 Å -1. We show that ET rates observed in DNA across one and two base pairs are reasonably well described with single-step ET theories, using our calculated couplings and reorganization energies. However, the computed single-step tunneling (superexchange) ET rates for donor and acceptor species separated by three or more base pairs are much smaller than observed. We conclude that longer-distance ET probably proceeds through thermal population of intermediate hole states of the bridging bases. Switching between mechanisms as distance grows beyond a few base pairs is likely to be a general characteristic of ET in small tunneling energy gap systems.en_HK
dc.languageengen_HK
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://www.pubs.acs.org/jpcben_HK
dc.relation.ispartofJournal of Physical Chemistry Ben_HK
dc.titleTunneling energy effects on GC oxidation in DNAen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=1520-6106&volume=106&issue=9&spage=2381&epage=2392&date=2002&atitle=Tunneling+Energy+effects+on+GC+oxidation+in+DNAen_HK
dc.identifier.emailTong, GSM:tongsm@hkucc.hku.hken_HK
dc.identifier.authorityTong, GSM=rp00790en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1021/jp013387gen_HK
dc.identifier.scopuseid_2-s2.0-0037035151en_HK
dc.identifier.hkuros114064en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0037035151&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume106en_HK
dc.identifier.issue9en_HK
dc.identifier.spage2381en_HK
dc.identifier.epage2392en_HK
dc.identifier.isiWOS:000174403200037-
dc.identifier.scopusauthoridTong, GSM=7102328656en_HK
dc.identifier.scopusauthoridKurnikov, IV=6602343152en_HK
dc.identifier.scopusauthoridBeratan, DN=7006677556en_HK

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