Hole trapping, detrapping, and hopping in DNA

M. Bixon*, Joshua Jortner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

53 Scopus citations

Abstract

In this paper we present a self-consistent kinetic-quantum mechanical analysis of chemical yield data for hole trapping/detrapping in G+(T-A)mGGG duplexes (with free energy gaps Δt) and for hole hopping/trapping/detrapping in G+[(T)mG]n(T)mGGG duplexes of DNA. Bridge specificity of hole trapping/detrapping by GGG traps was specified by superexchange electronic contributions, inferred from electronic coupling matrix elements between nearest-neighbor nucleobases and semiempirical energy gaps, and energetic contributions, which determine the nuclear Franck-Condon factors. Unistep hole-trapping yields are accounted for by a weak bridge length dependence for short (N = 1, 2) bridges, due to detrapping. Marked bridge specificity is manifested for short (N = 1, 2) bridges, being distinct for (T)N and for [(A)m+1(T)m']n (m, m' ≥ 0 and N = n(m + m' + 1)) bridges. For long (N > 2) bridges an exponential bridge size dependence of the trapping yields prevails. Multistep hole transport results in different reaction rates of G+ (rate kd) and of (GGG)+ (rate kdt) with water, i.e., kd/kdt = 1.6, which, in conjunction with the unistep trapping/detrapping data, results in the free energy gaps for hole trapping of Δt = 0.096 eV in the G+(T)NGGG duplexes and of Δt = 0.062 eV in the G+[(A)m+1(T)m']nGGG duplexes.

Original languageEnglish
Pages (from-to)10322-10328
Number of pages7
JournalJournal of Physical Chemistry A
Volume105
Issue number45
DOIs
StatePublished - 15 Nov 2001

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