PNA versus DNA: effects of structural fluctuations on electronic structure and hole-transport mechanisms.
The effects of structural fluctuations on charge transfer in double-stranded DNA and peptide nucleic acid (PNA) are investigated. A palindromic sequence with two guanine bases that play the roles of hole donor and acceptor, separated by a bridge of two adenine bases, was analyzed using combined molecular dynamics (MD) and quantum-chemical methods. Surprisingly, electronic structure calculations on individual MD snapshots show significant frontier orbital electronic population on the bridge in approximately 10% of the structures. Electron-density delocalization to the bridge is found to be gated by fluctuations of the covalent conjugated bond structure of the aromatic rings of the nucleic bases. It is concluded, therefore, that both thermal hopping and superexchange should contribute significantly to charge transfer even in short DNA/PNA fragments. PNA is found to be more flexible than DNA, and this flexibility is predicted to produce larger rates of charge transfer.
Hatcher
Elizabeth
E
Department of Chemistry, Duke University, French Family Science Center, Durham, North Carolina 27708, USA.
Balaeff
Alexander
A
Keinan
Shahar
S
Venkatramani
Ravindra
R
Beratan
David N
DN
D004247:DNA / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D020135:Peptide Nucleic Acids / Q000737:chemistry*; D011789:Quantum Theory
D020135:Peptide Nucleic Acids; D004247:DNA