2 research outputs found

    Charge Transfer through Modified Peptide Nucleic Acids

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    We studied the charge transfer properties of bipyridine-modified peptide nucleic acid (PNA) in the absence and presence of Zn­(II). Characterization of the PNA in solution showed that Zn­(II) interacts with the bipyridine ligands, but the stability of the duplexes was not affected significantly by the binding of Zn­(II). The charge transfer properties of these molecules were examined by electrochemistry for self-assembled monolayers of ferrocene-terminated PNAs and by conductive probe atomic force microscopy for cysteine-terminated PNAs. Both electrochemical and single molecular studies showed that the bipyridine modification and Zn­(II) binding do not affect significantly the charge transfer of the PNA duplexes

    Effect of Backbone Flexibility on Charge Transfer Rates in Peptide Nucleic Acid Duplexes

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    Charge transfer (CT) properties are compared between peptide nucleic acid structures with an aminoethylglycine backbone (aeg-PNA) and those with a γ-methylated backbone (γ-PNA). The common aeg-PNA is an achiral molecule with a flexible structure, whereas γ-PNA is a chiral molecule with a significantly more rigid structure than aeg-PNA. Electrochemical measurements show that the CT rate constant through an aeg-PNA bridging unit is twice the CT rate constant through a γ-PNA bridging unit. Theoretical calculations of PNA electronic properties, which are based on a molecular dynamics structural ensemble, reveal that the difference in the CT rate constant results from the difference in the extent of backbone fluctuations of aeg- and γ-PNA. In particular, fluctuations of the backbone affect the local electric field that broadens the energy levels of the PNA nucleobases. The greater flexibility of the aeg-PNA gives rise to more broadening, and a more frequent appearance of high-CT rate conformations than in γ-PNA
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