title: Effect of backbone flexibility on charge transfer rates in peptide nucleic acid duplexes.
abstract: 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.
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pennsylvania 15260, United States.
authors.forename: Emil
authors.initials: E
authors.lastname: Wierzbinski
authors.forename: Arnie
authors.initials: A
authors.lastname: de Leon
authors.forename: Xing
authors.initials: X
authors.lastname: Yin
authors.forename: Alexander
authors.initials: A
authors.lastname: Balaeff
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Davis
authors.forename: Srinivas
authors.initials: S
authors.lastname: Rapireddy
authors.forename: Srinivas
authors.initials: S
authors.lastname: Reppireddy
authors.forename: Ravindra
authors.initials: R
authors.lastname: Venkatramani
authors.forename: Shahar
authors.initials: S
authors.lastname: Keinan
authors.forename: Danith H
authors.initials: DH
authors.lastname: Ly
authors.forename: Marcela
authors.initials: M
authors.lastname: Madrid
authors.forename: David N
authors.initials: DN
authors.lastname: Beratan
authors.forename: Catalina
authors.initials: C
authors.lastname: Achim
authors.forename: David H
authors.initials: DH
authors.lastname: Waldeck
mesh_terms: D004579:Electron Transport; D005998:Glycine / Q000031:analogs & derivatives / Q000737:chemistry*; D015394:Molecular Structure; D009696:Nucleic Acids / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*
chemical_list: D009696:Nucleic Acids; D010455:Peptides; D005998:Glycine