title: π-Stacking effects on the EPR parameters of a prototypical DNA spin label.
abstract: The character and value of spin labels for probing environments like double-stranded DNA depend on the degree of change in the spin Hamiltonian parameters of the spin label induced by the environment. Herein we provide a systematic theoretical investigation of this issue, based on a density functional theory method applied to a spin labeled DNA model system, focusing on the dependence of the EPR properties of the spin label on the π stacking and hydrogen bonding that occur upon incorporating the spin label into the selected base pair inside DNA. It is found that the EPR spin Hamiltonian parameters of the spin label are only negligibly affected by its incorporation into DNA, when compared to its free form. This result gives a theoretical ground for the common empirical assumption regarding the behaviour of spin Hamiltonian parameters made in EPR based measurements of the distance between spin labels incorporated into DNA.
authors.affiliation: KTH Royal Institute of Technology, School of Biotechnology, Division of Theoretical Chemistry & Biology, SE-106 91 Stockholm, Sweden. B.F.bogdanf@theochem.kth.se
authors.forename: Bogdan
authors.initials: B
authors.lastname: Frecus
authors.forename: Zilvinas
authors.initials: Z
authors.lastname: Rinkevicius
authors.forename: Hans
authors.initials: H
authors.lastname: Ågren
mesh_terms: D004247:DNA / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D006860:Hydrogen Bonding; D013113:Spin Labels
chemical_list: D013113:Spin Labels; D004247:DNA