title: Electron-hole transfer in G-quadruplexes with different tetrad stacking geometries: a combined QM and MD study.
abstract: G-quadruplex nucleic acids represent a unique avenue for the building of electrically conductive wires. These four-stranded structures are formed through the stacking of multiple planar guanine assemblies termed G-tetrads. The diverse folding patterns of G-quadruplexes allow for several geometries to be adopted by stacked guanine bases within the core and at the dimeric interface of these structures. It is currently not clear how different G-tetrad stacking arrangements affect electron hole mobility through a G-quadruplex wire. Using a combined quantum mechanics and molecular dynamics approach, we demonstrate that the electron-hole transfer rates within the G-tetrad stacks vary greatly for different stacking geometries. We identify a distinguished structure that allows for strong electronic coupling and thus enhanced molecular electric conductance. We also demonstrate the importance of sampling a large number of geometries when considering the bulk properties of such systems. Hole hopping within single G-tetrads is slower by at least two orders of magnitude than between stacked guanines; therefore, hole jumping within individual tetrads should not affect the hole mobility in G-quadruplexes. The results of this study suggest engineering G-tetrads with continuous 5/6-ring stacking from an assembly of single guanosine analogs or through modification of the backbone in G-rich DNA sequences.
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Lech
authors.forename: Anh Tuân
authors.initials: AT
authors.lastname: Phan
authors.forename: Maria-Elisabeth
authors.initials: ME
authors.lastname: Michel-Beyerle
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Voityuk
mesh_terms: D004579:Electron Transport; D004583:Electrons; D054856:G-Quadruplexes; D056004:Molecular Dynamics Simulation; D009690:Nucleic Acid Conformation; D011789:Quantum Theory