CPL - Chalmers Publication Library
| Utbildning | Forskning | Styrkeområden | Om Chalmers | In English In English Ej inloggad.

Lifetime Heterogeneity of DNA-Bound dppz Complexes Originates from Distinct Intercalation Geometries Determined by Complex-Complex Interactions

Johanna Andersson (Institutionen för kemi- och bioteknik, Fysikalisk kemi) ; Louise Fornander (Institutionen för kemi- och bioteknik, Fysikalisk kemi) ; Maria Abrahamsson (Institutionen för kemi- och bioteknik, Fysikalisk kemi) ; Eimer Tuite ; Pär Nordell (Institutionen för kemi- och bioteknik, Fysikalisk kemi) ; Per Lincoln (Institutionen för kemi- och bioteknik, Fysikalisk kemi)
Inorganic Chemistry (0020-1669). Vol. 52 (2013), 2, p. 1151-1159.
[Artikel, refereegranskad vetenskaplig]

Despite the extensive interest in structurally explaining the photophysics of DNA-bound [Ru(phen)(2)dppz](2+) and [Ru(bpy)(2)dppz](2+), the origin of the two distinct emission lifetimes of the pure enantiomers when intercalated into DNA has remained elusive. In this report, we have combined a photophysical characterization with a detailed isothermal titration calorimetry study to investigate the binding of the pure Delta and Lambda enantiomers of both complexes with [poly(dAdT)](2). We find that a binding model with two different binding geometries, proposed to be symmetric and canted intercalation from the minor groove, as recently reported in high-resolution X-ray structures, is required to appropriately explain the data. By assigning the long emission lifetime to the canted binding geometry, we can simultaneously fit both calorimetric data and the binding-density-dependent changes in the relative abundance of the two emission lifetimes using the same binding model. We find that all complex complex interactions are slightly unfavorable for Delta-[Ru(bpy)(2)dppz](2+), whereas interactions involving a complex canted away from a neighbor are favorable for the other three complexes. We also conclude that Delta-[Ru(bpy)(2)dppz](2+) preferably binds isolated, Delta-[Ru(phen)(2)dppz](2+) preferably binds as duplets of canted complexes, and that all complexes are reluctant to form longer consecutive sequences than triplets. We propose that this is due to an interplay of repulsive complex complex and attractive complex-DNA interactions modulated by allosteric DNA conformation changes that are largely affected by the nature of the ancillary ligands.

Nyckelord: one-dimensional lattice, light-switch, cooperative binding, minor-groove, dipyridophenazine complexes, ruthenium complexes, linear, dichroism, excited-state, ligands, d(gtcgac)(2)

Denna post skapades 2013-03-19.
CPL Pubid: 174827


Läs direkt!

Länk till annan sajt (kan kräva inloggning)

Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Fysikalisk kemi (2005-2014)



Chalmers infrastruktur