Binding of methyl green to deoxyribonucleic acid analyzed by linear dichroism

Artikel i vetenskaplig tidskrift, 1977

From linear dichroism data a distinct structure of the strongest complex between the methyl green (MG) dication and the B-form DNA is concluded. MG is not intercalated but binds (probably to hydrophobic surfaces in the major groove) with its x and z axes at an angle to the local helix axis of 48° and 90°, respectively. At higher occupation density, exciton coupling between transition dipoles of adjacent molecules is visualized in the linear and circular dichroism spectra. The final spectra may be understood in terms of a right-handed (MG)N helix in the major groove of the double helix.