Spectroscopic studies of the multiple binding modes of a trimethine-bridged cyanine dye with DNA
ACS Citation
Sovenyhazy, K. M. Spectroscopic studies of the multiple binding modes of a trimethine-bridged cyanine dye with DNA. Nucleic Acids Res. 2003, 31, 2561-2569.
Version of Record
Abstract
The interaction between DNA and a benzothiazole-quinoline cyanine dye with a trimethine bridge (TO-PRO-3) results in the formation of three noncovalent complexes. Unbound TO-PRO-3 has an absorption maximum ({lambda}max) of 632 nm, while the bound dyes (with calf thymus DNA) have electronic transitions with {lambda}max = 514 nm (complex I), 584 nm (complex II) and 642 nm (complex III). The blue shifts in the electronic transitions and the bisignate shape of the circular dichroism bands indicate that TO-PRO-3 aggregates with DNA. Complex I has a high dye:base pair stoichiometry, which does not depend on base sequence or base modifications. The bound dyes exhibit strong interdye coupling, based on studies with a short oligonucleotide and on enhanced resonance scattering. From thermal dissociation studies, the complex is weakly associated with DNA. Studies with poly(dGdC)2 and poly(dIdC)2 and competitive binding with distamycin demonstrate that complex II is bound in the minor groove. This complex stabilizes the helix against dissociation. For complex III, the slightly red-shifted electronic transition and the stoichiometry are most consistent with intercalation. Using poly(dAdT)2, the complexes have the following dye mole fractions (Xdye): Xdye = 0.65 (complex I), 0.425 (complex II) and 0.34 (complex III).
Source Name
Nucleic Acids Research
Publication Date
1-1-2003
Volume
31
Issue
10
Document Type
Citation
Citation Type
Article