Title
Novel synthetic approach to asymmetric monocationic trimethine cyanine dyes derived from N-ethyl quinolinum moiety. Combined fluorescent and ICD probes for AT-DNA labelling
Author
Atanas Kurutos, Ivo Crnolatac, Iva Orehovec, Nikolai Gadjev, Ivo Piantanida, Todor Deligeorgiev
Year
2016
Journal
Journal of Luminescence
Abstract
Two asymmetric monocationic trimethine cyanine dyes were obtained via condensation reaction between 2-methylbenzothialolium salts containing various (aliphatic and benzyl) substituents on the nitrogen atom of the benzothiazolic chromophore, and 1-ethyl−4-(2-(phenylamine)vinyl)quinolin−1-ium iodide, by a novel improved method at room temperature under mild conditions. Both compounds bind non-covalently to double stranded DNA and RNA by micromolar affinity, but give highly selective fluorescent response>650 nm for only AT-DNA sequences at excess of DNA over dye, combined with equally AT-DNA selective ICD response at dye/DNA crowded conditions (r[dye]/ [AT-DNA]>0.2)-namely ICD bands (attributed to dye-dimer formation) allow determination of AT-DNA at submicromolar concentrations. Selectivity was attributed to particular steric properties of AT-DNA minor groove in respect to other studied ds-DNA/RNA. Comparison of aliphatic- and benzyl- dye showed that only aliphatic- derivative revealed ICD band upon binding to AU-RNA major groove and short AT-sequences in mixed sequence (ct-)DNA.
Instrument
J-810
Keywords
Circular dichroism, Ligand binding, Secondary structure, Organic chemistry