Biopolymers and cell. 2001; 17 (2): 169 - 177

Interaction of cyanine dyes with nucleic acids. 7. Carbocyanine dyes, substituted in polymethine chain, as possible probes for fluorescent nucleic acid detection

S. S. Lukashov, M. Yu. Losytskyy, Yu. L. Stominskii, S. M. Yarmoluk

To extend the application of carbocyanine dyes in fluorescent nucleic acid detection, the use of dyes substituted in a polymethine cliain is proposed. A series of thiacarbocyanine derivatives with alky I substituents in a polymethine chain have been synthesized, and the spectral luminescent properties of dyes in the presence of double-stranded DNA, RNA and bovine serum albumin (BSA) have been examined. The intrinsic fluorescence of all derivatives prepared is lower than that of unsubstituted thiacarbocyanine. The dyes show 1.75-76-fold fluorescence enhancement in the presence of nucleic acids. Lower enhancement (1.75-16.9 times) takes place in the presence of large excess of BSA. The highest fluorescence intensity for dye-nucleic acid complexes is observed for the i-methyl-substituted dye that is more than two times higher as compared to thiacarbocyanine. The substituents larger than methyl group disturb the planarity of thiacarbocyanine fluorophore excessively, and the fluorescence intensities of nucleic acid complexes of corresponding dyes are lower.