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    • Keywords


      Polymethine (cyanine) dyes; serum albumins; complexation; cis–trans equilibrium; spectralfluorescent probes; fluorescence growth.

    • Abstract


      The absorption and fluorescence spectral properties of three meso-substituted hydrophilic thiacarbocyanine dyes were studied in solutions and in noncovalent complexes with human and bovine serum albumins (HSA and BSA, respectively). The presence of alkyl substituents at the meso-position of the polymethine chain of the dyes determines the occurrence of a cis–trans equilibrium. Dyes form aggregates in aqueous media; the effect of electrolyte (NaCl) on aggregation has been studied. The interaction of the dyes with albumins leads to the decomposition of the aggregates and is accompanied by a shift in the isomericequilibrium. Complexation with HSA leads to accumulation of dye monomers in the trans-form. However, in the case of BSA the cis-to-trans isomeric shift is incomplete. Using the fluorescence data, the effective binding constants of the trans-isomers with albumins (Ka) and the detection limits of albumin molecules (LD and LQ) were determined. The data obtained are indicative of high selectivity of some dyes to HSA compared to BSA. The results of molecular docking experiments correspond to the data obtained from the spectra. The influence of the dyes on intrinsic fluorescence of HSA and BSA was also studied, and fluorescence quenching, static in nature, was detected.

    • Author Affiliations



      1. N. M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Kosygin St. 4, Moscow 119334, Russia
    • Dates

  • Journal of Chemical Sciences | News

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