The binding of novel two-color fluorescence probe FA to serum albumins of different species.

The novel two-color ratiometric fluorescence probe FA belonging to a class of 3-hydroxychromone dyes was applied for characterization of binding sites in serum albumins obtained from seven species (bovine, dog, horse, human, pig, rabbit and sheep). On strong and highly specific FA binding to the same location in protein structure, the species-dependent differences were observed in positions of absorption maxima, positions of two fluorescence emission bands and the intensity ratios between them. They were analyzed by multiparametric algorithm that allowed a detailed characterization of probe-binding sites and were characterized by very low polarity, high electronic polarizability and different extent of intermolecular hydrogen bonding. The species-dependent differences were also observed in time-resolved fluorescence emission decays. Fluorescence competition experiments with the drug warfarin, suggested the location of FA binding site within or in proximity to Domain IIA.