Probing structure of blood plasma proteins with solvatochromic fluorescent probes based on Nile red and its derivatives

摘要

Abstract: Uncharged long-wave fluorescent probes, Nile red and its derivatives varying in lipophilicity, were used for probing hydrophobic binding sites of human serum albumin (HSA) and lipoproteins (LP) in norm and pathology. The synchro-scan fluorescence spectra (synchronous scanning of both excitation and emission wavelengths at constant $Delta$lambda@) of the probes were studied in HSA solutions and in whole blood plasma. The parameters of the spectra were sensitive to pH-induced conformational N$YLD@B transition in HSA. In blood plasma, each of the probes displayed a two-component synchro-scan spectrum revealing two pools of the dye bound to HSA (longer wavelength) and LP (shorter wavelength). The probe distribution between LP and HSA was also sensitive to N$YLD@B transition. The LP/HSA probe distribution ratio was shown to increase significantly in certain pathologies, due to either hypoalbuminemia or lowered ligand-binding capacity of HSA. Also, spectral shifts were observed in the band of albumin-bound probe. The determination of the distribution parameter may be proposed as an informative and feasible diagnostic test.!27