Influence of Taxifolin on the Human Serum Albumin-Propranolol Interaction: Multiple Spectroscopic and Chemometrics Investigations and Molecular Dynamics Simulation

The aim of the present study is to characterize the competition between propranolol (PROP) and taxifolin (TAX) in binding to human serum albumin (HSA) in a physiological buffer (pH 7.4) using multiple spectroscopic, chemometrics and molecular dynamics simulation measurements. Fluorescence analysis was used to determine the binding and quenching properties of HSA-ligand complexes in binary and ternary systems. These spectral data were further analyzed by the multivariate curve resolution-alternating least squares method. In addition, the concentration profiles and pure spectra of three species (HSA, ligand and HSA-ligand complex) and the apparent equilibrium constants K (app) were evaluated. Fluorescence spectroscopy showed that in the presence of TAX, the binding constant of HSA-PROP increased. The effect of ligands on the secondary structure of the protein has been analyzed by using Fourier transform infrared spectra. The conformational change of the protein was analyzed using synchronous fluorescence spectroscopy, three-dimensional fluorescence spectra and molecular dynamics (MD) simulation. The results of synchronous fluorescence and three-dimensional fluorescence spectra show that PROP alters the microenvironment around the tryptophan (Trp) and tyrosine (Tyr) residues in the presence of TAX. According to the MD simulation, these ligands can interact with the protein, affecting the secondary structure of HSA and modifying its tertiary structure. MD simulations and experimental data support each other.