Domain-Specific Association of a Phenanthrene–Pyrene-Based Synthetic Fluorescent Probe withBovine Serum Albumin: Spectroscopic and Molecular Docking Analysis

摘要

In this report, the interaction between a phenanthrene–pyrene-based fluorescent probe (PPI) and bovine serum albumin (BSA), a transport protein, has been explored by steady-state emission spectroscopy, fluorescence anisotropy, far-ultraviolet circular dichroism (CD), time-resolved spectral measurements, and molecular docking simulation study. The blue shift along with emission enhancement indicates the interaction between PPI and BSA. The binding of the probe causes quenching of BSA fluorescence through both static and dynamic quenching mechanisms, revealing a 1:1 interaction, as delineated from Benesi–Hildebrand plot, with a binding constant of ∼10⁵ M^–1, which is in excellent agreement with the binding constant extracted from fluorescence anisotropy measurements. The thermodynamic parameters, ΔH°, ΔS°, and ΔG°, as determined from van’t Hoff relationship indicate the predominance of van der Waals/extensive hydrogen-bonding interactions for the binding phenomenon. The molecular docking and site-selective binding studies reveal the predominantbinding of PPI in subdomain IIA of BSA. From the fluorescence resonanceenergy transfer study, the average distance between tryptophan 213of the BSA donor and the PPI acceptor is found to be 3.04 nm. CD studydemonstrates the reduction of α-helical content of BSA proteinon binding with PPI, clearly indicating the change of conformationof BSA.