Exploring structural change of protein bovine serum albumin by external perturbation using extrinsic fluorescence probe: spectroscopic measurement, molecular docking and molecular dynamics simulation

Abstract

Structural modification through binding interaction of plasma protein bovine serum albumin (BSA) with an extrinsic charge transfer fluorophore 5-(4-dimethylamino-phenyl)-penta-2,4-dienoic acid (DMAPPDA) and its response to external perturbation due to interactions with surfactant sodium dodecyl sulphate (SDS) have been explored at physiological pH by steady state absorption, emission, fluorescence anisotropy, red edge excitation shift, far-UV circular dichroism and time resolved spectral measurements in combination with Molecular Docking and Molecular Dynamics (MD) simulation. Interaction of the probe with BSA is reflected by a small change in protein secondary structure with fluorescence enhancement and blue shift of probe emission. Molecular docking studies revealed that the probe binds to the hydrophobic cavity of sub-domain IIA of BSA. The distance for energy transfer from the tryptophan of BSA to the bound DMAPPDA measured by Fluorescence Resonance Energy Transfer is in good agreement with the molecular docking results. MD simulation predicts stabilization of the complex with respect to the bare molecule. Interaction of BSA and SDS with DMAPPDA supports the movement of the probe from hydrophilic free water region to a more restricted hydrophobic zone inside the protein.