Elucidating the interaction of propofol and serum albumin by spectroscopic and docking methods

The interaction of human serum albumin (HSA) with propofol has been studied by fluorescence spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD) spectroscopy and docking methods. A gradual decrease in Stern-Volmer quenching constants with the increase in temperature showed the static mode of fluorescence quenching. The obtained binding constant (KA) was 8.18 × 105 M− 1. Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) changes were calculated, which revealed that the reaction is spontaneous, exothermic and hydrophobic force driven. FT-IR test revealed conformational changes of the protein and destruction of H-bonding upon interaction. Moreover, propofol induced a decrease in α-helical contents probably with increment of random coils or/and β-sheets of HSA, as observed from the far-UV CD spectra. Molecular docking and site probing study depicted that propofol fits into the hydrophobic pocket close to Sudlow site I in domain IIA of HSA. The present study will be helpful in understanding the binding mechanism of propofol and associated stability and conformational changes.