Study on the Interaction of Retinoic Acids to Human Serum Albumin by Fluorescence and Circular Dichroism Spectroscopy

Abstract

Retinoic acids (RAs) are considered to be endocrine disruptor chemicals and toxic environmental priority pollutants. In this paper, the interactions between RAs and human serum albumin (HSA) were examined by steady state fluorescence, time-resolved fluorescence and circular dichroism spectroscopy (CD). The RAs quenched the fluorescence of the protein remarkably and the mechanism of quenching was found to be static in nature. Synchronous fluorescence studies suggested that the polarity around the tryptophan(Trp) residues and tyrosine(Tyr) residues was not altered in the presence of RAs. The thermodynamic parameters of the binding reactions (ΔGθ, ΔHθ, ΔSθ) were measured,and they indicated the presences of hydrophobic forces and hydrogen interactions in the RAs–HSA interactions. The alterations of HSA secondary structure in the presence of RAs were confirmed by CD and time resolved fluorescence spectroscopy.