The interaction mechanism between anionic or cationic surfactant with HSA by using spectroscopy, calorimetry and molecular docking methods

Abstract

Sodium dodecyl sulfate (SDS) and cetyl trimethylammonium bromide (CTAB) are common ionic surfactants. Former researches have investigated the interactions between the two surfactants and human serum albumin (HSA), separately. However, they only used limited methods to investigate the toxicity between the surfactants and HSA, and did not compare the toxicological effects between different types of surfactants. For full evaluating the mechanism of surfactants with HSA and comparing the difference between two kinds of surfactants, the methods of spectroscopy, molecular modeling calculation, and calorimetry were used in this paper. With the addition of CTAB, the secondary structure of HSA was unfolded. While, SDS did not cause clearly changes of the protein skeleton. Based on the ITC results, SDS could bind to HSA through an exothermic process and CTAB could bind to HSA through an endothermic process. According to the results of molecular docking study, SDS bound to HSA with Arg 410 and Tyr 411 residues through electrostatic force, while CTAB interacted with HSA with a weak electrostatic force. Thus the decrease of esterase activity of HSA with the addition of SDS was sharper than those with the addition of CTAB.