Binding of cationic Cm-E2O-Cm gemini surfactants with human serum albumin and the role of β-cyclodextrin

Abstract

The non-covalent interaction of human serum albumin (HSA) with cationic Cm-E2O-Cm gemini surfactants has been investigated employing a host of techniques. The fluorescence emission experiments reveal remarkable blue shifts after addition of the geminis. Pyrene micropolarity data are indicative of steep decrease in polarity sensed by the probe which, in turn, point towards the closeness of hydrophobic moieties of Cm-E2O-Cm and the serum albumin. UV absorbance of HSA increased with sequential addition of each gemini surfactant. CD spectral readings indicate significant unfolding of α-helices. Molecular docking studies predict a spontaneous binding between the geminis and the serum albumin. When all the above mentioned studies were carried out in the presence of 1.679 mM of β-cyclodextrin (β-CD), significant alteration in the results was obtained. The blue shifts in the fluorescence emission spectra were reduced. The polarity curves were less steep and the UV absorbance values were modified. The α-helical content of HSA was also influenced. These changes are ascribed to the interaction of β-CD and Cm-E2O-Cm gemini surfactants which has influence on their interaction with HSA. This is in conformity with the molecular docking results where hydrogen bonding between β-CD and Cm-E2O-Cm gemini surfactants was found to be a significant possibility.