Structural alteration of myoglobin with two homologous cationic surfactants and effect of β-cyclodextrin: multifaceted insight and molecular docking study
A detailed binding interactions of two homologous cationic surfactants (CTAB & CPC) with myoglobin (Mb) have been investigated employing various physicochemical and multifaceted techniques like tensiometry, UV-visible spectroscopy, steady-state fluorometry, time-resolved fluorometry, synchronous spectroscopy, circular dichroism (CD) spectroscopy, dynamic light scattering (DLS), stopped flow kinetics and cyclic voltammetry (CV) at the physiological pH at 298 K. The enthalpy changes for Mb-surfactant interactions have been investigated through isothermal titration calorimetry (ITC) study. Surfactant-Mb association kinetics has been examined by stopped flow technique. The drastic change in both cathodic and anodic peak current and secondary structural content of Mb even in the presence of low concentrations of CPC compared to CTAB reveals that CPC strongly interacts with Mb in contrast to CTAB. This clarifies the dominant role of head group of surfactant for the binding interactions with Mb. UV-visible and CD spectroscopy reveals that the recovery of the Soret band of Mb from structurally deformed Mb through the uses of β-CD. β-CD has also the ability to recover native conformation of Mb from unfolded one, which is confirmed by emission (steady state & time resolved) spectroscopy and DLS studies. Overall, the effect of β-CD on denatured Mb results recovery of its primitive conformation. The molecular docking study also unravels the potential role of head of surfactant on the binding interactions with Mb and the effect of β-CD.