A combination of spectroscopic and molecular docking techniques to study interaction of bis(indolyl)methane with bovine milk α-casein

Spectroscopic and molecular docking techniques were used to study the interaction of bis(indolyl)methane (BIM), poorly soluble in aqueous solutions, with bovine -casein, as an efficient drug carrier. The results of Fourier transform infrared and circular dichroism spectroscopy demonstrated that -casein interacts with BIM molecule mainly via hydrophobic and hydrophilic interactions, resulting changes in the secondary structure of -casein. The fluorescence quenching measurements at 293-310 K revealed that the quenching mechanism was static, and the binding site of BIM to -casein was singular. Thermodynamic analysis, along with the negative value of http://www.w3.org/1999/xlink and positive value of, indicates that the hydrophobic interaction, hydrogen bonds, and van der Waals forces played major roles in the complex formation process. The distance between donor and acceptor, obtained according to fluorescence resonance energy transfer and docking studies, indicated that BIM induced a change from a hydrophobic environment around the Trp-193 of alpha-casein to an aqueous or hydrophilic environment.