Investigation of the interaction between chlorophenols and lysozyme in solution

The binding interactions of lysozyme with 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol were investigated by UV–vis absorption, CD, fluorescence, synchronous fluorescence, and three-dimensional fluorescence spectra techniques under physiological pH 7.40. The binding constants, quenching mechanism, and the number of binding sites were determined by the quenching of lysozyme fluorescence in presence of chlorophenols. H-bonds and hydrophobic interactions played major roles in stabilizing the chlorophenols–lysozyme complex. The distances r between chlorophenols and lysozyme were calculated to be 1.94 nm, 2.75 nm, 3.54 nm, and 3.76 nm for 2-CP, 2,4-DCP, 2,4,6-TCP, and PCP, respectively. The effects of chlorophenols on the conformation of lysozyme were analyzed using CD, synchronous fluorescence and three-dimensional fluorescence spectra.

► This is the first report on the interaction of chlorophenols with lysozyme by fluorescence spectra techniques. ► The number of –Cl partly effected the binding ability of chlorophenols with lysozyme. ► The H-bonds and hydrophobic interactions played major roles in stabilizing the chlorophenols–lysozyme complex. ► The calculated distance r of chlorophenols–lysozyme system may place chlorophenols at the interface of protein.