Reaction mechanism of tylosin tartrate with lysozyme

Under simulated physiological conditions, the interaction between tylosin tartrate and lysozyme was investigated at pH?=?7.40 by fluorescence spectroscopy. The results indicated that tylosin tartrate could strongly quench the intrinsic fluorescence of lysozyme. By determining the quenching constants of the reaction between tylosin tartrate and lysozyme at different temperatures, the quenching mechanism was proven to be a static quenching process. The thermodynamic parameters (ΔH°, ΔS°) of the reaction between tylosin tartrate and lysozyme were obtained by the Van’t Hoff equation, and were 27.80?kJ mol^?1 and 166.28?J mol^?1 K^?1, respectively. The results showed that hydrophobic interaction between tylosin tartrate and lysozyme was dominant. Synchronous fluorescence spectra revealed that the conformation of lysozyme was changed. This method could be applied to measure the content of tylosin tartrate.