Investigation on the interaction of cefonicid sodium with lysozyme by fluorescence quenching spectroscopy

Author(s): Rong Han, Baosheng Liu, Gaixia Li, Qiuju Zhang

Under simulative physiological conditions, the interaction between lysozyme (LYSO) and cefonicid sodium (CID) was investigated using fluorescence quenching and synchronous fluorescence spectroscopy at different temperatures (298, 310 and 318K). The results indicated that CID could quench the intrinsic fluorescence of LYSO strongly,and the quenching mechanism was a static quenching process. The order of magnitude of binding constants (Ka) was 104, the number of binding site (n) in the binary systemwas approximately equa to 1. The negative enthalpy changes and positive entropy changes implied that electrostatic interaction might play a main role in the interaction between CID and LYSO. The values of Hill’s coefficients were more than 1ÿit indicated that drugs or proteins had a very weakly positive cooperativity in the system. Studies on the interaction between LYSO and drug will facilitate interpretation of the drug’s metabolism and transporting process in the blood.

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