Investigation on the interaction of cefpiromesulfate with lysozyme by fluorescence quenching spectroscopy and synchronous fluorescence spectroscopy

The reaction mechanism of cefpiromesulfate with lysozyme at different temperatures (298, 310 and 318K) was investigated using fluorescence quenching and synchronous fluorescence spectroscopy under simulated physiological conditions. The results clearly demonstrated that cefpiromesulfate caused strong quenching of the fluorescence of lysozyme by a static quenching mechanism. The binding constants obtained using the above methods were of the same order of magnitude and very similar. Static electric forces played a key role in the interaction between cefpirome sulfate and lysozyme, and the number of binding sites in the interaction was close to 1. The values of Hill's coefficients were >1, indicating that drugs or proteins showed a very weakly positive cooperativity in the system. In addition, the conclusions obtained from the two methods using the same equation were consistent. The results indicated that synchronous fluorescence spectrometry could be used to study the binding mechanism between drug and protein, and was a useful supplement to the fluorescence quenching method. In addition, the effect of cefpirome sulfate on the secondary structure of lysozyme was analyzed using circular dichroism spectroscopy. Copyright (c) 2015 John Wiley & Sons, Ltd.