Fluorescence studies of thermal stability of staphylococcal exfoliative toxins A and B

Abstract The quantum yields of intrinsic fluorescence of staphylococcal exfoliative toxins ETA and ETB were determined after excitation at 295 nm and 275 nm respectively. The variations in the intrinsic fluorescence and degree of fluorescence polarization showed conformational modifications of ETA around 57–59°C and of ETB around 52–54°C. Above these transition temperatures, ETB precipitated out and its biological activity was lost, whereas ETA showed almost no precipitation and no change in its biological activity, despite the structural changes in the molecule.