Protein photodegradation in the fluorescence unfolding kinetics study of bromelain

Abstract: We have detected protein photodegradation in the fluorescence unfolding kinetics experiment of stem bromelain, a cysteine proteinase from the papain family. Thermally induced unfolding has been followed by near and far circular dichroism and tryptophan fluorescence emission. It was found that the fluorescence kinetics involves two phases. This biphasic nature results from ultraviolet induced photolysis oftryptophan.