Fluorescence emission spectra were recorded on a FLUORMAX-4 fluorescence spectrophotometer (HORIBA, USA) at 25
◦C in a 1-cm
cell. Protein concentration was 50g/mL in 5 mM sodium acetate
buffer (pH 5.0). Samples were excited at 280 nm, and the emission
spectra were recorded at 300–400 nm. The scanning experiments
were performed in triplicate, and the processed data represented
the mean of the three measurements.