2.3.2. Fluorescence spectroscopy
Fluorescence steady state measurements were performed on a spectrofluorimeter (FS920 Edinburgh Instruments, UK). Scanning parameters, for all measurements, were optimised with slit width 10.0 nm for excitation and emission. The concentration of the samples was 0.5 mg/ml. The excitation wavelength was set at 295 nm to selectively excite the tryptophan residues. The emission spectra were recorded in the wavelength range of 300–360 nm (Rawel et al., 2000 and Zhang et al., 2012).