“…The fluorescence spectra were recorded at k exc = 280 nm and k emi from 290 to 500 nm. The intensity at 340 nm (tryptophan) was used to calculate the binding constant (K) according to previous literature reports (Bi et al, 2004;Dufour & Dangles, 2005;He et al, 2005;Tang, Qi, & Chen, 2005).…”