Figure 5. Fluorescence spectra of WT αB-crystallin and its mutants following ANS binding. Spectra were recorded by excitation at 390 nm and emission from 400 to 600 nm using 0.2 mg/ml protein preparations mixed with 15 μl of 0.8 mM ANS (dissolved in methanol) and incubated at 37 °C for 15 min. A: WT αB-crystallin and its deamidated and NH₂-terminal domain deleted mutants. B: WT αB-crystallin and its deamidated and COOH-terminal extension deleted mutants. The dotted lines indicated the wavelength of maximum peak fluorescence (λ_max) observed in WT αB-crystallin, used to determine whether a blue or a red shift in wavelength occurred.