Figure 2. Spectral properties of FXN wild type and variants.

(A) Near-UV CD spectra were recorded in a 1.0-cm quartz cuvette at 1.1–1.2 mg/mL protein concentration. (B) Intrinsic fluorescence emission spectra were recorded at 60–80 μg/mL variants (0.09 AU_280nm, 295 nm excitation wavelength). (C) Far-UV CD spectra were recorded in a 0.1-cm quartz cuvette at 103–130 μg/mL. All spectroscopic measurements were carried out at 20°C in 20 mM Tris-HCl, pH 8.0 containing 0.1 M NaCl and 0.2 mM DTT.