Figure 6. Fluorescence emission spectra of ANS bound to intact hSOD1 (holo-SOD1) and Zn-depleted hSOD1.

Either holo- or Zn-depleted SOD1 (5 μM) in 10 mM Tris/acetate, pH 7.0, was incubated with 10 μM ANS (20 min at 23 °C). Excitation wavelength was 372 nm. Background fluorescence (absence of protein) was subtracted from spectra. a.u., arbitrary units.