Fig. 3. Native MS and SEC-SLS data of peroxiredoxin proteins in 100 mM ammonium acetate, pH 8.0. 20 μM of cleaved protein (A) and 20 μM His₆-tagged protein (C) in 100 mM ammonium acetate, pH 8.0. Mass spectra peaks were assigned charged states from 43+ to 46+. In both cases, the spectra demonstrate the proteins are dodecameric oligomers, with experimental MWs of 266 560 ± 68 Da and 305 045 ± 89 Da for cleaved and His₆-tagged variants respectively. The trap collision energy used to record both spectra was 20 V. SEC-SLS of 20 μM cleaved protein (B) and 20 μM His₆-tagged protein (D), both in 100 mM ammonium acetate, pH 8.0. The refractive index (black) and right-angle light scattering were used to calculate MWs (red) of particles in solution. The main protein peak is a dodecamer (∼266 kDa for cleaved and ∼300 kDa for tagged), which agree with the theoretical MW for each species (blue line).