Fast photochemical oxidation of proteins for comparing solvent-accessibility changes accompanying protein folding: Data processing and application to barstar

► Protein footprinting informs protein folding at peptide and amino-acid levels. ► Radicals from fast photochemical oxidation of proteins footprint on μs timescale. ► FPOP of unfolded and folded barstar distinguishes residues involved in folding. ► Residues that change as folding occurs are hydrophobic and reactive in FPOP. ► Processing of FPOP data can utilize software common to proteomics laboratories.