Fig 2. Generation of SoxYZ-conjugated candidate Sox pathway intermediates.

SoxYZ was treated by the indicated protocols. The products were then analysed by ion exchange chromatography using a 1 mL MonoQ HR column (GE Healthcare) equilibrated in 30 mM Tris-HCl pH 8.0 (top of each panel). The fractions from the IEC separations that are indicated with arrows (A,B) or numbers (C,D) were analysed by ESI-MS and (for D only) by native PAGE (bottom of each panel). ESI-MS samples in (D) were treated with 20 mM iodoacetamide for one hour prior to analysis. The minor ESI-MS peaks marked with an asterisk (*) represent +15 Da adducts of the main peaks. Tetra-preIEC, Tetra-2, and Tetra-5 samples in (D) correspond to, respectively, the tetrathionate-treated SoxYZ before IEC and to the indicated fractions from the IEC separation.