Figure 7.

Detection of oxidized polysulfur structure of Na₂S-treated YgaV by iCOPS method: (A) The complex of ILC³¹ML (blue) and KNVYC⁹⁸P (red) with an intra-tetrasulfide bridge was detected under low voltage ionization conditions (30 V), while the oxidized polysulfur bond was disrupted by high voltage ionization (60 V), resulting in the formation of free KNVYC⁹⁸P peptide which was detected at the same retention time as the intact peptide complex (dashed line); (B) Various lengths of oxidized polysulfur bridges between ILC³¹ML and KNVYC⁹⁸P peptides were investigated under low-voltage ionization conditions (30 V). A significant signal of the intra-tetrasulfide bridge-containing complex was only detected (red arrow).