FIGURE 5.

In the presence of l-Met-SO, Cd-MsrA is mycothiolated on all three catalytic Cys residues. Identification of S-mycothiolation on Cys²⁰⁶ is shown. The multistage activation LC-MSⁿ spectrum shows MS² data obtained from a +2 parent ion with m/z 1314.8 combined with MS³ data obtained from a daughter ion of m/z 1224.8 resulting from a neutral loss of inositol (180 Da). The y- and b-series of ions allow exact localization of the mixed disulfide between mycothiol and the Cys residue. &, daughter ions obtained after the neutral loss.