Fig. 4.
Posttranslational modification of MT1X by electrophiles in NSOA. (A) Sketch map and sequence of MT1X with 20 cysteines coordinated with metals. The sequence of MT1X is provided. Only the peptide of β-domain (labeled in red) was detected. (B) Chromatogram of isotopically labeled peptide of MT1X peptide across seven treatments. Compared to control, the abundances of MT1X are lower in C1–5 exposures. (C) FC of MT1X in different NSOA treatment groups (n = 3). **P < 0.01; ***P < 0.001. (D) Reduction, alkylation, and MS detection of cysteine species with different modifications. Note that most cysteine modifications via ROS (e.g., S–S, S–OH) are reversible and should be detected by proteomics. The irreversible oxidation of cysteine to sulfonic acid (–SO3H) are also detectable by proteomics searching with variable modifications. Modifications by electrophiles (i.e., S–R) are irreversible and nondetectable by proteomics.