Figure 1.

(a) Proposed mechanism of the tag-switch technique for the detection of nitrosothiol modification in proteins. (b–d) Proposed mechanisms of tag-switch techniques for the detection of cysteine per/polysulfides in proteins. The target persulfide groups are switched to biotin-linked modifications derived from (b) biotin-HPDP and (c) IAP-biotin for further analyses. (d) To isolate persulfurized proteins, the biotin-linked disulfides derived from IAP-biotin can be selectively reduced by DTT and eluted from the streptavidin-coated magnetic beads. (e) CN-biotin can also be used to switch the target persulfide groups to biotin-linked modifications for further analyses.