Figure 6.

General strategy for detecting protein sulfenic acids in cells. (a) Chemoselective reaction between 5,5-dimethyl-1,3-cyclohexanedione (dimedone, 1) and sulfenic acid. (b) Azide and alkyne-functionalized small-molecule probes for trapping and tagging protein sulfenic acids include DAz-2 (2) and DYn-2 (3). (c) Detection of protein sulfenic acids in living cells. Target cells are incubated with cell-permeable probes to trap and tag protein sulfenic acids in situ. After labeling, cell lysates are prepared and tagged proteins are bioorthogonally ligated to biotin or fluorescent reporter tags via click chemistry to enable detection by Western blot or in-gel fluorescence. Alternatively, biotinylated proteins can be enriched for proteomic analysis.