1 research outputs found
Harnessing Redox Cross-Reactivity To Profile Distinct Cysteine Modifications
Cysteine <i>S</i>-nitrosation
and <i>S</i>-sulfination
are naturally occurring post-translational modifications (PTMs) on
proteins induced by physiological signals and redox stress. Here we
demonstrate that sulfinic acids and nitrosothiols react to form a
stable thiosulfonate bond, and leverage this reactivity using sulfinate-linked
probes to enrich and annotate hundreds of endogenous <i>S</i>-nitrosated proteins. In physiological buffers, sulfinic acids do
not react with iodoacetamide or disulfides, enabling selective alkylation
of free thiols and site-specific analysis of <i>S</i>-nitrosation.
In parallel, <i>S</i>-nitrosothiol-linked probes enable
enrichment and detection of endogenous <i>S</i>-sulfinated
proteins, confirming that a single sulfinic acid can react with a
nitrosothiol to form a thiosulfonate linkage. Using this approach,
we find that hydrogen peroxide addition increases <i>S</i>-sulfination of human DJ-1 (PARK7) at Cys106, whereas Cys46 and Cys53
are fully oxidized to sulfonic acids. Comparative gel-based analysis
of different mouse tissues reveals distinct profiles for both <i>S</i>-nitrosation and <i>S</i>-sulfination. Quantitative
proteomic analysis demonstrates that both <i>S</i>-nitrosation
and <i>S</i>-sulfination are widespread, yet exhibit enhanced
occupancy on select proteins, including thioredoxin, peroxiredoxins,
and other validated redox active proteins. Overall, we present a direct,
bidirectional method to profile select redox cysteine modifications
based on the unique nucleophilicity of sulfinic acids