Signaling by HS is proposed to occur via persulfidation, a posttranslational modification of cysteine residues (RSH) to persulfides (RSSH). Persulfidation provides a framework for understanding the physiological and pharmacological effects of HS. Due to the inherent instability of persulfides, their chemistry is understudied. In this review, we discuss the biologically relevant chemistry of HS and the enzymatic routes for its production and oxidation. We cover the chemical biology of persulfides and the chemical probes for detecting them. We conclude by discussing the roles ascribed to protein persulfidation in cell signaling pathways.

Highlights d Dimedone Switch method is a versatile, chemoselective persulfide labeling approach d Protein persulfidation is an evolutionarily conserved modification of cysteine thiols d Persulfidation waves rescue cysteines from overoxidation caused by ROS d Persulfidation decreases with aging, increases with caloric restriction, and extends lifespan