Persulfides and Their Reactions in Biological Contexts

Persulfides (RSSH/RSS – ) participate in sulfur trafficking, biosynthesis, and catabolism. In addition, they are proposed to be transducers of signaling effects of H 2 S, and to play protective roles against irreversible thiol (RSH) oxidation. The endogenous synthesis of persulfides is made at the expense of H 2 S, thiols and their oxidized derivatives. There are also exist formation pathways that do not involve H 2 S. Persulfides are acidic and at physiological pH the anionic form predominates. The chemistry of persulfides is complex, since they have strong nucleophilic character and, furthermore, the two sulfur atoms can constitute electrophilic centers. They are excellent one- and two-electron oxidants, and they can interact with metalloproteins. The increasingly recognized relevance of persulfides is leading to efforts to better understand these close relatives of thiols and H 2 S, and herein we describe the properties of persulfides in biological contexts.