Reactions of isolated persulfides provide insights into the interplay between H2S and persulfide reactivity

Abstract

Hydrogen sulfide is ubiquitous in biological systems and exerts function over a wide range of important physiological processes. Complementing free H2S, the reductant-labile sulfur pool plays significant roles in the translocation and action of sulfide, however the chemistry of reductant-labile sources of sulfide have not been studied systematically. Using a combination of NMR and UV-Vis spectroscopy, we investigated the spectroscopic properties and reactivity of three isolated organic persulfides and report a simple model for persulfide reactivity, including their roles as nucleophiles, electrophiles, and sulfide donors.

Acidity and nucleophilic reactivity of glutathione persulfide

“…The main difference in the energetics of the individual steps between thiol and persulfide was found in the homolytic S-H bond cleavage, which was ~20 % lower for MeSSH than for MeSH (Table S1). This is consistent with S-H bond dissociation energies reported for alkyl thiols and persulfides, that differed by 24 % (49), and with IR spectra, that showed shifted S-H stretching frequencies (50)(51)(52). The acidity of MeSSH was also estimated in the context of the proton-exchange method previously used to estimate the pKa of cysteine persulfide (3,53), yielding a ΔpKa of 1.7 with CCSD/6-31 G(d').…”

Speciation of reactive sulfur species and their reactions with alkylating agents: do we have any clue about what is present inside the cell?

“…Next, we compared the solution speciation observed in the UV–Vis spectra with the speciation of dibenzyl polysulfides (Bn 2 S X ) after quenching these solutions with the electrophile benzyl chloride (see Reaction 17) using 1 H‐NMR integration values of the benzyl proton resonances (see Table ). Benzyl chloride was used as a trapping agent due to the well‐characterized chemical shifts of the different benzyl polysulfide products and prior use to identify polysulfides (Ahrika et al ., ; Bailey and Pluth, ).…”

New Design of a Disulfurating Reagent: Facile and Straightforward Pathway to Unsymmetrical Disulfanes by Copper‐Catalyzed Oxidative Cross‐Coupling

“…Hydrodisulfide (RSSH), a key intermediate in the cell‐killing action of anticancer natural products leinamycin and varacin,– may serve as an ideal disulfane reagent. However, RSSH is a short half‐life time intermediate because of its high sensitivity and activity ,–. Based on our previous study, sulfide with a mask displayed unique properties in sulfur‐transfer reactions.…”