Mechanisms of myeloperoxidase catalyzed oxidation of H2S by H2O2 or O2 to produce potent protein Cys-polysulfide-inducing species

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

“…Inorganic polysulfide species have been suggested to be important mediators in biology (Greiner et al ., ; Kimura, ). They can be generated during mitochondrial oxidative catabolism (Powell and Somero, ; Bouillaud and Blachier, ; Jackson et al ., ; Modis et al ., ; Szabo et al ., ; Mishanina et al ., ), by metalloprotein‐catalysed oxidation of sulfide (Palinkas et al ., ; Bostelaar et al ., ; Padovani et al ., ; Garai et al ., ; Olson et al ., ; Vitvitsky et al ., ) or by reaction of sulfide with NO (Cortese‐Krott et al ., ). Although direct oxidation of sulfide by ROS is relatively slow in many cases (Carballal et al ., ), the neutrophilic oxidant, hypochlorous acid (HOCl), can oxidize sulfide with a nearly diffusion‐controlled rate to produce inorganic polysulfides, which could be a relevant route of polysulfide production under certain biological conditions (e.g.…”

Inorganic hydrogen polysulfides: chemistry, chemical biology and detection

“…Nagy et al . recently studied the detailed mechanisms of myeloperoxidase (MPO)‐catalysed H 2 S oxidation (Garai et al ., ) and found the Compound III state is formed in the reactions of H 2 S with MPO in the presence of oxygen. This enzymic reaction provides a slow flux of sulfane sulfur species generation (which likely involves H 2 S n ) that may be important in endogenous signalling.…”

Signalling by hydrogen sulfide and polysulfides via protein S‐sulfuration

“…Two cysteine residues Cys57 and Cys146, which form intramolecular disulfide bridge, are involved in the conformational stability of SOD, and Cys111 has a low pKa and is nucleophilic under physiological conditions (Olson et al, 2018). SOD also has a polysulfide bridge structure (Nielsen, Tachibana, Hansen, & Winther, 2011 (Garai et al, 2017;Nakamura, Nakamura, Yamazaki, & Morrison, 1984). Recently, it was reported that myeloperoxidase can even produce per or polysulfides even in the absence of H 2 O 2 by utilizing oxygen in collaboration with SOD (Garai et al, 2017).…”

“…SOD also has a polysulfide bridge structure (Nielsen, Tachibana, Hansen, & Winther, 2011 (Garai et al, 2017;Nakamura, Nakamura, Yamazaki, & Morrison, 1984). Recently, it was reported that myeloperoxidase can even produce per or polysulfides even in the absence of H 2 O 2 by utilizing oxygen in collaboration with SOD (Garai et al, 2017).…”