Figure 5.

A potential mechanism for the production of cysteine persulfide (CysSSH) and GSH persulfide (GSSH) by 3‐mercaptopyruvate sulfurtransferase (MPST). (a) Hydrogen polysulfide (H₂S₂) produced by MPST reacts with cysteine and GSH to generate CysSSH and GSSH (Kimura et al., 2017; Nagahara et al., 2018). The observations that the endogenous concentrations of H₂S₂ are almost equivalent to those of hydrogen sulfide (H₂S) and that H₂S₂ and H₂S₃ produced by MPST readily react with cysteine and GSH to produce CysSSH and GSSH support this mechanism (Kimura et al., 2013; Kimura et al., 2015; Kimura et al., 2017; Koike et al., 2017; Nagahara, 2018; Nagahara et al., 2018). (b) Alternatively, MPST transfers sulfur to cysteine and GSH to generate CysSSH and GSSH without the involvement of H₂S₂ or H₂S₃. The figure is a reprint from Kimura et al. (2017)