Two-Electron Reduction of Heme and Initiation of Heme Degradation

This is one possible psychedelic "loser" mechanism for the degradation of heme in association with the formation of a glutathionyl adduct. The "mechanism" is an adaptation, for better or worse, of the mechanisms proposed by these authors [Nakamura et al., 1984: (http://www.jbc.org/content/259/11/7080.full.pdf)(http://www.ncbi.nlm.nih.gov/pubmed/6725282); Atamna and Ginsburg, 1995: (http://www.jbc.org/cgi/content/full/270/42/24876); Schaefer et al., 1985: (http://www.ncbi.nlm.nih.gov/pubmed/3927975)], and the main interest I have is in keeping track of the two-electron reduction of heme. It's difficult to keep track of things. It seems more likely that a thioperoxyl derivative of glutathione, as discussed by Atamna and Ginsburg (1995), would initiate the degradation reactions, but thioperoxyl species mimic the actions of peroxides, etc., and doing those again could get repetitive. Schaefer et al. (1985) proposed that the reaction would repeat more than once and produce dipyrroles and maleimides (or, here, related sulfhydryl compounds or disulfide cross-links with amino acid residues on proteins, etc.):