Figure 1. Methionine metabolism, adapted from [15]. Abbreviations are listed alphabetically. ATP: adenosine triphosphate; B6: pyridoxyldependant enzymes; B12: cyanocobalamin; CYP: cytochromes P450; iSO4: inorganic sulphate; glu-6-PO4: glucose-6-phosphate; GSH: glutathione; GSH-GST: the glutathione-glutathione transferase couple; GSH.Px: selenoenzyme glutathione peroxidase; GSH.Rx: riboflavin-dependant glutathione reductase that interlinks with shuttles involving glucose-6-phosphate (glu-6-PO4) and nicotine adenosine phosphate in oxidized (NADP) or reduced (NADPH) form; GSSG: reversibly oxidized form of glutathione; GSSR: irreversibly oxidized form of glutathione that is excreted from the cell; MTA: methyl thioadenosine; Pi: activated phosphate; RXS: reactive xenobiotic species; SAH: sulph-adenosylhomocysteine; SAMe: sulph-adenosylmethionine.