Characterization of the reaction products of cytochrome c with glutathione by mass spectrometry

Cytochrome c and glutathione (GSH) are two important biomolecules that regulate many cellular processes. The reaction of cytochrome c with GSH involves radical oxygen species and exhibits significant complexity. In the present work, the reaction of cytochrome c with GSH in water was characterized using mass spectrometry. The results show for the first time that the reaction generates multiple products including apocytochrome c in oxidized and reduced forms, glutathionylated apocytochrome c, GSH-modified cytochrome c, and oxidized and hydroxylated species. The reaction is O2 dependent and is rapid in water at neutral pH and 37 °C. The reaction involves the cleavage of thioether linkages between the heme and apocytochrome c. Evidence for the role of H2O2 and other oxygen radicals in this reaction is also provided.