“…1,4,28,30,41 The paradigm of this tunable functionality in vivo is the interaction with cardiolipin (CL), a negatively charged glycerophospholipid found in the inner mitochondrial membrane (IMM), 30,40,42 which induces the cleavage of the Fe-S(Met80) bond, 1,5,9,19,21,28,30,32,39, imparting to cytc significant (lipo)peroxidase activity, which is crucial in triggering the apoptosis cascade. 1,5,28,30,40,47,73 In vitro, analogous heme axial ligand swapping from His/Met to His/His occurs upon chemical denaturation of both solution 14 and surface-immobilized yeast cytochrome c (ycc). 14,33,34,[74][75][76][77] Under the latter conditions, ycc gains remarkable pseudo-peroxidase activity.…”