Investigation of the Key Heme in Cytchrome c3 to the Electron Pool Effect by Highly Sensitive EQCM Technique

Cytochrome c3, which has four bis-histidinyl coordinated hemes per molecule, is a redox protein, and stores electrons temporarily until recognizing a redox partner. This mechanism is called “electron pool effect”. In this study, highly sensitive EQCM measurement clarified which heme in cytochrome c3 caused the electron pool effect. To investigate the key heme to the electron pool effect, cytochrome c3 mutants in which the sixth axial ligand of one heme was changed were prepared, and the intermolecular electron transfer was measured by viologen-immobilized electrode. The kinetics of the electron transfer complex formation between cytochrome c3 and immobilized viologen indicated that redox of the heme II in cytochrome c3 caused the electron pool effect.