Different Scenarios for Inter-Protein Electron Tunneling: The Effect of Water-Mediated Pathways

Recent theoretical developments now allow for reliable calculation oftunneling matrix elements in unimolecular biological electron transferreactions that have been tested experimentally. Most biological ETprocesses, however, are bimolecular, or involve large-scale proteindomain motions. In this paper, initial advances in this direction bystudying the inter-protein electron transfer between cytochrome c ₂andthe photosynthetic reaction center. Utilizing an approach that integratesmolecular dynamics and the Pathways method, we have observed that theensemble dominant tunneling pathways in this reaction go though thetyrosine 162 or are water mediated.