Peptide-Mediated Intramolecular Electron Transfer: Long-Range Distance Dependence

Electron transfer is one of the fundamental reactions in biological photosynthesis, respiration, and redox-mediated enzyme catalysis. Understanding the role of peptides and proteins in mediating long-range electron transfer has important physical, chemical, and biological implications.
Intramolecular electron-transfer reactions, where electron transfer occurs between donor and acceptor sites separated by a synthetic peptide or protein fragment, have so far provided the most insight into the role of the peptide and protein in mediating electron transfer. This article reviews the work the authors' group and others on small molecule systems that have been designed and studied to explore long-range electron-transfer pathways available between a donor and an acceptor separated by a rigid peptide framework. The role of the secondary structure of polyproline II in facilitating these mediations is explored.