Distant charge transport

Abstract

Highlighting this issue of PNAS is a special feature comprising a Perspective and five research articles on the theme of long-range electron transfer. Distant electron transfers play key roles in aerobic respiration and photosynthesis, which work in concert: The oxygen that is evolved by photosynthetic organisms is the oxidant that sustains life in aerobic microbes and animals; and, in turn, the end products of aerobic respiratory metabolism, carbon dioxide and water, nourish photosynthetic organisms. Electron flow through proteins and protein assemblies in the respiratory and photosynthetic machinery commonly occurs between redox active cofactors that are separated by large molecular distances, often on the order of 10–25 Å. Although these cofactors are weakly coupled electronically, the reactions are remarkably rapid and specific. Understanding the underlying physics and chemistry of these distant electron transfer processes has been an overarching goal of theorists and experimentalists for many years.