Electron Spin Resonance Spectroscopy of the Cytochrome bc1 Complex: The Chemistry of Biology

Abstract: The Cytochrome (cyt) bc1 complex is a large complex of protein embedded in the cellular membrane. Its function is to couple the flow of electrons in the biological electron transport chain to the pumping of protons across a membrane for use in generating ATP. Cyt bc1 uses a number of strategies to control the flow of electrons from a two-electron carrier like quinol to a one-electron carrier like a heme. These include: large changes in protein conformation; tunneling of electrons; changes in redox potential with protein conformation; and proton-gated electron transfer all of which can be studied by the use of electron spin resonance in all its forms.