Electron Bifurcation

Electron bifurcation is a newly discovered catalytic process that involves combining exergonic and endergonic electron transfer reactions for the efficient coupling of electrochemical potential to chemical bond formation. Electron bifurcation has been discovered in several different types of a biochemical reaction but the catalytic mechanism is poorly understood. The main requirements for a catalyst to bifurcate electrons are 1) a redox center that is capable of performing both one and two electron redox reactions / electron transfer reactions and 2) an effective gating mechanism to ensure that electrons are diverted to the path of the endergonic electron transfer as well as to the exergonic reaction. These features are being delineated in three electron bifurcating enzymes that catalyze different reactions 1) coupling of electrons from ferredoxin and pyridine nucleotides in the production of hydrogen gas 2) the ferredoxin-based low potential electron driven interconversion between different pyridine nucleotide-based electron carriers and 3) the coupling of the pyridine nucleotide-based oxidation to the reduction of quinone and to the reduction of the low potential electron carrier ferredoxin. Key technical approaches and capabilities in this thrust include 1) enzyme kinetics, 2) informatics, 3) paramagnetic and optical spectroscopy, electron transfer network analysis, 4) mass spectrometry, and 5) x-ray crystallography.