Near‐Atomic Resolution Neutron Crystallography on Perdeuterated Pyrococcus furiosus Rubredoxin: Implication of Hydronium Ions and Protonation State Equilibria in Redox Changes

Neutron crystallographic analyses at near-atomic resolution are presented for both reduced and oxidized forms of perdeuterated Pyrococcus furiosus rubredoxin, a small iron–sulfur redox protein with remarkable thermostability. Hydronium ions may play a key role in the protonation and charge-transfer processes associated with the oxidized and reduced forms of the protein. Picture: overall structure showing D3O+ ions (red and gray molecules).