Complex I plays a central role in cellular energy production, coupling electron transfer
between NADH and quinone to proton translocation. The mechanism of this highly efficient
enzyme is currently unknown. Mitochondrial complex I is a major source of reactive oxygen
species, which may be one of the causes of aging. Dysfunction of complex I is implicated in
many human neurodegenerative diseases. We have determined several x-ray structures of
the oxidized and reduced hydrophilic domain of complex I from Thermus thermophilus at up …