Fig. 2

The structure of the NADH-binding site of complex I. a Enlarged stereo view into the NADH-binding pocket in the reduced state of the protein and bound NADH (carbon in black). b The structure of oxidized NuoEF with bound NAD⁺, c the structure of reduced NuoEF with bound NADH and (d) overlay of the structures of oxidized and reduced NuoEF in the absence of pyrimidine nucleotides. The flipping peptide bond is highlighted in yellow and hydrogen-bonding interactions are indicated by dashed lines. The C = O group of the peptide bond between E95^F and S96^F points toward the FMN in the oxidized state of the protein with and without bound NAD⁺ and flipped away in the reduced state of the protein with and without NADH