The NADPH-binding site of RrQR. a The NADPH molecule is represented by a stick model, and the NADPH omit FO-FC map contoured at 3.0 σ is shown in light blue. There is no cutoff of the radius of the atoms for the display of the electron density. b Side chains of the amino acid residues forming hydrogen bond(s) with the NADPH molecule are represented by a stick model, and the hydrogen bonds are shown by dotted lines. Residues G37 through G39 are also shown by a stick model.