Fig. 3.

The nitrate-binding cavity. (A) Representative electron density of nitrate and coordinating residues. The map shown was calculated with the coefficients (2F_o − F_c), where F_o is the experimentally observed structure factor amplitude and F_c is the calculated structure factor amplitude from the model. For the sake of clarity, G240 was omitted. (B) Schematic representation of the nitrate-binding site. Shown here are the protein–ligand interactions between NrtA and nitrate with all potential hydrogen-bonding and electrostatic interactions depicted as dashed lines.