Figure 4.
Refined structures for the residues Ala40, Lys41, part of Arg39, and two discrete water molecules superimposed with the 5PTI structure, together with the σA-weighted electron density maps contoured at 2.3σ level. (A) Structure refined with QM (cyan) at w X-ray = 0.9; (B) structure refined with EH (magenta) at w X-ray = 0.9; (C) structure refined with QM (cyan) at w X-ray = 0.2; (D) structure refined with EH (magenta) at w X-ray = 0.2. All the aliphatic hydrogen atoms are omitted for clarity.