The electron density of Asp65, Val212 and Gln220 of molecule A. This map (2Fo-Fc composite omit map) is contoured at 1σ. Hydrogen bonds are denoted by dashed lines with numbers denoting the respective distances in the unit of Å. (a) shows that Asp65 of molecule A has hydrogen bond interaction with Thr67 and salt bridge with Arg46 besides interaction with water molecules S244 and S265. (b) shows that Val212 of molecule A resides in a hydrophobic environment. (c) shows that Gln220 of molecule A has no interaction with other residues except the hydrogen bond with the symmetry related water molecule S327.