Figure 5

Electron density, contoured at 2 sigma, for the DHO and ATC active sites in the mutant complex. (A) the “omit density” is shown for the substrate dihydroorotate (DOR, red mesh), the zinc atom (Znα, black mesh), the catalytic water molecule (Jα5 or in the text, HOH2018/A, red mesh) and the 2Fo-Fc electron density of residues within 4 Å of the substrate (blue mesh). Only side chains are shown except for residues P322, G323, V277, N278, and G154 which have main chain contacts with dihydroorotate (DOR425) atoms. Five other water molecules within 4 Å of DOR have been omitted for clarity. (B) The “omit density” for PALA (PAL, red mesh) in the ATC active site and the 2Fo-Fc electron density is shown for all ATC residues within 4 Å of the PALA molecule (blue mesh). Only side chains are shown except for residues P44-T48 and G251, which have main chain contacts with PALA atoms. P44 and its electron density, which overlay the inhibitor in this view, are shown at 50% transparency. Six water molecules within 4 Å of PALA have been omitted for clarity.