Figure 3.

UDP-binding site and the omit difference electron-density map. The map has coefficients |F _o − F _c|, α_c and is contoured at 3.5σ. F _o represents the observed structure factors, F _c the calculated structure factors and α_c the calculated phases from which ligand contributions were omitted. Protein residues within 4 Å of UDP are labelled and putative hydrogen bonds (within 3.6 Å) are shown as black dashed lines. Atoms are coloured as described in Fig. 2 ▶, with the C^α atoms of the protein coloured salmon.