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Figure 4
The Fo − Fc electron-density map for a tryptophan ligand bound to anthranilate synthase (PDB code 1i1q ). (a) Prior to thinning, the full medial axis (cyan) is a wide flat shape inside the isosurface (blue mesh, contoured at the 3σ level). Both the full medial axis and individual medial axis segments are too complex for direct graph matching against ligand-coordinate graphs. After thinning the medial axis by using simplify from the Power Crust software package, the medial axis is converted to edges and vertices and thinned to obtain vertices (cyan) separated by approximately atom-to-atom distances. (b) The thinned medial axis (cyan) has many vertices near the atom positions from the best model (green). (c) The best model (green) aligns well with the deposited structure (gray). (d) The ARP/wARP model (magenta) also aligns well with the deposited structure (gray). |