 | Acta Crystallographica Section D Acta Crystallographica Section D BIOLOGICAL CRYSTALLOGRAPHY |
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![[Figure 2]](fw5082fig2mag.jpg)
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Figure 2
Omit electron-density maps. (a) Stereoview of portions of β-strands a (29–32) and b (37–41) superimposed on the difference map computed at the final stages of refinement by omitting these residues. The map is contoured at the 3.5σ level. (b) A short stretch of an omit map for residues 62–64. The left panel shows electron density contoured at the 10σ level. Blobs of electron density correspond to the atomic positions, a feature seen in high-resolution refinement. A sausage-shaped density at the same contour level is seen at the peptide linkage indicated by an arrow. This feature was seen at almost all of the peptide bonds in the molecule. The right panel shows the same segment contoured at a slightly lower level (7σ). Here, the boundaries of the residues are seen with a conspicuous hole in the middle of the pentagonal rings (His62 and Pro63), a feature normally observed in atomic resolution structures. (c) The side chain of residue Gln67 exhibits dual conformation as shown. The Gln67 residue is superimposed on the omit map (contour level of 3σ) calculated without its coordinates. The backbone atoms are seen at the 9σ level, whereas the side chain is only seen at about the 3σ level. The two conformations for the tip of the side chain (Cγ, Cδ, O∊1, and N∊2 atoms) designated as A and B, are shown in cyan and red. Figs. 2 and 3 were produced using O. |
![[Figure 2]](fw5082fig2.jpg)
| BIOLOGICAL CRYSTALLOGRAPHY |
ISSN: 1399-0047
