 | Acta Crystallographica Section D Acta Crystallographica Section D BIOLOGICAL CRYSTALLOGRAPHY |
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![[Figure 3]](ba5132fig3mag.jpg)
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Figure 3
Molecular-replacement solutions for the two FAS crystal forms were obtained using a low-resolution EM reconstruction as search model. (a) Translation functions for the P212121 crystal calculated with two different resolution cutoffs. The section z = 0.25 of the asymmetric unit for the translation function (the Cheshire cell; Hirshfeld, 1968  ) is shown. (b) Translation functions for the P21 crystal shown on the same scale. (c) Packing of the FAS molecules in the two crystal forms. (d) Pseudo-symmetry in the primitive orthorhombic FAS crystal form. The primitive orthorhombic unit cell and the twofold screw axes that define space group P212121 are shown in black. A C-centered orthorhombic unit cell with its additional symmetry in the C2221 space group is depicted in blue. The packing of the FAS molecules displays pseudo-C-centered orthorhombic symmetry. The space group is P212121 and not C2221 because the FAS molecule, with its center of mass indicated by a black dot, is offset by 5 Å along the a axis. The 5 Å offset along the a axis is also clearly visible as double peaks in the translation function shown in (a). A monoclinic unit cell is also shown with respect to the orthorhombic geometry and symmetry. |
![[Figure 3]](ba5132fig3.jpg)
| BIOLOGICAL CRYSTALLOGRAPHY |
ISSN: 1399-0047
