 | Acta Crystallographica Section D Acta Crystallographica Section D BIOLOGICAL CRYSTALLOGRAPHY |
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![[Figure 6]](ba5132fig6mag.jpg)
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Figure 6
Processing of diffraction images collected from twinned crystals. (a) Section of a diffraction image of a twinned P21 FAS crystal from T. lanuginosus. (b) For this particular crystal, the twin fraction was lower than 0.5 and therefore one of the two twin lattices was stronger and could be indexed. (c) Coordinates of all predicted spot centroids belonging to twin lattice 1 are obtained after refinement of the unit-cell parameters and crystal orientation. (d) All diffraction spots belonging to the strong twin lattice were erased in the raw image by replacing them with a gray circle with a value corresponding to the image background. (e) Diffraction image after spot erasure. (f) Refinement of the unit-cell parameters and crystal orientation of the weak twin lattice was then possible based on the remaining diffraction spots. (g) After integration of the two twin domains, overlapping and partially overlapping reflections were eliminated using the program UNTANGLE (Buts et al., 2004  ). An overlap threshold was applied where reflections from the two twin domains were rejected if the distance between their spot centroids was closer than eight pixels. In the diffraction image shown, spatially separated reflections from the two twins are colored yellow and red, respectively. Alternating zones of overlapping and spatially separated reflections are visible. |
![[Figure 6]](ba5132fig6.jpg)
| BIOLOGICAL CRYSTALLOGRAPHY |
ISSN: 1399-0047
