 | Acta Crystallographica Section D Acta Crystallographica Section D BIOLOGICAL CRYSTALLOGRAPHY |
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![[Figure 8]](ea5067fig8mag.jpg)
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Figure 8
Factors limiting the usefulness of extrapolated maps. OMIT electron-density maps calculated from extrapolated structure factors (FBex) are shown as a function of f. The top row shows the effect of the error introduced by the SASFE procedure itself. The FBex values for the maps in this row were obtained to 1 Å resolution by SASFE using calculated structure factors for FA and FAB based on the atomic models shown in Fig. 4 ![[link]](../../../../../../logos/arrows/d_arr.gif) (a). The bottom row illustrates the effect of the inevitable amplification of experimental uncertainties during SASFE (see equation 15). The maps are `mock extrapolations' (i.e. FA = FAB = FB = FBex except for experimental error) based on two experimental 1.2 Å resolution data sets from a fully dark-adapted PYP crystal. Therefore, changes in these extrapolated maps arise solely from the amplification of experimental error inherent in any extrapolation procedure. The error introduced by SASFE's scalar approximation causes virtually no deterioration in map quality. In comparison, the propagation of the experimental uncertainties leads to a rapid deterioration of the quality of the extrapolated maps and the apparent resolution. |
![[Figure 8]](ea5067fig8.jpg)
| BIOLOGICAL CRYSTALLOGRAPHY |
ISSN: 1399-0047
