 | Acta Crystallographica Section D Acta Crystallographica Section D BIOLOGICAL CRYSTALLOGRAPHY |
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![[Figure 1]](gr2165fig1mag.jpg)
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Figure 1
Map-likelihood phasing of initiation factor 5a. (a) Experimental (MAD) map. (b) Map-likelihood phased map, using experimental phases as a starting phase set. (c) Map-likelihood phased map, using maximum-likelihood density-modified phases as starting phase set. Experimental (MAD) phases for initiation factor 5a (Peat et al., 1998  ) had an overall figure of merit of 0.61 to 2.2 Å. The refined model of initiation factor 5a (PDB entry 1bkb
; Berman et al., 2000) is overlaid on the experimental map. The map is contoured at 1.5σ. In (b), one cycle of map-likelihood phasing was carried out and phase probabilities were calculated from the map likelihood only. The figure of merit of map-likelihood phases was 0.37. The calculation of the solvent mask and the map-likelihood phasing was carried out as described for maximum-likelihood density modification (Terwilliger, 2000), except that experimental phases were not used in the phase-probability calculation. Experimental phases were used in determining the mask, as in maximum-likelihood density modification. In (c), a full set of five mask cycles of maximum-likelihood density modification, each with ten minor cycles of phase improvement, were carried out. These phases were then used to calculate a mask and to initiate one cycle of map-likelihood phasing as in (b). The figure of merit of map-likelihood phasing was 0.50. |
![[Figure 1]](gr2165fig1.jpg)
| BIOLOGICAL CRYSTALLOGRAPHY |
ISSN: 1399-0047
