SIR data consisting of the native and Hg-derivative (d14) of the protein (R)-phycoerythrin at 2.8Å resolution was used in the test. SOLVE/RESOLVE run in the default mode led to a model containing 454 of the total of 668 residues, 29 among them have been docked in the sequence. A portion of the resultant electron density map is shown on the left of the above figure. Based on this model, 7 cycles iteration of OASIS+DM+RESOLVE (build only) brought to a model of 547 residues, 133 of which docked into the sequence. The same portion of the improved electron density map is shown on the middle of the figure. Two more cycles of OASIS+DM+RESOLVE iteration were carried out, the input used for which was the merged result of the last output in the previous test and the original output of SOLVE/RESOLVE. This led to a model containing 452 residues, of which 173 residues have been docked into the sequence. The same part of the electron density map is shown on the right of the figure. It is concluded that the iteration of OASIS+DM+RESOLVE (build only) is a useful tool in phasing and fragment extension with SIR data.
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By Y. He1, Y.X. Gu1, C.D. Zheng1, Z.J. Lin2, H.F. Fan1 & T. Jiang2

1Institue of Physics, Chinese Academy of Sciences, Beijing 100080, China
2Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China