Michael, You did not specify what spacegroup you are using or the % of rejects you are getting. Are you sure that you are in the correct spacegroup? I have seen cases where people have processed their data in the wrong spacegroup, adjusting their error model to give good CHI**2 and Rmerge, with the result that more than 30% of the reflections are rejected.
1) Try processing in a several, lower symmetry, spacegroups. Use the default error model, and do not read the rejections file. Remember the symmetry of the lattice is only an indication of which spacegroups are possible. 2) Process your data in P1 (or a suitably low symmetry SG) and look at the self-rotation plots using MOLREP, GLRP, or CNS. Then you can see what symmetries are actually present in your data before imposing them in scalepack. Ultimately it is the crystal symmetry, not the lattice symmetry, which should determine the correct spacegroup. A crystal lattice may have perfect cubic geometry (a=b=c, alpha=beta=gamma=90) and still be P1 symmetry. It just has a very low probability. So don't you feel lucky to have found such an improbable crystal. Good Luck, Mark On Thu, 2006-11-30 at 12:13 -0500, Michael K Swan wrote: > Hi All, > I have a question about processing in HKL2000. > I have a dataset which looks like it will go out to 2.5A but the problem > is that when I have integrated the 360 frames (180degrees) to 2.4A I get > a large number of rejects on scaling which exceeds the 50000 limit. So > is there any way to increase this limit or another method of reducing > the number of rejects? > I can get scaling to work if I either cut the resolution down to 3.0 or > lower but alternatively if I exclude alot of frames and leave say 90 > then the rejects are below 50000 and the scaling produces data that > looks good to at least 2.6-2.5A according to the I/sigma and an Rmerge > <0.5 in the final shell, however the completeness suffers due to the low > number of frames. > I should also say that I am suspicious that one of the reasons for all > the rejects might be that in the centre of the pattern the spots are of > a good radial shape but towards the edge they become more elongated. I > tried using the elliptical spot feature of HKL2000 but this doesn't seem > to be ideal as the spots are not always elongated in the same direction. > Any thoughts or suggestions would be much appreciated, > > Mike Swan. Sincerely yours, Mark A. White, Ph.D. Assistant Professor, Dept. Biochemistry and Molecular Biology, Manager, Sealy Center for Structural Biology and Molecular Biophysics X-ray Crystallography Laboratory, Basic Science Building, Room 6.660 C University of Texas Medical Branch Galveston, TX 77555-0647 Tel. (409) 747-4747 Fax. (409) 747-4745 mailto://[EMAIL PROTECTED] http://xray.utmb.edu http://xray.utmb.edu/~white
