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Perhaps it is just a wrongly labelled cif-file. Did you check with other cif-files from the PDB? -- Tim Gruene Institut fuer anorganische Chemie Tammannstr. 4 D-37077 Goettingen GPG Key ID = A46BEE1A On Thu, 28 Sep 2006, Harry M. Greenblatt wrote: > BS"D > > > Dear All, > > I addressed this issue to "management" but got no reply. > > I wanted to make a map from a published structure, so I downloaded > the structure factors and the coordinates, and used the import > facility to go from mmcif to mtz. Then I ran sfall to generate fcalc > and phicalc from the coordinates. Then fft to make a 2fo-fc map. > Looking at the map in PyMOL and then in coot and contouring at > 1.5sigma, it was obvious that something had gone wrong. While > looking in coot, and pondering what could be wrong, I was idly > scrolling the mouse wheel, which changed the contour. When I got > close to zero, the map suddenly started looking better. Checking the > fft output confirmed my suspicions: the map, instead of going from > -0.6 to +1.6, went from -1.6 to +0.6. Contouring at -1.5sigma gave > what one would expect from a 2fo-fc map. So I guess the map that was > calculated was Fc - 2Fo. > I checked the fft output again and confirmed that FP was F1, > whose multiplier, n, was +2.0 and that Fcalc was F2, whose > multiplier, m, was +1.0 and that I had asked for a nF1 - mF2 map. > > Perhaps I did something wrong? Perhaps this is a bug in fft? > > Thanks, > > Harry > ------------------------------------------------------------------------ > - > Harry M. Greenblatt > Staff Scientist > Dept of Structural Biology [EMAIL PROTECTED] > Weizmann Institute of Science Phone: 972-8-934-3625 > Rehovot, 76100 Facsimile: 972-8-934-4159 > Israel > > >
