Yi Xue wrote:
*** For details on how to be removed from this list visit the *** *** CCP4 home page http://www.ccp4.ac.uk ***Hi, all: I tried to solve a protein structure by molecular replacement. The apo form is already solved, I crystallized it with Cu(II). The data diffracted to 1.6A, the highest resolution shell has more than 80% completeness, R is 43%.
what is the space group and cell ? it could be twinning.
I used phaser to find the MR solutin ,then used Refmac to do rigid body refinement, and restrained refinement. I adjusted weighing factor to keep chi^2 exactly 0.01. After these steps, R is around 0.30, Rfree is about 0.37.
I don't understand what you mean with "adjusted weighing factor to keep chi^2 exactly 0.01"I'd suggest to adjust the weighting such that the geometry is reasonable (namely rms bond = 0.015 A, rms angles = 1.5° or in that range)
Then I fed all the data to arp/warp, it showed that while R decresed, Rfree increased, and finally, Rfree is around 40%. I tried to manual build the model, however, I found that most density were unambigously assigned. I only need to do some small adjustments, these minor adjustments did not improve R factors a lot. All suggestions are highly appreciated. Best regards Yi
-- Kay Diederichs http://strucbio.biologie.uni-konstanz.de email: [EMAIL PROTECTED] Tel +49 7531 88 4049 Fax 3183 Fachbereich Biologie, Universität Konstanz, Box M647, D-78457 Konstanz
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