[ccp4bb] AW: [ccp4bb] Rfree below Rwork

2015-06-30 Thread Herman . Schreuder
You should go back to the output you got during data processing to see which space groups had been proposed by the data processing software and reprocess in the correct space group. Alternative, you could use Zanuda (validate space group button in ccp4i) to find the correct space group. It will

Re: [ccp4bb] Rfree below Rwork

2015-06-30 Thread Smith Liu
If both the PDB and mtz for the pdb have been assigned to P1 space group for some reason, can this lead to Rwork higher than Rfree during refinement? If after converting my PDB and mtz to P1 space group, and I have forgotten what is the original space group for my PDB and mtz before conversion

[ccp4bb] Postdoctoral position

2015-06-30 Thread Zheng, Lei
A postdoctoral position is available immediately in the University of Texas Houston Medical School, Department of Biochemistry and Molecular Biology, Center for Membrane Biology. The successful applicant will focus on structural determination of membrane transporter protein using X-ray crystallo

Re: [ccp4bb] Rfree below Rwork

2015-06-30 Thread Keller, Jacob
Regarding what Eleanor said: The program “labelit,” available within Phenix from command line, can check automatically for higher space groups. In the labelit documentation/homepage it mentions the command: labelit.check_pdb_symmetry [pdb coordinate file] [data=mtz file] JPK From: CCP4 bu

Re: [ccp4bb] Rfree below Rwork

2015-06-30 Thread Robbie Joosten
Hi Wolfram, You didn’t tell us where your model came from but 10 cycles of TLS and 10 cycles of restrained refinement is not enough for a refinement to converge if you just picked your test set. Try resetting your B-factor and doing 30-40 cycles refinement in REFMAC. Cheers, Robbie

Re: [ccp4bb] Rfree below Rwork

2015-06-30 Thread Eleanor Dodson
I suppose if I was the referee for this structure and your FreeR is so close to the Rfactor I would ask you to ensure you had the right space group - is the 6 fold NCS actually 2 fold NCS with a crystallographic 3 fold.. Cases occur where R32 is indexed as C2.. Certainly if the Rfree set is assign

Re: [ccp4bb] Rfree below Rwork

2015-06-30 Thread Gerard Bricogne
Dear Wolfram, I have a perhaps optimistic view of the effect of high-order NCS on Rfree, in the sense that I don't view it as a "problem". People have agonised to extreme degrees over the "difficulty" of choosing a free set of reflections that would produce the expected gap between Rwork and

[ccp4bb] Rfree below Rwork

2015-06-30 Thread wtempel
Hello, my question concerns refinement of a structure with 6-fold NCS (local automatic restraints in REFMAC) against 2.8 A data. The size of my free set is 1172 selected in thin resolution shells (SFTOOLS) and corresponding to 4.3 % of reflections. A refmac run of 10 cycles of TLS and 10 cycles of

Re: [ccp4bb] Phaser solution and solvent content for arp warp

2015-06-30 Thread Edward A. Berry
A little bit confused about the 30 molecules. Superimposed models from the nmr structure in one or two copies ofone ensemble? Anyway, Arp-warp just uses the model to calculate phases for an initial map. How about forgo the model and give it a map with phases from the successful phaser run? It l

Re: [ccp4bb] Interesting DNA contamination

2015-06-30 Thread FOOS Nicolas
Hi Chiara, according to my own experience, interaction between protein and DNA can be strong enough to "protect" DNA from DNAse action. To explain why with protease only the band disappeared, i need to know if the gel was run for long time, and if it's concentrate or not. Because if the DNA fr

Re: [ccp4bb] Interesting DNA contamination

2015-06-30 Thread Chiara Rapisarda
> Hi, I found that my protein bound ethidium bromide in an agarose gel. I tested that by treating my protein with protease and DNAse in two different tubes and running a gel. The band in the agarose gel disappeared only when the protein was treated with protease. It is worth trying. I hope that