- phenixbb - phenix-online.org

Occupancy refinement of anomalous scatters
by Chen Zhao 09 Sep '14

09 Sep '14

Hi all, I have a question about the occupancy refinement of the anomalous scatters. This is because when I went through all the HA sites, I found that some of them has too high B factor and too high occ. I manually adjusted the occ and fed the model into refinement, but the B factor and occ came back to around their original level again. It seems that those have a stronger peak in the anomalous difference Fourier map has a higher occupancy after refinement, but this does not necessarily equals to a strong density peak in 2Fo-Fc map (some of them even disappear after refinement), and this might be related to their high B factor. Am I doing something wrong in the refinement? I am basically using phenix.refine default setting, but with TLS+isotropic B factor refinement and occupancy refinement of a small region (5-8 residues). The resolution is 3 A, and the refinement is already at the final stage. I am still at the learning stage and your input will be greatly appreciated. Thank you! Sincerely, Chen

2 1

Refinement and Density modification
by Ashu S 09 Sep '14

09 Sep '14

Dear all, I am working on a 3.6A Se SAD data. Autosol followed by autobuild gave a decent map (as expected at this resolution) with a moderate trace. After building poly ala trace and assigning few resides in and around Se positions when I refine the model, all the sharp features of the electron density map are lost. For example, a nice looking helical density becomes a tube. I presume that this happens because wilson B is high (~110 A2) and the map requires modification, sharpening etc. Is there a way to get the map with similar sharp features after model building and refinement as auto build gives? How could I follow exactly the same steps of density modification etc which auto build does? Thanks, Ashu

2 1

Refinement and Density Modification
by Ashu S 08 Sep '14

08 Sep '14

Dear all, I am working on a 3.6A Se SAD data. Autosol followed by autobuild gave a decent map (as expected at this resolution) with a moderate trace. After building poly ala trace and assigning few resides in and around Se positions when I refine the model, all the sharp features of the electron density map are lost. For example, a nice looking helical density becomes a tube. I presume that this happens because wilson B is high (~110 A2) and the map requires modification, sharpening etc. Is there a way to get the map with similar sharp features after model building and refinement as auto build gives? How could I follow exactly the same steps of density modification etc which auto build does? Thanks, Ashu

1 0

refine anomalous
by Andreas Förster 08 Sep '14

08 Sep '14

Dear all, I've solved a structure from a SAD dataset collected at 1.54 Å. The structure contains a good number of sulfurs and also what I think is a potassium ion. To verify, I chose a refinement strategy including "Anomalous groups". This worked well in an important way - R values down by 2 percentage points - but the refined f' and f" values are way off. I start out with these parameters in *.eff: anomalous_scatterers { group { selection = (name SD or name SG) f_prime = 0.319342 f_double_prime = 0.557592 refine = *f_prime *f_double_prime } group { selection = name K f_prime = 0.365562 f_double_prime = 1.06736 refine = *f_prime *f_double_prime } } What I get back is: Anomalous scatterer group: Selection: "(name SD or name SG)" Number of selected scatterers: 15 f_prime: -1.15797 f_double_prime: 0.00577091 refine: f_prime f_double_prime Anomalous scatterer group: Selection: "name K" Number of selected scatterers: 1 f_prime: -4.41689 f_double_prime: 0.00271946 refine: f_prime f_double_prime I thought I'd get close to the book values for S and would be able to identify the other anomalous scatterer by the refined f'/f" values. Naiveté or stupidity? Thank you. Andreas -- Andreas Förster Crystallization and X-ray Facility Manager Centre for Structural Biology Imperial College London

2 1

Fwd: Re: Sculptor
by Gabor Bunkoczi 08 Sep '14

08 Sep '14

Apologies, this was meant for the BB. -------- Original Message -------- Subject: Re: [phenixbb] Sculptor Date: 2014-09-08 10:41 From: Gabor Bunkoczi <gb360(a)cam.ac.uk> To: Marie Elizabeth Fraser <frasm(a)ucalgary.ca> Hi Marie, please check the extension of your alignment. If it is .pir, the second line is supposed to be a comment line, and it is therefore ignored. You can either change the extension to .ali, or insert an empty line after the ones starting with ">". If this is not the problem, then this is not supposed to happen. Please send me the logfile in the first instance, although I may need the actual alignment and the PDB file as well (you can delete the target sequence if you wish, an alignment with a single sequence is perfectly valid). BW, Gabor On 2014-09-08 01:22, Marie Elizabeth Fraser wrote: > Hello, > I'm running Sculptor from the Phenix GUI, trying to improve a > molecular replacement model. I've given the pdb file and a sequence > alignment. Sculptor does not appear to accept the first residues > aligned in the sequence alignment. In the alignment, these residues > are residue numbers 42 to 60, so they are on the second line of the > fasta file (the first line after the title) and Sculptor starts at > residue 61 (the subsequent line). Residues 42 to 60 of the target are > to match the first residues of the pdb model, so in the alignment, > there are 41 dashes before the beginning of the sequence for the pdb > file. Am I giving an incorrectly formatted sequence alignment, > misinterpreting what Sculptor does or is Sculptor supposed to do this? > Thank you, Marie > > _______________________________________________ > phenixbb mailing list > phenixbb(a)phenix-online.org > http://phenix-online.org/mailman/listinfo/phenixbb

1 0

Sculptor
by Marie Elizabeth Fraser 08 Sep '14

08 Sep '14

Hello, I'm running Sculptor from the Phenix GUI, trying to improve a molecular replacement model. I've given the pdb file and a sequence alignment. Sculptor does not appear to accept the first residues aligned in the sequence alignment. In the alignment, these residues are residue numbers 42 to 60, so they are on the second line of the fasta file (the first line after the title) and Sculptor starts at residue 61 (the subsequent line). Residues 42 to 60 of the target are to match the first residues of the pdb model, so in the alignment, there are 41 dashes before the beginning of the sequence for the pdb file. Am I giving an incorrectly formatted sequence alignment, misinterpreting what Sculptor does or is Sculptor supposed to do this? Thank you, Marie

1 0

refine structure with mtz file in P212121 or P222?
by Wei Shi 05 Sep '14

05 Sep '14

Hi all, I am working with a protein-ligand complex structure. The data was indexed with XDS and mtz file is generated using Phenix---Reflection tools---Reflection file editor. The space group used was P222. Then, I used the Phenix---Molecular replacement to find a solution (try all possible in same pointgroup), and the MR solution was in space group P212121. And then, I reindexed the data in XDS using space group P212121 and then generate the mtz file in space group P212121. So, I have two mtz file, in space group P212121 and P222. When I refine the MR solution with the different mtz files, the map generated is not same for the ligand. The statisitcs is better with P222 mtz file than P212121 mtz file. I am wondering why the density for the ligand and the statistics is different using mtz file in different space groups and which mtz file should I use to get the final structure model. Thank you so much! Best, Wei

2 3

phenix.refine and R free values
by PC 03 Sep '14

03 Sep '14

3 4

OMIT map
by abhishek jamwal 02 Sep '14

02 Sep '14

Dear phenixbb members, I want to build a SA-OMIT map for a ligand present in xtal structure of a protein. I am using "AutoBuild-create omit map" module of PHENIX ver. 1.8.4-1496 (graphical interface) for this purpose. However, when I run the program after adding requisite input files, it gives an error: " The map file parameter is not supported for omit map calculation" Q: What is this "file parameter" and way to fix this error/parameter ? waiting for answers many thanks in advance Abhishek Jamwal Structural Biology Group ICGEB, New Delhi

2 1

Phasing using CryoEM Map
by Alexander Kintzer 02 Sep '14

02 Sep '14

Hello All, I trying to phase my 4Å data with low resolution cryoEM maps (various 12-18Å). There is some documentation, but not really for dealing with EM data. I am having trouble converting the EM data from mrc to suitable F's for phaser. One would want to try different density contours of the cryoEM map, but I haven't found a good way to accomplish this. I also have been unable to search for Ta6Br12 clusters using Autosol even though the documentation seems to suggest that it is possible using the "TX" or "XX" designation for heavy atom search. Any guidance would be extremely helpful. best, Alex

4 3