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Get R values without refining in phenix.refine
by Murpholino Peligro 17 Jun '15

17 Jun '15

How can I get R values without refining anything? Just to check if my newest model is better than the old one?

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Re: [phenixbb] anomalous difference map calculation
by Alexandra Marques 17 Jun '15

17 Jun '15

Thank you very much for your replies. Here is what I did: 1)I rerun xdsconv again with Friedls law=false in order to get the mtz file with the F(+) and F(-) columns (new.mtz). 2) I used my pdb file from the last refinement together with the new.mtz file as input for “Calculate maps” in Phenix and selected the option for anomalous map. Now I obtained the ANOM PHANOM map. I hope this is correct… In the anomalous map the largest density is in the Mo and Fe atoms. There is no density in the S of SO3 or SO4 groups, so, this will not help me to decide whether there are SO3 groups in the structure (because for the SO4 I have no doubt). However, while searching the mailling list I foud this post http://www.phenix-online.org/pipermail/phenixbb/2009-September/013799.html which worried me. Should I have used from the beginning this “new” mtz file with F+/F- in order to obtain anomalous differences map at each refinement step? Do you think that I should go back, transfer the R-free flags to my new mtz file and repeat all the refinements? Best regards, Alexandra 2015-06-17 16:59 GMT+01:00 Pavel Afonine <pafonine(a)lbl.gov>: > Hi Alexandra, > > to get anomalous difference map you do not need to do anything special: > phenix.refine calculates this map by default as long as your input data are > Fobs(+) and Fobs(-) or Iobs(+) and Iobs(-). > > Refining occupancy of Mo may not be a bad idea given it is likely to be > partially occupied. > > Pavel > > > On 6/17/15 06:04, Alexandra Marques wrote: > > Hi, > > > I am in the last refinement steps of a MR model and I want to calculate > an anomalous difference map essentially to confirm the presence of a > sulfite molecule and to locate vanadium (present in soaking solution). I > read that it is necessary to have a mtz file with anomalous data (i.e. > F+,F- or I+,I-). However, my data was collected at “normal” wavelenght > (0.97) and it was processed with XDS considering Friedls law= true and my > mtz file contain the following columns: H K L FP SIGFP. So, can I still > calculate a anomalous difference map based on my data? > > > Since I also have a Mo atom in the active site can I try to refine its > occupancy by using the option “anomalous groups” in the refinement > strategy? > > > Thank you very much, > Alexandra > > > _______________________________________________ > phenixbb mailing [email protected]://phenix-online.org/mailman/listinfo/phenixbb > Unsubscribe: phenixbb-leave(a)phenix-online.org > > >

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anomalous difference map calculation
by Alexandra Marques 17 Jun '15

17 Jun '15

Hi, I am in the last refinement steps of a MR model and I want to calculate an anomalous difference map essentially to confirm the presence of a sulfite molecule and to locate vanadium (present in soaking solution). I read that it is necessary to have a mtz file with anomalous data (i.e. F+,F- or I+,I-). However, my data was collected at “normal” wavelenght (0.97) and it was processed with XDS considering Friedls law= true and my mtz file contain the following columns: H K L FP SIGFP. So, can I still calculate a anomalous difference map based on my data? Since I also have a Mo atom in the active site can I try to refine its occupancy by using the option “anomalous groups” in the refinement strategy? Thank you very much, Alexandra

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keep torsion restraint on ligand
by CPMAS Chen 17 Jun '15

17 Jun '15

Hi, All Phenix Users, I am fitting 2-bromoethanol to the density map. I want to keep its gauche conformation, so I edited the cif for this ligand to restrain the torsion angle, loop_ _chem_comp_tor.comp_id _chem_comp_tor.id _chem_comp_tor.atom_id_1 _chem_comp_tor.atom_id_2 _chem_comp_tor.atom_id_3 _chem_comp_tor.atom_id_4 _chem_comp_tor.value_angle _chem_comp_tor.value_angle_esd _chem_comp_tor.period BRJ Var_01 BR1 CB CB1 OB1 -60.00 0.0 3 But, after refinement, this angle can be close to 90 or even 120. Even worse is that the fitting at such angles are not better than at -60/60 angle. How could I fix/restrain the angle during refinement? Thanks! Charles *************************************************** Charles Chen Research Associate University of Pittsburgh School of Medicine Department of Anesthesiology ******************************************************

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Re: [phenixbb] anomalous difference map calculation
by Ashok Nayak 17 Jun '15

17 Jun '15

Hello Alexandra, I believe you have to reprocess the data keeping friedel pairs (f+ and f- ) separate to make use of the little most anomalous signal (if any) at your collected wavelength. The best thing would be to collect a high redundant set of peak data (if not all the three data sets including mad remote and inflection data) If you have access to a tunable source and xtals left. Once you process differently, you can do all sorts of substructure search and later refine anomalous scatterers using wavelength, atom type and f ' and f“ values. Sulphur sad is also a good possibility if you have a decent nmbr of sulphurs in your protein. Hope this suffices your query. Regards Ashok Nayak CSIR CDRI, Lucknow, India Alexandra Marques <at.marques(a)fct.unl.pt> wrote: >_______________________________________________ >phenixbb mailing list >phenixbb(a)phenix-online.org >http://phenix-online.org/mailman/listinfo/phenixbb >Unsubscribe: phenixbb-leave(a)phenix-online.org

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phenix refine of my EM data
by Smith Liu 17 Jun '15

17 Jun '15

Dear All, By phenix.real_space_refine, I have fitted the a PDB file to an EM map, with Ramachandran favored around 90% and acceptable level of Ramachandran outlier (1.5%) and rotamer outlier (1.2%). Besides visual checking indicating the fitting of the main chain and sid chains to the dnsity map is acceptable. I hope the refine results can be improved by phenix reciprocal space refine. By phenix.map_to_structure_factors I convert my mrc file to mtz file, with the above mentioned phenix.real_space_refine refined pdb amd mtz files as the input files for the graphical phenix refine, in which I never select real space refine, and I always check xyz coordinates and Group B-factors (sometimes I check xyz coordinates and individual B-factors ). Fot this kind of phenix reciprocal space refine, I find the molprobity anslysis results have improved a little, but I find both the contouring level of 2FOFCWT map and the FOFCWT map is more than thousands of thousands high (and it seems the contouring level of FOFCWT is much higher), and visual checking indicated both the main chain and side chains hardly fit with the density map. But I really find there were publications which did phenix.real_space_refine first, and then process the reciprocal space refine, which get good results as introduced in the publications. Will you please tell me why my phenix reciprocal refine after phenix.real_space_refine did not work? Best regards. Smith

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on phenix.map_to_structure_factors
by Smith Liu 13 Jun '15

13 Jun '15

Dear All For phenix.map_to_structure_factors, it needs to input the resolution d_min. But for an EM map, usually the resolution is the general resolution of the whole map (or to some extent the average resolution of the whole map). Is d_min for phenix.map_to_structure_factors the general EM map resolution, or the best resolution of the whole EM map, which is only for part of the EM map with the best quality? Smith

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on real_space_refine
by Smith Liu 12 Jun '15

12 Jun '15

Dear All, After fitting a PDB into a 3.5-5 A resolution EM map by phenix.real_space_refine, should I still need to do a reciprocal space refine? For crystallography, the reciprocal space is in fact not purely imaginary, it corresponds to the diffaction spot. But for the EM data refinement, what is the reciprocal space refine? And what reciporce spce refine works on for the data refinement? Smith

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refinement of ligands and waters
by Alexandra Marques 10 Jun '15

10 Jun '15

Hi, I still have little experience in the refinement of protein structures. So, I have some (basic) doubts that I would like you to help me please. 1) I have a metal coordinated to a cofactor in the active center of my protein structure. The initial solution provided by phaser/autobuilding already contained the metal+cofactor modelled in the density but with zero occupancy. Then I created all the necessary restraints and cif files with phenix_ready_set and did two cycles of model building/phenix refinement. The refined structures always contained zero occupancy for those atoms. My question is: should I manually change the occupancy for the metal+cofactor to 1? I thought this would be made automatically by phenix because I selected the option “occupancies” and “individual B-factors” in the refinement strategy… 2) When manually placing waters in the density with coot, what is the maximum value of B-factor that is acceptable for a water? I am asking that because I have some water molecules with weak density and consequently B-factors between 45 and 55 but that are involved in interactions with other molecules. Is it better to keep those waters or remove them? Best regards, Alexandra

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does the lastest Phenix only support windows 7
by Xiao Lei 09 Jun '15

09 Jun '15

Hi All, I am a beginner of crystallography and I'd like to install Phenix. I tried to download phenix for my Windows 8.1 system (64bit) but in the download page it says "64-bit (Windows 7 only) ". I do not know if I really have to use Windows 7. Does anyone have experience of installation Phenix on Windows 8.1? Thanks ahead. Xiao

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