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phenix.autobuild sa_omit map
by Jianghai Zhu 03 Apr '09

03 Apr '09

Hi, I am using phenix.autobuild to calculate a sa_omit map. The find_ncs is Auto by default. What does Auto mean here? Should I turn it off or does it matter? Thanks. -- Jianghai

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refinment of ligand
by peter hudson 02 Apr '09

02 Apr '09

Hello all I have refined and built model a dataset of 3.0A resolution dataset. This model is assocaied with a ligand. After final refinement and model building i found a big blob of Fo-Fc density of around 4sigma level at the N-terminal of the fianl model. My protein doesnot carry any tag at the N-terminal. But, the template i have used for the molecular replacement carrying a tag at the N-termianl, which can occupy only 1/4th of this positive density after superpostion. My crystallisation conditions component cannot occupy such higher level of positive density. Since my protein binds to a ligand, i looked carefully to the positive density and it seems very similar to the ligand density but its obscure. Refinement after fitting the ligand leads to very high B-factor of the ligan, which vary for various atoms from 50-90 and simultaneously positive density goes off. I also tried to change the occupancy of the ligand but as i reduce the occupancy the B factor comes down at the noraml expected average B factor value but again Fo-Fc density appears in the map over ligand. If i leave to refine the occupancy to the programme automatically, this lead to the zero occupancy of the few atoms in the ligand and avearge B factor remains normal. suggestions would be appreciated. Thanks in advance Peter

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phenix.autobuild disappeared
by Andreas Förster 02 Apr '09

02 Apr '09

Hey there, sorry for the brainfreeze but I can't find phenix.autobuild. It's not part of cci_apps Versions 2008_09_13_0905 or 2009_02_15_2320. What happened? How do I build? Andreas -- Andreas Förster, Research Associate Paul Freemont & Xiaodong Zhang Labs Department of Biochemistry, Imperial College London http://www.msf.bio.ic.ac.uk

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Re: [phenixbb] phenixbb Digest, Vol 40, Issue 31
by Marjolein Thunnissen 01 Apr '09

01 Apr '09

> > Hi Marjolein, > >> I have been trying to find in the documentation if there is a way to do this >> but I have the following problem: In a recent structure we are currently >> refining we identified a spermine molecule sitting right on a >> crystallographic two-fold axis. Spermine has internal two-fold symmetry and >> it is part of extensive crystal contacts. I just wonder how to refine this >> with Phenix. In Refmac it is easy, I put the occupancies to 0.5 and the >> program ignores the clashes of the symmetry related molecule, but that >> doesn't seem to be the way that Phenix works. Can anyone give me advise on >> this? > > Supporting the occupancy trick is on my to-do list (fairly high up). > > In the meantime, could you try giving only the asymmetric unit of the > spermine? I.e. delete all duplicate atoms from your pdb file. > The restraints across the symmetry bond will not work automatically. > You have to define a "custom bond" instead, and if you also want to > restrain the angles, custom pseudo-bonds. See the > "Definition of custom bonds and angles" section. > In your case you'll have to define symmetry_operations (not shown > in the docs), e.g.: > > bond { > action = *add > atom_selection_1 = resname SPM and name C7 > atom_selection_2 = resname SPM and name C7 > symmetry_operation = -x,-y,z > distance_ideal = 1.5 > sigma = 0.01 > } > > The main difficulty will be to find the correct symmetry_operation > for each custom bond. If you send my the CRYST1 card from your > PDB file and the part with the SPM residue I could help out. > > Ralf > > > ------------------------------ Hi, The commands worked indeed the trick. Luckily it is actually not that difficult to find the symmetry operators when using coot. One just has to switch drawing symmetry atoms on and clicking on a symmetry atom, coot will tell you in the bottom line which atom it is and which symmetry operator was used to draw it... Thanks again Marjolein __________________________________________________________________________ | Marjolein Thunnissen Phone +46-(0)46-22 24584| | Associate Professor Fax +46-(0)46-22 24692| | Dept of Molecular Biophysics, Lund University http://www.mbfys.lu.se | | PO-Box 124 S-221 00 Lund, Sweden | | | |Scientific coordinator I911 (Max-lab): MAD and fixed-wavelength stations | | for macromolecular crystallography | |__________________________________________________________________________|

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Re: [phenixbb] PHENIX user mailing list <[email protected]>
by Ralf W. Grosse-Kunstleve 31 Mar '09

31 Mar '09

Hi Maia, > I have a Ca2+ ion in a special position. the ocupancy should be 0.5, as > the other half belongs to a symmetry-related molecule. However, > refinement makes the occupansy 1. What should I do to prevent this? > Should not it find automatically that? phenix.refine uses the correct symmetry factor automatically (internally). Unless you have an actual partial occupancy, the occupancy factor in the pdb file should be 1, irrespective of the multiplicity of the special position. Let me know if this doesn't answer your question. Ralf

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can I turn off TLS for subsequent rounds of refinement?
by Scott Classen 31 Mar '09

31 Mar '09

Hi all, As the TLS refinement can take a significant amount of time, I'm wondering if I can turn it off after a few rounds with it on? or will phenix.refine "see" the ANISOU records and assume I am doing anisotropic ADP? Thanks, Scott

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phenix automr
by sbiswas2＠ncsu.edu 31 Mar '09

31 Mar '09

Hi all, I tried to use phenix automr by using the gui and also I am using the latest version of phenix (courtesy of the phenix development team). I asked it to search for two molecules in the asymmetric unit but it finds just one also I am getting negative (-29) LLG value for the final solution. The map also does not look good. I also asked it to search for all possible space group, although I processed the data with P43212 phenix automr finds a different one P41212.Will fixing the space group fix the problem? Does anyone know what is going on? I tried running phaser separately through ccp4 and phaser did find two molecules although the map did not look good in this either. Shya

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Missing map for model
by Folmer Fredslund 30 Mar '09

30 Mar '09

Dear all, In phenix.refine (1.4-3) my electron density maps look weird. I get beautiful density for a helix that is missing from the current model, but absolutely horrible density for the rest of the molecule. Any ideas what is going on? Maps from automr look fine and the density modified map from autobuild also look fine, whereas the autobuild map from refinement has the same features. Any ideas what is going on? I am running all programs with default parameters. Best regards, Folmer Fredslund

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Geometry problem with the ligand
by Jhon Thomas 30 Mar '09

30 Mar '09

Hello all I am working with a 3.0 A dataset, which binds with cAMP. I have refined the dataset with phenix (TLS+Group_adp) and followed by weight optimization. Though cAMP fit well in the density, validation tools (molprobity, procheck) suggest the bond angles and bond lengths of ligand of completely refined model is very bad(100% bad). Can anyone suggest what could be the problem with model or refinement? I will appreciate the suggestions. Thanks in advance John

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weight optimization
by peter hudson 30 Mar '09

30 Mar '09

Hello all I am very new to this field. I am refining a dataset of 3.0A resolution. I want to perform the weight optimization. while weight optimisation, occupancy refinemnet is default. I donot want torefine the occupancy of any of the atoms from my model. How can i set to occupancy_refinemnet=false. I will appreciate the suggestions. Thanks in advance Peter

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