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B iso average versus B wilson
by Emily Golden 21 Jul '14

21 Jul '14

Dear All, I have a 1.12 A refined structure with and average B of 11.5 but the wilson B is 6. There are a couple of highly mobile loops and water molecules in the structure that are increasing the average B. What is an acceptable difference between wilson B and average B? Thank you, Emily

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phenix.ligandfit does not recognize a list of SDF file names
by Phan, Jason 21 Jul '14

21 Jul '14

Hi All, I'm trying to fit a list of ligands in SD format with phenix.ligandfit using the ligand=ligand.dat (file containing the ligand file names in the same directory) and the file_or_file_list=file_with_list_of_files flag. It complained that the ligand does not exist. I tested a single ligand, ligand=ligand1.sdf, and it worked fine. I tested a list containing pdb file names and it worked fine. I think phenix.ligandfit does not recognize SD-formatted ligands from a list, although it is fine running as a single ligand. PDB format is fine single or list of names. Any suggestions other than converting SDF to PDB or writing a script to run one SDF at a time? Thanks.

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CCTBX questions
by Morten Grøftehauge 21 Jul '14

21 Jul '14

Hi people, I notice that cctbx.python comes with phenix but as far as I can tell from when I run it, look at imported modules with dir(), and compare to the documentation on Sourceforge the version that comes with phenix is abridged. And possibly not the same version as the sourceforge one but they probably are the same. Will it cause any problems with Phenix if I install cctbx from sourceforge? Is it unnecessary? Second question: Is there any better documentation anywhere? I found James Stroud's wiki but that's mainly for structure factor manipulation. Cheers, Morten -- Morten K Grøftehauge, PhD Pohl Group Durham University

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Long Distant Restraints
by Bradley Hintze 18 Jul '14

18 Jul '14

Hey PHENIX, I am wondering if I can define a distant restraint longer that 3A in a custom restraint file? The conventional way of doing this is to provide : refinement.geometry_restraints.edits { C8_C1=chain C and resid 8 and name C1' D10_C1=chain D and resid 10 and name C1' bond { action = *add atom_selection_1 = $C8_C1 atom_selection_2 = $D10_C1 distance_ideal = 9.1 sigma = 0.02 slack = 0.5 } Obviously this is a distant and not bond restraint. 9.1 exceeds the allowed length of 3 for a bond. Is there a different type of restraint that allows longer distances? Thanks! -- Bradley J. Hintze Duke University PhD Candidate Department of Biochemistry

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Refinement cycles
by George Devaniranjan 17 Jul '14

17 Jul '14

Hi, I was wondering if there is a reason for setting the default number of refinement cycles to 3 in Phenix refine? is there a number of cycles at which point it becomes unacceptable to run so many ? Thank you, George

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B factors too high for low resolution data refinement
by 李翔 15 Jul '14

15 Jul '14

Hi everyone, I am working on my low-resolution data (~6.5 A). When I was doing refinement with PHENIX, the B factors remain pretty high (~400, not sure whether it is normal for the data with such resolution.) And B factors further increased after group B factor refinement (~500). Does it mean the group B factors refinement not working or is there a way I can somehow define a limit for B-factors? (I read one previous topic a few years ago which indicates the B factor can not be controlled. Not sure whether it is available now). Thank you very much for your help! Sincerely, Xiang -- Li Xiang Department of chemistry, Purdue University Email：lixiang1642(a)gmail.com

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So what is unique?
by Kenneth A. Satyshur 15 Jul '14

15 Jul '14

There is some disagreement on terms used to deposit data. We need a definition and an algorithm for each definition. "Unique Reflections" My definition is all the possible reflections out to the highest resolution reported not related by symmetry. Where can I find this? The .mtz contains a list of all HKL calculated to the highest resolution. Usually, we are not able to measure all these diffraction spots due to limits of the detector, mechanical limits, crystal orientation, etc. 'Total reflections' The depositions server asks for total reflections. I assume it wants only those unique reflections we were able to collect, regardless of the sigma cut off. These are called 'observed'. The total we use in refinement will be a subset of the 'unique observed' that are cut on sigma. However, some crystallographers believe that we should not cut on sigma since some of the intensities may in fact be zero. Is this a question for the Refmac and Phenix people? Please give us some guidance and maybe a reference or two that we can use. thanks -- Kenneth A. Satyshur, M.S.,Ph.D. Senior Scientist University of Wisconsin Madison, Wisconsin 53706 608-215-5207

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cifs still in pdb v2
by Guenter Fritz 14 Jul '14

14 Jul '14

Dear Pavel and Nat, can you include in future phenix versions the FAD.cif, NAD.cif and data_NAI.cif / NAI.cif in pdb v3? Currently both are still pdb v2. I usually simply copy the cifs pdb v3 into the mon_lib directory , but sometimes I forget it and stumble over it. Thanks and best wishes, Guenter

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Maximum-likelihood score calculation
by Jouko Virtanen 12 Jul '14

12 Jul '14

Hi all, I would like to calculate the maximum-likelihood score given an input structure and an mtz file. How can I do that? Thanks in advance. Best regards, Jouko

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Real space implementation of DEN refinement?
by Oliver Clarke 11 Jul '14

11 Jul '14

Hi all, Just wondering whether there is any capacity to include DEN restraints in phenix.real_space_refine, e.g. as implemented in the program DireX (see ref below), or any possibility of implementing such in a future release of PHENIX? This would be very handy for refinement of models into low resolution maps (particularly EM maps). Also, on a different but related topic, does anyone have any suggestions as to how to handle model validation (local and global) at low resolution in real-space? It seems as though there is not a solid consensus on how to handle this. Many thanks, Oliver. 1. Schröder, G. F., Brünger, A. T. & Levitt, M. Combining Efficient Conformational Sampling with a Deformable Elastic Network Model Facilitates Structure Refinement at Low Resolution. Structure 15, 1630–1641 (2007).)

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