- phenixbb - phenix-online.org

preparing DL-Malic acid stock solution
by Sebastiano Pasqualato 08 Jun '17

08 Jun '17

Dear all, we’ve recently having trouble preparing a 3 M stock solution of DL-Malic Acid, pH 7 (which we had, so it’s doable!). When we reach pH 3 - 4 the solution turns milky white and does not goes back to a clear solution even when the pH is raised. Does anybody have any advice on how to get a clear solution? Has anyone gone through the same? Thanks in advance, ciao, Sebastiano -- Sebastiano Pasqualato, PhD Crystallography Unit Department of Experimental Oncology European Institute of Oncology IFOM-IEO Campus via Adamello, 16 20139 - Milano Italy tel +39 02 9437 5167 fax +39 02 9437 5990 web http://is.gd/IEOXtalUnit

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Re: [phenixbb] AutoSol invalid MTZ column_types error
by Terwilliger, Thomas Charles 08 Jun '17

08 Jun '17

Hi Mintu, I'm sorry about this problem! I should have fixed it already but missed this message from Phil Evans that he posted in January: "Columns N(+) and N(-), both of type I, are recent additions to the output file from Aimless. They are the number of observations merged into I(+) and I(-) respectively" AutoSol doesn't know about these columns and can accidentally guess that they are data. To get around this column, use a command like this to create a data file that does not contain the N(+) and N(-) columns: phenix.reflection_file_converter aimless.mtz --mtz=aimless_noN.mtz --label="I(+" ?where the --label=xxxx command specifies the first few characters of the columns you want to use as I+/I- data. Then use aimless_nonN.mtz instead of aimless.mtz as input to autosol. I will fix this in autosol. Let me know if that does not do it! All the best, Tom T Dear all, I am getting an error message "Invalid MTZ column_types for the given miller_array." while I try to run AutoSol. The last line in the log is "Adding array ['N(+)', 'N(-)'] to output file with type II". Do you have any suggestion how to fix this error? Thanks a lot in advance. Best, Mintu

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comfortable OS X level
by Patrick Loll 08 Jun '17

08 Jun '17

I’m still running Yosemite on my Macs, both because I’m change-averse and because folks reported problems with some crystallographic software upon upgrading the OS. These reports have now faded into the haze of the past, and so I ask, have the issues been resolved? Is it safe to move to Sierra? Thanks as always, Pat --------------------------------------------------------------------------------------- Patrick J. Loll, Ph. D. Professor of Biochemistry & Molecular Biology Drexel University College of Medicine Room 10-102 New College Building 245 N. 15th St., Mailstop 497 Philadelphia, PA 19102-1192 USA (215) 762-7706 pat.loll(a)drexelmed.edu

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ligand - protein close contact
by Nikos Pinotsis 07 Jun '17

07 Jun '17

Dear all, I have a protein-ligand structure with several chains in the AU. After refinement one of the ligands forms a close contact 1.8A with the protein. For the rest of the protein-ligand chains the same interaction is as expected to 2.7-2.8 A forming an H-bond. I tried to adjust this ligand with coot but everytime I am getting back the same 1.8 A close contact. There is enough density for the ligand and I can even see that it can fit better to distance 2.4-2.5A H-bond with the protein Is there a way to constrain this distance to more than 2A? Should I fix the ligand atom that interacts? Unless I am missing something more fundamental. The ligand cif file is the default in phenix, the data set is a quite decent 2.3A. thanks in advance for any suggestions Nikos -- Dr. Nikos Pinotsis Institute of Structural and Molecular Biology Department of Biological Sciences, 3rd Floor, R313 Birkbeck College Malet Street London WC1E 7HX T: +44 (0)207 631 6827 F: +44 (0)207 631 6803 M: +44 (0)792 384 3593

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Composite omit map
by Sam Tang 06 Jun '17

06 Jun '17

Dear all Sorry for a very basic question about generating an omit map. I am trying to generate a SA-omit map for only my ligand but not the protein core of my complex. I presume I can use phenix.composite_omit_map GUI and specify my ligand chain in Atom Selection? All other parameters being the same, I notice that when I did not select any atom the whole structure was divided to 30-40 regions but when I selected my ligand chain it now divides into 89 regions. Is there a reason why and is there any advantage to manually adjust the number of omit regions? Many thanks and regards Sam Biochemistry Programme, School of Life Sciences, CUHK

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Fitting ligand with DM map?
by Sam Tang 04 Jun '17

04 Jun '17

Dear community I guess it may not be a standard practice but I wonder if anyone has tried to use a density modified map for ligand building. My situation is that I am trying to fit a single strand DNA ligand into an enzyme model. The dataset is at 3 Ang, P1 space, with overall completeness of only about 88%. MR was done by the apo-enzyme and the density for the first two-third of the ligand is very good and could easily be modelled. Towards the last one-third the density becomes much weaker so nucleotides cannot be easily put. This is the only dataset so far, so multi-crystal averaging / map averaging is not possible at this stage. NCS averaging is also not possible. We did try to sharpen map during refinement. I understand that DM is usually used to improve phase at the initial stage esp. with experimental phasing. With MR would you think density modification could produce a better map to aid the modelling of the last one-third ligand? Can I use the denmod.mtz directly for manual model building? Any input would be very much appreciated. Best Sam Biochemistry Programme, CUHK

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Questions on TLS output and more info on phenix.tls
by Michael Garavito 30 May '17

30 May '17

I am finishing the final stages of refinement with TLS at 1.7 Å and want to begin some B-factor analysis. Also, I am setting up for a series of ensemble refinements. However, I am second guessing myself and have been finding that several basic questions that are not explicitly answered by the Phenix documentation. (1) Just to be sure, I looked for the definition of what is written in the ATOM records of the output PDB file after refinement with TLS: residual B or total B (residual B + TLS contribution). I always thought the latter after refinement with TLS, but nothing was explicitly stated. (2) Also, I have looked for it extensively in the Phenix documentation, I have not found any information on phenix.tls, even though in several places (e.g., phenix.ensemble_refinement), there are explicit references to phenix.tls: “If TLS is used the TLS components must be present in the atom records (see phenix.tls)” The information from just doing % phenix.tls -h does not give enough insight into options and there use. Can someone point me to the right place to get these answers? Thanks, Michael **************************************************************** R. Michael Garavito, Ph.D. Professor of Biochemistry & Molecular Biology 513 Biochemistry Bldg. Michigan State University East Lansing, MI 48824-1319 Office: (517) 355-9724 Lab: (517) 353-9125 FAX: (517) 353-9334 Email: garavito(a)msu.edu ****************************************************************

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Linking C-Type Heme
by Julian Esselborn 24 May '17

24 May '17

Hi list, that might sound like a stupid question, but we are having some trouble getting phenix.refine acknowledging a c-type linkage of a heme. That is a covalent Cys SG bond to C18 or C25 in the heme. The pdb file does contain a LINK record for this, but Ready Set seems to ignore that even if told to look for LINK records. The distance in the model is actually around 1.9 Ä and automatic ligand linking is on and set well below that distance. Any ideas why this might be failing and what is the smartest way to proceed? Any ideas highly appreciated. Thanks a lot Julian Esselborn Tezcan Lab UC San Diego

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Research Track Assistant Professor Positions
by Diana Tomchick 22 May '17

22 May '17

Assistant Professor, Research Track Department of Biophysics The Structural Biology Laboratory at UT Southwestern Medical Center currently has two openings at the non-tenure track Research Assistant Professor level for highly-motivated individuals who enjoy working in a collaborative, multi-disciplinary setting. · Position #1: Cryo-electron microscopist with extensive experience in high resolution single-particle reconstruction, including sample grid preparation, data collection, the use of modern software for particle picking and classification, map generation, model building and structure validation. Experience in cryo-EM tomography is a plus. · Position #2: X-ray crystallographer with extensive experience in modern methods of crystallization, data collection using home and synchrotron sources, structure solution via various experimental techniques, refinement and structure validation. For both positions, a Ph.D. in biochemistry, chemistry, physics or a related field is required. Facility with related techniques for each position such as cryo-electron microscopy, X-ray crystallography, NMR, small-angle X-ray scattering, isothermal titration calorimetry, analytical ultracentrifugation and protein expression and purification is highly desirable. Job requirements include a significant amount of both formal and informal teaching, and teaching experience is highly desirable. Salary is competitive and commensurate with experience and qualifications. About the UT Southwestern Structural Biology Laboratory The Structural Biology Laboratory (Diana Tomchick, Director) is a platform that allows researchers with different expertise to come together in a collaborative setting and tackle biological problems in a comprehensive way. Our publications are representative of the success of this strategy: http://www3.utsouthwestern.edu/sbl/Publications.html State-of-the-art equipment is currently installed, operational and shared between the members in the Structural Biology community at UT Southwestern. Cryo-EM equipment consists of one 300 kV Titan Krios microscope, one 200 kV Talos Arctica microscope, and a cryo-Scios DualBeam for cryo-FIB milling. In addition, the Structural Biology Laboratory has a dedicated lab for cryo-EM grid preparation, with an FEI Vitrobot and assorted instruments for sample prep. Computational facilities include a campus high-performance computing cluster. Crystallographic equipment includes an Art Robbins Gryphon crystallization robot and a Scorpion liquid handling robot, a Jansi UVEX UV microscope, a Rigaku FRE superbright rotating anode X-ray generator with an ACTOR sample mounting robot, and 30 days of guaranteed synchrotron beam time at Sector 19 of the Advanced Photon Source. These facilities are supplemented by a variety of biophysical instruments supporting the study of macromolecules using NMR, CD, dynamic light scattering, analytical ultracentrifugation, stopped-flow kinetics, isothermal titration calorimetry, microscale thermophoresis and mass spectrometry. Applicants should submit a curriculum vita and three letters of reference by July 10, 2017 to Diana Tomchick, Chair, Structural Biology Laboratory Search Committee, U.T. Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-8816. UT Southwestern is an Affirmative Action/Equal Opportunity Employer. Women, minorities, veterans and individuals with disabilities are encouraged to apply. For further inquiries, please contact: Diana Tomchick Department of Biophysics, Rm. ND10.214A UT Southwestern Medical Center 5323 Harry Hines Blvd Dallas TX 75390-8816 Tel. +1 214 645 6383 Email: Diana.Tomchick(a)UTSouthwestern.edu<mailto:[email protected]> ? ************************************************** Diana R. Tomchick Professor Departments of Biophysics and Biochemistry University of Texas Southwestern Medical Center 5323 Harry Hines Blvd. Rm. ND10.214A Dallas, TX 75390-8816 Diana.Tomchick(a)UTSouthwestern.edu (214) 645-6383 (phone) (214) 645-6353 (fax) ________________________________ UT Southwestern Medical Center The future of medicine, today.

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Amit D invited you to check out Dropbox
by Dropbox 21 May '17

21 May '17

Hi there, Amit D (amitd453(a)gmail.com) thinks you should use Dropbox! It’s a free and easy way to access and share your docs, photos, and videos with colleagues and friends—even if they don’t have Dropbox accounts. Accept invite[1] Get started through this email, and you’ll get an extra 500 MB added to your 2 GB of free space. Happy Dropboxing! [1]: https://www.dropbox.com/l/AADiCZMqlucm1Gb-DwLfoxb-Ub8mVCIREm0

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