December 2009 - phenixbb - phenix-online.org

Can PHENIX write the peak list to a PDB file?
by Joe Krahn 04 Dec '10

04 Dec '10

PHENIX has an option to find positive and negative peaks, but only lists them in the log file along with the residue they are closest to. Is it possible to write out the actual peak coordinates, such as to a PDB file? Thanks, Joe Krahn

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Bad ligand parameters
by Joe Krahn 21 Oct '10

21 Oct '10

I found that residue TRS has different dihedral target angles for the three hydroxyl oxygens, which are actually all equivalent. They have a periodicity of 1, but should have a periodicity of 3. What is the best way to handle such discrepancies? Most ligand parameters are probably auto-generated based on a reference structure, and there is probably a lot of conformation bias. In this case, it seems that parameterization should have been able to detect symmetry. It would be nice if parameters could include information about whether a human has done any validation. Actually, a ligand Wiki might be nice, where people can easily put comments, even if they are not sure about how to improve the parameters. Joe Krahn

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Re: [phenixbb] phenix.automr ensemble/component question
by Thomas C. Terwilliger 23 Jul '10

23 Jul '10

Hi Scott, Your first command looks good to me. It is saying that the composition of the crystal is 2 copies of each chain: component_1.component_copies=2 component_2.component_copies=2 and you want to search for 2 copies of each of your search models: ensemble_1.copies_to_find=2 ensemble_2.copies_to_find=2 All the best, Tom T > Hi Phenixers, > > I'm a bit confused about the proper syntax for my phenix.automr job. > This is probably a simple concept, but I'm running on 3 hours of sleep > as my kid was up all night, and my synapses aren't working so good. > > I expect 2 copies of my protein per AU > > My protein is composed of two domains > > I have a single PDB search model for each domain > > is either of these commands correct? > > phenix.automr data=mydata.sca \ > ensemble_1.coords=domain1.pdb \ > ensemble_1.identity=95 \ > ensemble_1.copies_to_find=2 \ > component_1.mass=40579 \ > component_1.component_copies=2 \ > ensemble_2.coords=domain2.pdb \ > ensemble_2.identity=95 \ > ensemble_2.copies_to_find=2 \ > component_2.mass=13410 \ > component_2.component_copies=2 > > > or > > > phenix.automr data=mydata.sca \ > ensemble_1.coords=domain1.pdb \ > ensemble_1.identity=95 \ > ensemble_1.copies_to_find=1 \ > component_1.mass=40579 \ > component_1.component_copies=2 \ > ensemble_2.coords=domain2.pdb \ > ensemble_2.identity=95 \ > ensemble_2.copies_to_find=1 \ > component_2.mass=13410 \ > component_2.component_copies=2 > > > essentially I'm not really using an ensemble of search models, I only > have a single PDB for each domain. So should ensemble_1.copies_to_find > and ensemble_2.copies_to_find be set to 1 or 2? > > > Thanks, > Scott > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > Scott Classen, Ph.D. > SIBYLS Beamline 12.3.1 > http://bl1231.als.lbl.gov > Advanced Light Source > Lawrence Berkeley National Laboratory > 1 Cyclotron Rd > MS6R2100 > Berkeley, CA 94720 > C) 510.206.4418 > O) 510.495.2697 > Beamline) 510.495.2134 > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > > > _______________________________________________ > phenixbb mailing list > phenixbb(a)phenix-online.org > http://www.phenix-online.org/mailman/listinfo/phenixbb >

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Using LigandFit to identify unknown density
by Katya Heldwein 28 Jan '10

28 Jan '10

Hi, I'd like to run LigandFit to identify a small molecule accounting for an unknown density. How do I do that, preferably, in a command-line mode? Katya -- Ekaterina Heldwein, Ph.D. Assistant Professor Department of Molecular Biology and Microbiology Tufts University School of Medicine 136 Harrison Ave Boston, MA 02111 phone: 617-636-0858 fax: 617-636-0337 e-mail: katya.heldwein(a)tufts.edu

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some sort of occupancy refinement
by Bryan W. Lepore 01 Jan '10

01 Jan '10

question is after the setup here : i have a ligand with multiple conformers. i gave each conformer a different chain label. refining occupancy for the overlapped parts kicks that part out of the density. i have remove_selection for the parts that are 1.0 and they seem OK. a single conformer stays in the density. i tried starting with and without site or occupancy refinement, no help. i do not want group occupancy refinement b/c some parts do not overlap - i.e. they "should" be occupancy 1.0 -- i tried it anyways with constrained_group =... to check. is the chain label an improper way to do this? -bryan p.s: Happy New Year with Blue Moon Eclipse (~10degW->180degE long. eastern HS)!

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high resolution Anomalous map
by vennila Natesan 31 Dec '09

31 Dec '09

Hello all... How do we create anomalous map using high resolution reflections? For example, if we have 2.2A resolution data (i.e 20-2.2A), i want to know how to create the anomalous map for the same dataset but from 2.4-2.2A resolution range. Vennila.

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phenix.refine change: support for residues on symmetry elements
by Ralf W. Grosse-Kunstleve 28 Dec '09

28 Dec '09

The current development version of phenix.refine (dev-268 or later) supports residues located on symmetry elements, e.g. SO4 on a three-fold axis. phenix.refine now computes structure factors slightly differently compared to older versions. The new rules are: - Atoms with occupancy == 1 are subject to automatic handling of the symmetry. Example: An atom near a three-fold axis (distance to symmetry copy <= 0.5 A) is moved onto the axis and constrained in refinement to stay on the axis. The "special position factor" (1/3 is this case) is taken into account internally. The factor does not appear in the occupancy. - Atoms with occupancy != 1 are assumed to take the special position factor into account in the occupancy. Automatic handling of the symmetry is turned off. Example: A disordered SO4 molecule near a three-fold axis should have occupancies of 0.33 for all atoms. - If all atoms in a residue have occupancies != 1, all nonbonded symmetry interactions between the atoms in the residue are disabled. These three rules are meant - to bring phenix.refine in line with other programs and the PDB. - "to do the right thing" in most cases without manual intervention. Please let me know if you see problems with the new way phenix.refine uses occupancies to determine special position constraints and exclusions for nonbonded symmetry interactions. Does anyone need atoms with partial occupancies but constrained to stay on a symmetry axis during refinement? Ralf

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Re: [phenixbb] Phaser SAD question
by Kitty Pattridge 24 Dec '09

24 Dec '09

"Randy J. Read" <rjr27(a)cam.ac.uk> wrote: >Dear Peter, > >I'm interested in your observation that you get better signal from an >anomalous difference map computed with density-modified phases than you get >with an LLG map using the MR model. Presumably the density modification >just started from the model phases as well? We've never tried that, so >we'll have to look into that. Unfortunately, you can't at the moment start >the LLG completion with a "model" specified through structure factors, >though this is on our to-do list. > >With the MR+SAD option, because it is iterative, there are sites found in >subsequent cycles (where the information from some of the anomalous >scatterers has become available) and you end up with a set of reliable >sites that can be significantly larger than the set obtained from the first >LLG map. Does your anomalous difference Fourier with density modified >phases give you a larger apparently reliable substructure than the >iterative completion? You could use phenix.emma to compare the two >substructures and see how much they have in common. > >You can indeed give Phaser the set of sites that you got from the anomalous >difference map. One way to choose the cutoff would be to see how deep the >deepest hole is (i.e. how many standard deviations the map goes in the >negative direction), and choose a larger number in the positive direction. >Or you could just use the peaks above 6-7 sigma. > >I'd be interested in hearing how you get on with this approach, off-line if >you prefer. > >Good luck and Happy Christmas! > >Randy Read > >On Dec 24 2009, Peter Grey wrote: > >>Dear Phenix Experts, >> >>I use the SAD+MR option in Phenix. The ASU is huge and the number of >>scatterres is in the few hundreds range. I try to minimize the number of >>runs of Phaser SAD+MR since they take long time on my computer and would >>appreciate your insight regarding the following : >> >> - I noticed that I get much higher signal and much larger number of sites >> if I use density modified phases to calculate the anomalous difference >> map. Is it possible to input these phases instead of the model to Phaser >> ? >> >> - If not, do you recommend providing Phaser with the list of sites found >> in this difference anomalous map. Should such a list include only the >> sites you can be sure of (say above 7 sigma) or all possible sites (say >> above 5 sigma) ? >> >> - Should I use the (peak height)/(sigma of map) as the first estimate of >> occupancy ? if so do I have to normalize it (strongest site has occupancy >> of 1) or can I leave the height/sigma values as they are ? >> >> >>Many thanks, >> >>Peter. >> > >_______________________________________________ >phenixbb mailing list >phenixbb(a)phenix-online.org >http://phenix-online.org/mailman/listinfo/phenixbb > >

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Re: [phenixbb] Phaser SAD question
by Kitty Pattridge 24 Dec '09

24 Dec '09

"Randy J. Read" <rjr27(a)cam.ac.uk> wrote: >Dear Peter, > >I'm interested in your observation that you get better signal from an >anomalous difference map computed with density-modified phases than you get >with an LLG map using the MR model. Presumably the density modification >just started from the model phases as well? We've never tried that, so >we'll have to look into that. Unfortunately, you can't at the moment start >the LLG completion with a "model" specified through structure factors, >though this is on our to-do list. > >With the MR+SAD option, because it is iterative, there are sites found in >subsequent cycles (where the information from some of the anomalous >scatterers has become available) and you end up with a set of reliable >sites that can be significantly larger than the set obtained from the first >LLG map. Does your anomalous difference Fourier with density modified >phases give you a larger apparently reliable substructure than the >iterative completion? You could use phenix.emma to compare the two >substructures and see how much they have in common. > >You can indeed give Phaser the set of sites that you got from the anomalous >difference map. One way to choose the cutoff would be to see how deep the >deepest hole is (i.e. how many standard deviations the map goes in the >negative direction), and choose a larger number in the positive direction. >Or you could just use the peaks above 6-7 sigma. > >I'd be interested in hearing how you get on with this approach, off-line if >you prefer. > >Good luck and Happy Christmas! > >Randy Read > >On Dec 24 2009, Peter Grey wrote: > >>Dear Phenix Experts, >> >>I use the SAD+MR option in Phenix. The ASU is huge and the number of >>scatterres is in the few hundreds range. I try to minimize the number of >>runs of Phaser SAD+MR since they take long time on my computer and would >>appreciate your insight regarding the following : >> >> - I noticed that I get much higher signal and much larger number of sites >> if I use density modified phases to calculate the anomalous difference >> map. Is it possible to input these phases instead of the model to Phaser >> ? >> >> - If not, do you recommend providing Phaser with the list of sites found >> in this difference anomalous map. Should such a list include only the >> sites you can be sure of (say above 7 sigma) or all possible sites (say >> above 5 sigma) ? >> >> - Should I use the (peak height)/(sigma of map) as the first estimate of >> occupancy ? if so do I have to normalize it (strongest site has occupancy >> of 1) or can I leave the height/sigma values as they are ? >> >> >>Many thanks, >> >>Peter. >> > >_______________________________________________ >phenixbb mailing list >phenixbb(a)phenix-online.org >http://phenix-online.org/mailman/listinfo/phenixbb > >

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Phaser SAD question
by Peter Grey 24 Dec '09

24 Dec '09

Dear Phenix Experts, I use the SAD+MR option in Phenix. The ASU is huge and the number of scatterres is in the few hundreds range. I try to minimize the number of runs of Phaser SAD+MR since they take long time on my computer and would appreciate your insight regarding the following : - I noticed that I get much higher signal and much larger number of sites if I use density modified phases to calculate the anomalous difference map. Is it possible to input these phases instead of the model to Phaser ? - If not, do you recommend providing Phaser with the list of sites found in this difference anomalous map. Should such a list include only the sites you can be sure of (say above 7 sigma) or all possible sites (say above 5 sigma) ? - Should I use the (peak height)/(sigma of map) as the first estimate of occupancy ? if so do I have to normalize it (strongest site has occupancy of 1) or can I leave the height/sigma values as they are ? Many thanks, Peter.

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