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pdb hierarchy
by Bradley Hintze 03 Dec '11

03 Dec '11

Hi Phenix, I have a hierarchy question. I was using the hierarchy and got something that I did not expect. when running this: pdb_io = pdb.input(pdbfile) hierarchy = pdb_io.construct_hierarchy() for model in hierarchy.models(): print model.id for chain in model.chains(): print ' ' + chain.id When I do this I expect the chains in pdbfile to be printed once for each model in pdbfile. However, when I ran this I got, for example, chain 'A' printed four times under the same model. Why is this? Thanks, Bradley

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Writing PDB
by Bradley Hintze 03 Dec '11

03 Dec '11

Hi again, I am trying to take a pdb and write out a new pdb with just a specified chain. I am trying to do this with the hierarchy but am unfamiliar with its functions How do I do this? Thanks, Bradley

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the Ming dial
by Dialing Pretty 03 Dec '11

03 Dec '11

Dear All, In the Ming dial, there is a occupancy (%), which indication of excellent , good, etc. Does it mean if I choose the "occupancy" of excellent, the rotamer outlier ratio will be lowered? My crystal has a resolution of 2.8, and I find no matter how I turn the dial, the original fits the map best. Currently my rotamer outlier is 8%, thus I need the way to have it solved. In addition, for Coot and Ming, which is much convenient to reduce rotamer outlier? I am looking forward to getting your reply. Cheers, Fenghui

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on the rotamer optimization
by Dialing Pretty 03 Dec '11

03 Dec '11

Dear All, Besides Coot and Ming, is any software or server which could further optimize the side chain outliers? I am looking forward to getting your reply. Cheers, Dialing

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solvent model in phenix.refine
by Weiergräber, Oliver H. 01 Dec '11

01 Dec '11

Hello, the ordered_solvent option in phenix.refine apparently uses these parameters by default: min_model_peak_dist = 1.8 max_model_peak_dist = 6.0 min_peak_peak_dist = 1.8 I was wondering about the justification for this (extremely relaxed) set of limits. As far as I know, the shortest hydrogen bonds (if defined as donor-acceptor distance) are about 2 A, and even these are considered exceptional and rare. Similarly, anything in excess of 3.5 A is quite unlikely to be significant energetically, so why use 6 A as an upper limit? Even if max_model_peak_dist was only meant to limit the extent of the outer solvent shell, there is no such thing as max_peak_peak_dist to avoid unreasonably long individual bonds. My personal suggestion would be a range of about 2.3 - 3.2 A for a significant hydrogen bond, with the lower limit exemplified by charged interactions (carboxyl-water or oxonium-water), which tend to be shorter - and stronger - than average. On the other hand, I do frequently observe elongated densities which, in accordance with the default parameters, are typically interpreted by phenix.refine as two water molecules about 2 A apart. So the question arises whether this is a realistic assumption, compared to a "sliding water" model in which the position of a single molecule is just ill-defined in a certain direction (due to a competition of adjacent binding sites for example)? Best regards, Oliver ================================================ PD Dr. Oliver H. Weiergräber Institute of Complex Systems ICS-6: Structural Biochemistry Tel.: +49 2461 61-2028 Fax: +49 2461 61-1448 ================================================ ------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------ Forschungszentrum Juelich GmbH 52425 Juelich Sitz der Gesellschaft: Juelich Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498 Vorsitzender des Aufsichtsrats: MinDirig Dr. Karl Eugen Huthmacher Geschaeftsfuehrung: Prof. Dr. Achim Bachem (Vorsitzender), Karsten Beneke (stellv. Vorsitzender), Prof. Dr.-Ing. Harald Bolt, Prof. Dr. Sebastian M. Schmidt ------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------

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Clashing alternative conformations
by Sozanne Solmaz 01 Dec '11

01 Dec '11

Dear all, I have the following problem: I have a homodimer of two protein chains A and B, which I refine in Phenix, and one residue has 2 alternate conformations (a and b) for each chain. If the residues of both chains A and B are in the alternative conformation b, they clash. However, I would expect that never both residues are in conformation b, and therefore only the combinations aa, ab and ba of alternative conformations exist. My problem is, that during the refinement, the two b conformations of the residues clash, which drives the clash-score of the overall structure to a very high value and repulsion pushes the two b-conformations apart during refinement, therefore I cannot model them properly. Is it possible in Phenix to define these two conformations as non-clashing and non-repulsive? Thank you, best regards, Sozanne Solmaz.

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"nproc" in phenix.refine
by Jonathan Elegheert 30 Nov '11

30 Nov '11

Dear all, I have a question regarding the "nproc" parameter in phenix.refine; We have the software installed on our university HPC cluster, which has nodes built up of 8 processors each. Submission works via a queuing system ("qsub"). I understand that compiling with OpenMP renders the nproc parameter disfunctional. Does this then imply that I will be limited to 1 node (8 processors) if compiled without OpenMP, since there is no "message passing" to other nodes? Or is there a way to make use of more of the available nodes, for example by compiling with OpenMP and then specifying many nodes with 1 processor? Best regards, Jonathan Elegheert PhD Student Unit for Structural Biology & Biophysics Ghent University jonathan.elegheert(a)ugent.be

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Nitric Oxide ligand keeps getting pushed far away from specified links in CIF
by Yarrow Madrona 29 Nov '11

29 Nov '11

Hello, I am having some trouble refining a structure with Nitric Oxide coordinated to the Heme Fe. I attempted to merge two Cif files. One for another ligand (CNL) and one for NO (NO.cif). I have saved the merged file as CinNO2.cif. In the defualt refinement I type the following into the command line: Mymodel.mtz mymodel.pdb CinNO2.cif Phenix refine runs fine without any errors but pushes the NO much further than the 1.9 angstrom specified by the links in the cif file. I have pasted the contents of the cif file below. The NO, Fe links are at the end of the file. Thank you for any help you can provide. -Yarrow # Files merged : Tue Oct 4 10:11:22 2011 # # CNL.cif # NO.cif # data_comp_list loop_ _chem_comp.id _chem_comp.three_letter_code _chem_comp.name _chem_comp.group _chem_comp.number_atoms_all _chem_comp.number_atoms_nh _chem_comp.desc_level CNL CNL Unknown ligand 29 11 . NO NO Unknown ligand 2 2 . # data_comp_CNL # loop_ _chem_comp_atom.comp_id _chem_comp_atom.atom_id _chem_comp_atom.type_symbol _chem_comp_atom.type_energy _chem_comp_atom.partial_charge _chem_comp_atom.x _chem_comp_atom.y _chem_comp_atom.z CNL C1 C CT . 55.3085 -9.1280 -43.0216 CNL C2 C CH2 . 55.6432 -10.5699 -43.1750 CNL C3 C CH2 . 54.6509 -11.3139 -43.9725 CNL C4 C CH1 . 53.4902 -10.4784 -44.3504 CNL C5 C CH2 . 53.9278 -9.3349 -45.0693 CNL C6 C CH2 . 54.8932 -8.4964 -44.3064 CNL C7 C CH3 . 56.3801 -8.3679 -42.3275 CNL C8 C CT . 52.9353 -9.9244 -43.0573 CNL C9 C CH3 . 52.3495 -11.0301 -42.2453 CNL C10 C CH3 . 51.8314 -8.9341 -43.2982 CNL O O O2 . 54.1049 -9.2461 -42.2221 # loop_ _chem_comp_bond.comp_id _chem_comp_bond.atom_id_1 _chem_comp_bond.atom_id_2 _chem_comp_bond.type _chem_comp_bond.value_dist _chem_comp_bond.value_dist_esd CNL C1 C2 single 1.488 0.020 CNL C1 C6 single 1.491 0.020 CNL C1 C7 single 1.486 0.020 CNL C1 O single 1.450 0.020 CNL C2 C3 single 1.475 0.020 CNL C3 C4 single 1.479 0.020 CNL C4 C5 single 1.420 0.020 CNL C4 C8 single 1.512 0.020 CNL C5 C6 single 1.489 0.020 CNL C8 C9 single 1.492 0.020 CNL C8 C10 single 1.502 0.020 CNL C8 O single 1.589 0.020 # loop_ _chem_comp_angle.comp_id _chem_comp_angle.atom_id_1 _chem_comp_angle.atom_id_2 _chem_comp_angle.atom_id_3 _chem_comp_angle.value_angle _chem_comp_angle.value_angle_esd CNL C3 C2 C1 113.16 3.000 CNL C5 C6 C1 112.56 3.000 CNL C8 O C1 110.85 3.000 CNL C6 C1 C2 112.60 3.000 CNL C7 C1 C2 112.43 3.000 CNL O C1 C2 99.48 3.000 CNL C4 C3 C2 112.41 3.000 CNL C5 C4 C3 110.02 3.000 CNL C8 C4 C3 106.05 3.000 CNL C6 C5 C4 113.20 3.000 CNL C9 C8 C4 109.75 3.000 CNL C10 C8 C4 111.96 3.000 CNL O C8 C4 109.61 3.000 CNL C8 C4 C5 104.53 3.000 CNL C7 C1 C6 112.76 3.000 CNL O C1 C6 106.18 3.000 CNL O C1 C7 112.51 3.000 CNL C10 C8 C9 106.70 3.000 CNL O C8 C9 108.62 3.000 CNL O C8 C10 110.10 3.000 # 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 CNL Var_01 C4 C8 O C1 10.40 30.0 3 CNL Var_02 C9 C8 O C1 130.31 30.0 3 CNL Var_03 C10 C8 O C1 -113.19 30.0 3 # loop_ _chem_comp_chir.comp_id _chem_comp_chir.id _chem_comp_chir.atom_id_centre _chem_comp_chir.atom_id_1 _chem_comp_chir.atom_id_2 _chem_comp_chir.atom_id_3 _chem_comp_chir.volume_sign CNL chir_01 C1 C6 C7 O both CNL chir_02 C4 C3 C5 C8 both # data_comp__NO # loop_ _chem_comp_atom.comp_id _chem_comp_atom.atom_id _chem_comp_atom.type_symbol _chem_comp_atom.type_energy _chem_comp_atom.partial_charge _chem_comp_atom.x _chem_comp_atom.y _chem_comp_atom.z NO N N N . -5.7690 4.3760 32.3600 NO O O O . -4.8990 5.2460 32.3600 # loop_ _chem_comp_bond.comp_id _chem_comp_bond.atom_id_1 _chem_comp_bond.atom_id_2 _chem_comp_bond.type _chem_comp_bond.value_dist _chem_comp_bond.value_dist_esd NO N O double 1.150 0.02 # data_link_list loop_ _chem_link.id _chem_link.comp_id_1 _chem_link.mod_id_1 _chem_link.group_comp_1 _chem_link.comp_id_2 _chem_link.mod_id_2 _chem_link.group_comp_2 _chem_link.name HEM-CYS HEM . . CYS . . bond_CYS-SG_=_HEM-FE NO -HEM HEM . . NO . . bond_HEM-FE_=_NO-N # data_link_HEM-CYS # loop_ _chem_link_bond.link_id _chem_link_bond.atom_1_comp_id _chem_link_bond.atom_id_1 _chem_link_bond.atom_2_comp_id _chem_link_bond.atom_id_2 _chem_link_bond.type _chem_link_bond.value_dist _chem_link_bond.value_dist_esd HEM-CYS 1 FE 2 SG . 2.300000 0.020 # loop_ _chem_link_angle.link_id _chem_link_angle.atom_1_comp_id _chem_link_angle.atom_id_1 _chem_link_angle.atom_2_comp_id _chem_link_angle.atom_id_2 _chem_link_angle.atom_3_comp_id _chem_link_angle.atom_id_3 _chem_link_angle.value_angle _chem_link_angle.value_angle_esd HEM-CYS 2 SG 1 FE 1 NC 109.471221 3.000 HEM-CYS 1 FE 2 SG 2 CB 109.471221 3.000 # data_link_NO -HEM # loop_ _chem_link_bond.link_id _chem_link_bond.atom_1_comp_id _chem_link_bond.atom_id_1 _chem_link_bond.atom_2_comp_id _chem_link_bond.atom_id_2 _chem_link_bond.type _chem_link_bond.value_dist _chem_link_bond.value_dist_esd NO -HEM 1 N 2 FE . 1.900000 0.020 # loop_ _chem_link_angle.link_id _chem_link_angle.atom_1_comp_id _chem_link_angle.atom_id_1 _chem_link_angle.atom_2_comp_id _chem_link_angle.atom_id_2 _chem_link_angle.atom_3_comp_id _chem_link_angle.atom_id_3 _chem_link_angle.value_angle _chem_link_angle.value_angle_esd NO -HEM 2 FE 1 N 1 O 140 3.000 NO -HEM 1 N 2 FE 2 NC 103 3.000 -- Yarrow Madrona Graduate Student Molecular Biology and Biochemistry Dept. University of California, Irvine Natural Sciences I, Rm 2403 Irvine, CA 92697

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Mn - O distances
by Timothy Springer 29 Nov '11

29 Nov '11

Hi, We are refining structures with Ca binding sites that are replaced by Mn. Using the coordination restraints in Phenix (distance only) obtained with phenix.metal_coordination, we wind up with the ligands coming somewhat too close, so there is positive density on the opposite side of the ligating residue from the metal. We may have a series of problems, including incomplete replacement of Ca by Mn. However, the bigger issue I want to address is coordination number. In the work by Shannon and Prewitt, such as Acta Cryst. B25, 925, metal oxides are examined, and the point is made that the Mn-O distance with a coordination number of 6 is shorter than for 7. Ca commonly has either 6 or 7 ligands, and with 7 ligands (most common) the O cannot squeeze as tightly together and are farther away from Ca. Mn more commonly has 6 ligands, but can have 7. What are the distance restraints in Phenix based on? They seem similar to those in Harding MM, Acta Cryst D62, 678 (2006). This paper lumps measurements for different coordination numbers together for Mn-O and Ca-O distances, but not for Co, Cu, and Zn. It does seem to help to add metal ion restraints in Phenix. Things don't seem to come out as well without them. Would it be helpful to treat 6 and 7-coordinate metals differently? Or should we just loosen the restraints? How does Refmac treat metals? One does not need to add restraints in its case. With my best regards, Tim Timothy A. Springer, Ph.D. Latham Family Professor of Biological Chemistry and Molecular Pharmacology Harvard Medical School http://idi.harvard.edu/springer Immune Disease Institute springer(a)idi.harvard.edu Program in Cellular and Molecular Medicine, Dept. Medicine Div. Hematology Children's Hospital Boston 3 Blackfan Circle, Rm 3103 phone: 617-713-8200 Boston MA 02115 fax: 617-713-8232

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Metal restraints at special position
by Yuri 28 Nov '11

28 Nov '11

I have a Mg2+ coordinated to 4 waters and 2 side chains. Some of the waters are at special postions. I generated the restraints file using "phenix.metal_cordination input.pdb" When I run refine with my .edits restraints file it crashes due to the special position. How do I handle this? Best, -- Yuri Pompeu

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