The bond angles are taken from the input file, so its a good idea to
remove them in the initial rounds of refinement.
Nigel
On Wed, Aug 31, 2011 at 10:05 AM, Zhang yu
Dear all, I have been stuck in the problem for a while. I appreciate any suggestions. I have two zinc binding domain in my 3A structure which are Cys4 type. The geometry is OK for one domain, but it is not refined properly in the other one. The problems during phenix refinement are 1. Zinc is always refined to position ~0.5A off from its correct position 2. The refined bond lengths of four Cys-Zn are all below 2.3 3. Sometimes, distances between SG atoms of nearby cysteines are too close, and coot just connect them as disulfate bond. 4. Sometimes, I get the following message showing that all bond angles are outliers with >8 sigmas, I listed part of the outliers.
Top angle outliers (sorted by deviation): atoms ideal model difference deviation (sigma) ---------------------------------------------------------------------------- SG CYS D1204 57.894 104.470 46.576 9.32 ZN ZN D2001 SG CYS D1112 SG CYS D1201 50.842 92.496 41.654 8.33 ZN ZN D2001 SG CYS D1204 SG CYS D1204 126.952 92.496 -34.455 -6.89 ZN ZN D2001 SG CYS D1201 SG CYS D1201 52.183 86.105 33.922 6.78 ZN ZN D2001 SG CYS D1112 SG CYS D1194 152.275 119.729 -32.546 -6.51 ZN ZN D2001 SG CYS D1112 SG CYS D1112 89.273 119.729 30.456 6.09 ZN ZN D2001 SG CYS D1194 I also post my metal.edit file for refinement refinement.geometry_restraints.edits { bond { action = *add atom_selection_1 = name ZN and chain D and resname ZN and resseq 2001 atom_selection_2 = name SG and chain D and resname CYS and resseq 1201 distance_ideal = 2.310000 sigma = 0.100 } } refinement.geometry_restraints.edits { bond { action = *add atom_selection_1 = name ZN and chain D and resname ZN and resseq 2001 atom_selection_2 = name SG and chain D and resname CYS and resseq 1194 distance_ideal = 2.310000 sigma = 0.100 } } refinement.geometry_restraints.edits { bond { action = *add atom_selection_1 = name ZN and chain D and resname ZN and resseq 2001 atom_selection_2 = name SG and chain D and resname CYS and resseq 1112 distance_ideal = 2.310000 sigma = 0.100 } } refinement.geometry_restraints.edits { bond { action = *add atom_selection_1 = name ZN and chain D and resname ZN and resseq 2001 atom_selection_2 = name SG and chain D and resname CYS and resseq 1204 distance_ideal = 2.310000 sigma = 0.100 } } refinement.geometry_restraints.edits { angle { action = *add atom_selection_1 = name SG and chain D and resname CYS and resseq 1194 atom_selection_2 = name ZN and chain D and resname ZN and resseq 2001 atom_selection_3 = name SG and chain D and resname CYS and resseq 1201 angle_ideal = 112.172178 sigma = 5 } } refinement.geometry_restraints.edits { angle { action = *add atom_selection_1 = name SG and chain D and resname CYS and resseq 1112 atom_selection_2 = name ZN and chain D and resname ZN and resseq 2001 atom_selection_3 = name SG and chain D and resname CYS and resseq 1201 angle_ideal = 87.092184 sigma = 5 } } refinement.geometry_restraints.edits { angle { action = *add atom_selection_1 = name SG and chain D and resname CYS and resseq 1112 atom_selection_2 = name ZN and chain D and resname ZN and resseq 2001 atom_selection_3 = name SG and chain D and resname CYS and resseq 1194 angle_ideal = 118.116518 sigma = 5 } } refinement.geometry_restraints.edits { angle { action = *add atom_selection_1 = name SG and chain D and resname CYS and resseq 1204 atom_selection_2 = name ZN and chain D and resname ZN and resseq 2001 atom_selection_3 = name SG and chain D and resname CYS and resseq 1201 angle_ideal = 91.677138 sigma = 5 } } refinement.geometry_restraints.edits { angle { action = *add atom_selection_1 = name SG and chain D and resname CYS and resseq 1204 atom_selection_2 = name ZN and chain D and resname ZN and resseq 2001 atom_selection_3 = name SG and chain D and resname CYS and resseq 1194 angle_ideal = 130.829256 sigma = 5 } } refinement.geometry_restraints.edits { angle { action = *add atom_selection_1 = name SG and chain D and resname CYS and resseq 1204 atom_selection_2 = name ZN and chain D and resname ZN and resseq 2001 atom_selection_3 = name SG and chain D and resname CYS and resseq 1112 angle_ideal = 104.886672 sigma = 5 } }
Questions, 1. Why the ideal bond angle are different in the metal.edit file and final model ? How does phenix determine the ideal bond_angle? For example, in the metal.edit file atom_selection_1 = name SG and chain D and resname CYS and resseq 1204 atom_selection_2 = name ZN and chain D and resname ZN and resseq 2001 atom_selection_3 = name SG and chain D and resname CYS and resseq 1112 The angle_ideal = 104.886672 But in the final model
atoms ideal model difference deviation (sigma) ---------------------------------------------------------------------------- SG CYS D1204 57.894 104.470 46.576 9.32 ZN ZN D2001 SG CYS D1112 2. Do I need to put the following LINK in the pdb header to run refinement? LINK ZN ZN D2001 SG CYS D1201 1555 1555 2.34 LINK ZN ZN D2001 SG CYS D1112 1555 1555 2.33 LINK ZN ZN D2001 SG CYS D1194 1555 1555 2.38 LINK ZN ZN D2001 SG CYS D1204 1555 1555 2.37 3. After phenix refinement, the output pdb doesn't contain these LINK lines no matter what the inpout pdb is. Does phenix_refine use these restrains of LINK lines? Thanks. Yu Zhang Postdoc fellow Rutgers University _______________________________________________ phenixbb mailing list [email protected] http://phenix-online.org/mailman/listinfo/phenixbb
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