WHAT IF Check report

This file was created 2012-01-04 from WHAT_CHECK output by a conversion script. If you are new to WHAT_CHECK, please study the pdbreport pages. There also exists a legend to the output.

Please note that you are looking at an abridged version of the output (all checks that gave normal results have been removed from this report). You can have a look at the Full report instead.

Verification log for pdb1lzv.ent

Non-validating, descriptive output paragraph

Note: Ramachandran plot

In this Ramachandran plot x-signs represent glycines, squares represent prolines, and plus-signs represent the other residues. If too many plus- signs fall outside the contoured areas then the molecule is poorly refined (or worse). Proline can only occur in the narrow region around phi=-60 that also falls within the other contour islands.

In a colour picture, the residues that are part of a helix are shown in blue, strand residues in red. Preferred regions for helical residues are drawn in blue, for strand residues in red, and for all other residues in green. A full explanation of the Ramachandran plot together with a series of examples can be found at the WHAT_CHECK website.

Chain identifier: A

Coordinate problems, unexpected atoms, B-factor and occupancy checks

Warning: What type of B-factor?

WHAT IF does not yet know well how to cope with B-factors in case TLS has been used. It simply assumes that the B-factor listed on the ATOM and HETATM cards are the total B-factors. When TLS refinement is used that assumption sometimes is not correct. TLS seems not mentioned in the header of the PDB file. But anyway, if WHAT IF complains about your B-factors, and you think that they are OK, then check for TLS related B-factor problems first.

Obviously, the temperature at which the X-ray data was collected has some importance too:

Crystal temperature (K) :293.000

Note: B-factor plot

The average atomic B-factor per residue is plotted as function of the residue number.

Chain identifier: A

Nomenclature related problems

Warning: Glutamic acid convention problem

The glutamic acid residues listed in the table below have their chi-3 outside the -90.0 to 90.0 range, or their proton on OE1 instead of OE2.

  10 GLU   (  14-)  A
  22 GLU   (  26-)  A
 182 GLU   ( 187-)  A

Geometric checks

Error: Nomenclature error(s)

Checking for a hand-check. WHAT IF has over the course of this session already corrected the handedness of atoms in several residues. These were administrative corrections. These residues are listed here.

  10 GLU   (  14-)  A
  22 GLU   (  26-)  A
 182 GLU   ( 187-)  A

Error: Tau angle problems

The side chains of the residues listed in the table below contain a tau angle (N-Calpha-C) that was found to deviate from te expected value by more than 4.0 times the expected standard deviation. The number in the table is the number of standard deviations this RMS value deviates from the expected value.

 202 VAL   ( 207-)  A    4.70

Torsion-related checks

Warning: Torsion angle evaluation shows unusual residues

The residues listed in the table below contain bad or abnormal torsion angles.

These scores give an impression of how `normal' the torsion angles in protein residues are. All torsion angles except omega are used for calculating a `normality' score. Average values and standard deviations were obtained from the residues in the WHAT IF database. These are used to calculate Z-scores. A residue with a Z-score of below -2.0 is poor, and a score of less than -3.0 is worrying. For such residues more than one torsion angle is in a highly unlikely position.

  79 PRO   (  83-)  A    -2.8
 171 PHE   ( 176-)  A    -2.4
  46 SER   (  50-)  A    -2.2
  56 LEU   (  60-)  A    -2.1
 146 GLY   ( 151-)  A    -2.0

Warning: Backbone evaluation reveals unusual conformations

The residues listed in the table below have abnormal backbone torsion angles.

Residues with `forbidden' phi-psi combinations are listed, as well as residues with unusual omega angles (deviating by more than 3 sigma from the normal value). Please note that it is normal if about 5 percent of the residues is listed here as having unusual phi-psi combinations.

  25 SER   (  29-)  A  PRO omega poor
  60 HIS   (  64-)  A  Poor phi/psi
 106 ASP   ( 110-)  A  Poor phi/psi
 107 LYS   ( 111-)  A  Poor phi/psi
 124 GLY   ( 129-)  A  Poor phi/psi
 173 ASN   ( 178-)  A  Poor phi/psi
 196 PRO   ( 201-)  A  PRO omega poor
 247 LYS   ( 252-)  A  Poor phi/psi
 chi-1/chi-2 correlation Z-score : -2.301

Warning: Unusual backbone conformations

For the residues listed in the table below, the backbone formed by itself and two neighbouring residues on either side is in a conformation that is not seen very often in the database of solved protein structures. The number given in the table is the number of similar backbone conformations in the database with the same amino acid in the centre.

For this check, backbone conformations are compared with database structures using C-alpha superpositions with some restraints on the backbone oxygen positions.

A residue mentioned in the table can be part of a strange loop, or there might be something wrong with it or its directly surrounding residues. There are a few of these in every protein, but in any case it is worth looking at!

   3 HIS   (   7-)  A      0
   6 HIS   (  10-)  A      0
  15 ASP   (  19-)  A      0
  16 PHE   (  20-)  A      0
  20 LYS   (  24-)  A      0
  23 ARG   (  27-)  A      0
  24 GLN   (  28-)  A      0
  25 SER   (  29-)  A      0
  46 SER   (  50-)  A      0
  48 ASP   (  52-)  A      0
  50 ALA   (  54-)  A      0
  58 ASN   (  62-)  A      0
  60 HIS   (  64-)  A      0
  68 ASP   (  72-)  A      0
  69 SER   (  73-)  A      0
  71 ASP   (  75-)  A      0
  72 LYS   (  76-)  A      0
  73 ALA   (  77-)  A      0
  76 LYS   (  80-)  A      0
  79 PRO   (  83-)  A      0
  81 ASP   (  85-)  A      0
  88 GLN   (  92-)  A      0
  95 SER   (  99-)  A      0
  99 GLN   ( 103-)  A      0
 103 HIS   ( 107-)  A      0
And so on for a total of 115 lines.

Warning: Omega angles too tightly restrained

The omega angles for trans-peptide bonds in a structure are expected to give a gaussian distribution with the average around +178 degrees and a standard deviation around 5.5 degrees. These expected values were obtained from very accurately determined structures. Many protein structures are too tightly restrained. This seems to be the case with the current structure too, as the observed standard deviation is below 4.0 degrees.

Standard deviation of omega values : 1.407

Warning: Backbone oxygen evaluation

The residues listed in the table below have an unusual backbone oxygen position.

For each of the residues in the structure, a search was performed to find 5-residue stretches in the WHAT IF database with superposable C-alpha coordinates, and some restraining on the neighbouring backbone oxygens.

In the following table the RMS distance between the backbone oxygen positions of these matching structures in the database and the position of the backbone oxygen atom in the current residue is given. If this number is larger than 1.5 a significant number of structures in the database show an alternative position for the backbone oxygen. If the number is larger than 2.0 most matching backbone fragments in the database have the peptide plane flipped. A manual check needs to be performed to assess whether the experimental data can support that alternative as well. The number in the last column is the number of database hits (maximum 80) used in the calculation. It is "normal" that some glycine residues show up in this list, but they are still worth checking!

 230 GLY   ( 235-)  A   1.56   14

Bump checks

Error: Abnormally short interatomic distances

The pairs of atoms listed in the table below have an unusually short interactomic distance; each bump is listed in only one direction.

The contact distances of all atom pairs have been checked. Two atoms are said to `bump' if they are closer than the sum of their Van der Waals radii minus 0.40 Angstrom. For hydrogen bonded pairs a tolerance of 0.55 Angstrom is used. The first number in the table tells you how much shorter that specific contact is than the acceptable limit. The second distance is the distance between the centres of the two atoms. Although we believe that two water atoms at 2.4 A distance are too close, we only report water pairs that are closer than this rather short distance.

The last text-item on each line represents the status of the atom pair. If the final column contains the text 'HB', the bump criterion was relaxed because there could be a hydrogen bond. Similarly relaxed criteria are used for 1-3 and 1-4 interactions (listed as 'B2' and 'B3', respectively). BL indicates that the B-factors of the clashing atoms have a low B-factor thereby making this clash even more worrisome. INTRA and INTER indicate whether the clashes are between atoms in the same asymmetric unit, or atoms in symmetry related asymmetric units, respectively.

  71 ASP   (  75-)  A      OD1 <->   85 ARG   (  89-)  A      NE     0.43    2.27  INTRA
 153 GLN   ( 158-)  A      NE2 <->  156 VAL   ( 161-)  A      CG2    0.21    2.89  INTRA BL
  11 HIS   (  15-)  A      ND1 <->   14 LYS   (  18-)  A      NZ     0.16    2.84  INTRA
  99 GLN   ( 103-)  A      NE2 <->  238 ASP   ( 243-)  A      OD1    0.15    2.55  INTRA BL
 228 GLY   ( 233-)  A      N   <->  231 GLU   ( 236-)  A      OE1    0.15    2.55  INTRA
 242 PRO   ( 247-)  A      O   <->  244 GLN   ( 249-)  A      NE2    0.15    2.55  INTRA BL
 182 GLU   ( 187-)  A      N   <->  258 HOH   ( 341 )  A      O      0.13    2.57  INTRA
 113 GLU   ( 117-)  A      OE2 <->  115 HIS   ( 119-)  A      NE2    0.13    2.57  INTRA BL
  47 TYR   (  51-)  A      OH  <->  118 HIS   ( 122-)  A      NE2    0.11    2.59  INTRA
  54 ARG   (  58-)  A      O   <->   65 GLU   (  69-)  A      N      0.10    2.60  INTRA BL
  71 ASP   (  75-)  A      OD1 <->   85 ARG   (  89-)  A      NH2    0.08    2.62  INTRA
 109 LYS   ( 113-)  A      N   <->  258 HOH   ( 329 )  A      O      0.07    2.63  INTRA
 191 GLY   ( 196-)  A      N   <->  202 VAL   ( 207-)  A      O      0.07    2.63  INTRA BL
 103 HIS   ( 107-)  A      N   <->  113 GLU   ( 117-)  A      OE1    0.06    2.64  INTRA BL
 228 GLY   ( 233-)  A      O   <->  230 GLY   ( 235-)  A      N      0.06    2.64  INTRA
  71 ASP   (  75-)  A      OD1 <->   85 ARG   (  89-)  A      CZ     0.06    2.74  INTRA
  95 SER   (  99-)  A      N   <->   96 LEU   ( 100-)  A      N      0.05    2.55  INTRA BL
  53 LEU   (  57-)  A      N   <->   65 GLU   (  69-)  A      O      0.05    2.65  INTRA BL
 247 LYS   ( 252-)  A      CB  <->  248 ASN   ( 253-)  A      N      0.04    2.66  INTRA B3
  36 TYR   (  40-)  A      CE2 <->   38 PRO   (  42-)  A      CG     0.04    3.16  INTRA
  63 ASN   (  67-)  A      ND2 <->   88 GLN   (  92-)  A      NE2    0.04    2.81  INTRA BL
 120 ASN   ( 124-)  A      N   <->  135 GLY   ( 140-)  A      O      0.04    2.66  INTRA BL
 202 VAL   ( 207-)  A      CG1 <->  203 THR   ( 208-)  A      N      0.04    2.96  INTRA BL
 238 ASP   ( 243-)  A      CA  <->  240 TRP   ( 245-)  A      NE1    0.03    3.07  INTRA BL
  18 ILE   (  22-)  A      O   <->   21 GLY   (  25-)  A      N      0.03    2.67  INTRA
  17 PRO   (  21-)  A      C   <->   19 ALA   (  23-)  A      N      0.03    2.87  INTRA BL
 196 PRO   ( 201-)  A      CA  <->  198 LEU   ( 203-)  A      N      0.03    3.07  INTRA BL
 175 ASP   ( 180-)  A      OD1 <->  177 ARG   ( 182-)  A      N      0.02    2.68  INTRA
 224 LEU   ( 229-)  A      O   <->  236 MET   ( 241-)  A      N      0.02    2.68  INTRA BL
  79 PRO   (  83-)  A      N   <->   80 LEU   (  84-)  A      N      0.01    2.59  INTRA B3
  26 PRO   (  30-)  A      O   <->  244 GLN   ( 249-)  A      N      0.01    2.69  INTRA BL
  51 THR   (  55-)  A      N   <->  258 HOH   ( 317 )  A      O      0.01    2.69  INTRA
 140 GLY   ( 145-)  A      N   <->  205 ILE   ( 210-)  A      O      0.01    2.69  INTRA BL

Packing, accessibility and threading

Note: Inside/Outside RMS Z-score plot

The Inside/Outside distribution normality RMS Z-score over a 15 residue window is plotted as function of the residue number. High areas in the plot (above 1.5) indicate unusual inside/outside patterns.

Chain identifier: A

Warning: Abnormal packing environment for some residues

The residues listed in the table below have an unusual packing environment.

The packing environment of the residues is compared with the average packing environment for all residues of the same type in good PDB files. A low packing score can indicate one of several things: Poor packing, misthreading of the sequence through the density, crystal contacts, contacts with a co-factor, or the residue is part of the active site. It is not uncommon to see a few of these, but in any case this requires further inspection of the residue.

   6 HIS   (  10-)  A      -6.34
  96 LEU   ( 100-)  A      -5.17

Note: Quality value plot

The quality value smoothed over a 10 residue window is plotted as function of the residue number. Low areas in the plot (below -2.0) indicate unusual packing.

Chain identifier: A

Note: Second generation quality Z-score plot

The second generation quality Z-score smoothed over a 10 residue window is plotted as function of the residue number. Low areas in the plot (below -1.3) indicate unusual packing.

Chain identifier: A

Water, ion, and hydrogenbond related checks

Error: HIS, ASN, GLN side chain flips

Listed here are Histidine, Asparagine or Glutamine residues for which the orientation determined from hydrogen bonding analysis are different from the assignment given in the input. Either they could form energetically more favourable hydrogen bonds if the terminal group was rotated by 180 degrees, or there is no assignment in the input file (atom type 'A') but an assignment could be made. Be aware, though, that if the topology could not be determined for one or more ligands, then this option will make errors.

 173 ASN   ( 178-)  A

Warning: Buried unsatisfied hydrogen bond donors

The buried hydrogen bond donors listed in the table below have a hydrogen atom that is not involved in a hydrogen bond in the optimized hydrogen bond network.

Hydrogen bond donors that are buried inside the protein normally use all of their hydrogens to form hydrogen bonds within the protein. If there are any non hydrogen bonded buried hydrogen bond donors in the structure they will be listed here. In very good structures the number of listed atoms will tend to zero.

Waters are not listed by this option.

  27 VAL   (  31-)  A      N
  70 GLN   (  74-)  A      N
  95 SER   (  99-)  A      N
  96 LEU   ( 100-)  A      N
 128 LYS   ( 133-)  A      NZ
 160 ASP   ( 165-)  A      N
 172 THR   ( 177-)  A      OG1
 195 THR   ( 200-)  A      N
 199 LEU   ( 204-)  A      N
 216 GLU   ( 221-)  A      N
 225 ASN   ( 230-)  A      ND2
 239 ASN   ( 244-)  A      ND2
 240 TRP   ( 245-)  A      N
 255 PHE   ( 260-)  A      N
Only metal coordination for   92 HIS  (  96-) A      NE2

Warning: Unusual water packing

We implemented the ion valence determination method of Brown and Wu [REF] similar to Nayal and Di Cera [REF] and Mueller, Koepke and Sheldrick [REF]. It must be stated that the validation of ions in PDB files is very difficult. Ideal ion-ligand distances often differ no more than 0.1 Angstrom, and in a 2.0 Angstrom resolution structure 0.1 Angstrom is not very much. Nayal and Di Cera showed that this method nevertheless has great potential for detecting water molecules that actually should be metal ions. The method has not been extensively validated, though. Part of our implementation (comparing waters with multiple ion types) is even fully new and despite that we see it work well in the few cases that are trivial, we must emphasize that this method is untested.

The score listed is the valency score. This number should be close to (preferably a bit above) 1.0 for the suggested ion to be a likely alternative for the water molecule. Ions listed in brackets are good alternate choices. *1 indicates that the suggested ion-type has been observed elsewhere in the PDB file too. *2 indicates that the suggested ion-type has been observed in the REMARK 280 cards of the PDB file. Ion-B and ION-B indicate that the B-factor of this water is high, or very high, respectively. H2O-B indicates that the B-factors of atoms that surround this water/ion are suspicious. See: swift.cmbi.ru.nl/teach/theory/ for a detailed explanation.

 258 HOH   ( 338 )  A      O  0.94  K  4

Warning: Possible wrong residue type

The residues listed in the table below have a weird environment that cannot be improved by rotamer flips. This can mean one of three things, non of which WHAT CHECK really can do much about. 1) The side chain has actually another rotamer than is present in the PDB file; 2) A counter ion is present in the structure but is not given in the PDB file; 3) The residue actually is another amino acid type. The annotation 'Alt-rotamer' indicates that WHAT CHECK thinks you might want to find an alternate rotamer for this residue. The annotation 'Sym-induced' indicates that WHAT CHECK believes that symmetry contacts might have something to do with the difficulties of this residue's side chain. Determination of these two annotations is difficult, so their absence is less meaningful than their presence. The annotation Ligand-bound indicates that a ligand seems involved with this residue. In nine of ten of these cases this indicates that the ligand is causing the weird situation rather than the residue.

  10 GLU   (  14-)  A   H-bonding suggests Gln
  28 ASP   (  32-)  A   H-bonding suggests Asn; but Alt-Rotamer
 157 ASP   ( 162-)  A   H-bonding suggests Asn; but Alt-Rotamer

Final summary

Note: Summary report for users of a structure

This is an overall summary of the quality of the structure as compared with current reliable structures. This summary is most useful for biologists seeking a good structure to use for modelling calculations.

The second part of the table mostly gives an impression of how well the model conforms to common refinement restraint values. The first part of the table shows a number of global quality indicators.


Structure Z-scores, positive is better than average:

  1st generation packing quality :  -0.411
  2nd generation packing quality :   0.550
  Ramachandran plot appearance   :  -2.042
  chi-1/chi-2 rotamer normality  :  -2.301
  Backbone conformation          :  -1.080

RMS Z-scores, should be close to 1.0:
  Bond lengths                   :   0.298 (tight)
  Bond angles                    :   0.663 (tight)
  Omega angle restraints         :   0.256 (tight)
  Side chain planarity           :   0.253 (tight)
  Improper dihedral distribution :   0.593
  B-factor distribution          :   0.512
  Inside/Outside distribution    :   0.939

Note: Summary report for depositors of a structure

This is an overall summary of the quality of the X-ray structure as compared with structures solved at similar resolutions. This summary can be useful for a crystallographer to see if the structure makes the best possible use of the data. Warning. This table works well for structures solved in the resolution range of the structures in the WHAT IF database, which is presently (summer 2008) mainly 1.1 - 1.3 Angstrom. The further the resolution of your file deviates from this range the more meaningless this table becomes.

The second part of the table mostly gives an impression of how well the model conforms to common refinement restraint values. The first part of the table shows a number of global quality indicators, which have been calibrated against structures of similar resolution.

Resolution found in PDB file : 2.30


Structure Z-scores, positive is better than average:

  1st generation packing quality :   0.2
  2nd generation packing quality :   1.0
  Ramachandran plot appearance   :  -0.5
  chi-1/chi-2 rotamer normality  :  -0.8
  Backbone conformation          :  -1.0

RMS Z-scores, should be close to 1.0:
  Bond lengths                   :   0.298 (tight)
  Bond angles                    :   0.663 (tight)
  Omega angle restraints         :   0.256 (tight)
  Side chain planarity           :   0.253 (tight)
  Improper dihedral distribution :   0.593
  B-factor distribution          :   0.512
  Inside/Outside distribution    :   0.939
==============

WHAT IF
    G.Vriend,
      WHAT IF: a molecular modelling and drug design program,
    J. Mol. Graph. 8, 52--56 (1990).

WHAT_CHECK (verification routines from WHAT IF)
    R.W.W.Hooft, G.Vriend, C.Sander and E.E.Abola,
      Errors in protein structures
    Nature 381, 272 (1996).
    (see also http://swift.cmbi.ru.nl/gv/whatcheck for a course and extra inform

Bond lengths and angles, protein residues
    R.Engh and R.Huber,
      Accurate bond and angle parameters for X-ray protein structure
      refinement,
    Acta Crystallogr. A47, 392--400 (1991).

Bond lengths and angles, DNA/RNA
    G.Parkinson, J.Voitechovsky, L.Clowney, A.T.Bruenger and H.Berman,
      New parameters for the refinement of nucleic acid-containing structures
    Acta Crystallogr. D52, 57--64 (1996).

DSSP
    W.Kabsch and C.Sander,
      Dictionary of protein secondary structure: pattern
      recognition of hydrogen bond and geometrical features
    Biopolymers 22, 2577--2637 (1983).

Hydrogen bond networks
    R.W.W.Hooft, C.Sander and G.Vriend,
      Positioning hydrogen atoms by optimizing hydrogen bond networks in
      protein structures
    PROTEINS, 26, 363--376 (1996).

Matthews' Coefficient
    B.W.Matthews
      Solvent content of Protein Crystals
    J. Mol. Biol. 33, 491--497 (1968).

Protein side chain planarity
    R.W.W. Hooft, C. Sander and G. Vriend,
      Verification of protein structures: side-chain planarity
    J. Appl. Cryst. 29, 714--716 (1996).

Puckering parameters
    D.Cremer and J.A.Pople,
      A general definition of ring puckering coordinates
    J. Am. Chem. Soc. 97, 1354--1358 (1975).

Quality Control
    G.Vriend and C.Sander,
      Quality control of protein models: directional atomic
      contact analysis,
    J. Appl. Cryst. 26, 47--60 (1993).

Ramachandran plot
    G.N.Ramachandran, C.Ramakrishnan and V.Sasisekharan,
      Stereochemistry of Polypeptide Chain Conformations
    J. Mol. Biol. 7, 95--99 (1963).

Symmetry Checks
    R.W.W.Hooft, C.Sander and G.Vriend,
      Reconstruction of symmetry related molecules from protein
      data bank (PDB) files
    J. Appl. Cryst. 27, 1006--1009 (1994).

Ion Checks
    I.D.Brown and K.K.Wu,
      Empirical Parameters for Calculating Cation-Oxygen Bond Valences
    Acta Cryst. B32, 1957--1959 (1975).

    M.Nayal and E.Di Cera,
      Valence Screening of Water in Protein Crystals Reveals Potential Na+
      Binding Sites
    J.Mol.Biol. 256 228--234 (1996).

    P.Mueller, S.Koepke and G.M.Sheldrick,
      Is the bond-valence method able to identify metal atoms in protein
      structures?
    Acta Cryst. D 59 32--37 (2003).

Checking checks
    K.Wilson, C.Sander, R.W.W.Hooft, G.Vriend, et al.
      Who checks the checkers
    J.Mol.Biol. (1998) 276,417-436.