WHAT IF Check report

This file was created 2012-01-25 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 pdb2f5q.ent

Checks that need to be done early-on in validation

Warning: Problem detected upon counting molecules and matrices

The parameter Z as given on the CRYST card represents the molecular multiplicity in the crystallographic cell. Normally, Z equals the number of matrices of the space group multiplied by the number of NCS relations. The value of Z is multiplied by the integrated molecular weight of the molecules in the file to determine the Matthews coefficient. This relation is being validated in this option. Be aware that the validation can get confused if both multiple copies of the molecule are present in the ATOM records and MTRIX records are present in the header of the PDB file.

Space group as read from CRYST card: P 21 21 21
Number of matrices in space group: 4
Highest polymer chain multiplicity in structure: 1
Highest polymer chain multiplicity according to SEQRES: 2
Such multiplicity differences are not by definition worrisome as it is very
well possible that this merely indicates that it is difficult to superpose
chains due to crystal induced differences
No explicit MTRIX NCS matrices found in the input file
Value of Z as found on the CRYST1 card: 4
Polymer chain multiplicity and SEQRES multiplicity disagree 1 2
Z and NCS seem to support the 3D multiplicity
There is strong evidence, though, for multiplicity and Z: 1 4

Warning: Matthews Coefficient (Vm) high

The Matthews coefficient [REF] is defined as the density of the protein structure in cubic Angstroms per Dalton. Normal values are between 1.5 (tightly packed, little room for solvent) and 4.0 (loosely packed, much space for solvent). Some very loosely packed structures can get values a bit higher than that.

Very high numbers are most often caused by giving the wrong value for Z on the CRYST1 card (or not giving this number at all), but can also result from large fractions missing out of the molecular weight (e.g. a lot of UNK residues, or DNA/RNA missing from virus structures).

Molecular weight of all polymer chains: 36430.613
Volume of the Unit Cell V= 421044.906
Space group multiplicity: 4
No NCS symmetry matrices (MTRIX records) found in PDB file
Matthews coefficient for observed atoms and Z high: Vm= 5.779
Vm by authors and this calculated Vm do not agree very well
Matthews coefficient read from REMARK 280 Vm= 2.570 SEQRES and ATOM multiplicities disagree. Error-reasoning thus is difficult.
(and the absence of MTRIX records doesn't help)
There is strong evidence, though, for multiplicity and Z: 1 4
which would result in the much more normal Vm= 2.889
and which also agrees with the number of NCS matrices (labeled `don't use')
that the user provided in the MTRIX records 1

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: Missing atoms

The atoms listed in the table below are missing from the entry. If many atoms are missing, the other checks can become less sensitive. Be aware that it often happens that groups at the termini of DNA or RNA are really missing, so that the absence of these atoms normally is neither an error nor the result of poor electron density. Some of the atoms listed here might also be listed by other checks, most noticeably by the options in the previous section that list missing atoms in several categories. The plausible atoms with zero occupancy are not listed here, as they already got assigned a non-zero occupancy, and thus are no longer 'missing'.

 107 GLU   (  88-)  A      CD
 107 GLU   (  88-)  A      OE1
 107 GLU   (  88-)  A      OE2
 110 GLU   (  91-)  A      OE1
 110 GLU   (  91-)  A      OE2
 152 GLU   ( 133-)  A      CD
 152 GLU   ( 133-)  A      OE1
 152 GLU   ( 133-)  A      OE2
 169 GLU   ( 150-)  A      CG
 169 GLU   ( 150-)  A      CD
 169 GLU   ( 150-)  A      OE1
 169 GLU   ( 150-)  A      OE2
 173 LYS   ( 154-)  A      CD
 173 LYS   ( 154-)  A      CE
 173 LYS   ( 154-)  A      NZ
 175 LYS   ( 156-)  A      CD
 175 LYS   ( 156-)  A      CE
 175 LYS   ( 156-)  A      NZ
 216 SER   ( 197-)  A      OG
 217 LYS   ( 198-)  A      CD
 217 LYS   ( 198-)  A      CE
 217 LYS   ( 198-)  A      NZ
 220 GLU   ( 201-)  A      OE1
 220 GLU   ( 201-)  A      OE2
 270 ARG   ( 251-)  A      NH1
 270 ARG   ( 251-)  A      NH2
 293 ARG   ( 274-)  A      CG
 293 ARG   ( 274-)  A      CD
 293 ARG   ( 274-)  A      NE
 293 ARG   ( 274-)  A      CZ
 293 ARG   ( 274-)  A      NH1
 293 ARG   ( 274-)  A      NH2

Warning: B-factors outside the range 0.0 - 100.0

In principle, B-factors can have a very wide range of values, but in practice, B-factors should not be zero while B-factors above 100.0 are a good indicator that the location of that atom is meaningless. Be aware that the cutoff at 100.0 is arbitrary. 'High' indicates that atoms with a B-factor > 100.0 were observed; 'Zero' indicates that atoms with a B-factor of zero were observed.

   1 DTHY  (   2-)  B    High
   2 DADE  (   3-)  B    High
   3 DGUA  (   4-)  B    High
   4 DADE  (   5-)  B    High
   5 DCYT  (   6-)  B    High
   9 DGUA  (  10-)  B    High
  10 DADE  (  11-)  B    High
  11 DTHY  (  14-)  C    High
  12 DCYT  (  15-)  C    High
  18 DCYT  (  21-)  C    High
  19 DTHY  (  22-)  C    High
  20 DADE  (  23-)  C    High

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:

Temperature cannot be read from the PDB file. This most likely means that the temperature is listed as NULL (meaning unknown) in the PDB file.

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: Arginine nomenclature problem

The arginine residues listed in the table below have their N-H-1 and N-H-2 swapped.

  76 ARG   (  57-)  A
 131 ARG   ( 112-)  A
 146 ARG   ( 127-)  A
 176 ARG   ( 157-)  A
 290 ARG   ( 271-)  A

Warning: Tyrosine convention problem

The tyrosine residues listed in the table below have their chi-2 not between -90.0 and 90.0

 100 TYR   (  81-)  A
 127 TYR   ( 108-)  A
 195 TYR   ( 176-)  A
 244 TYR   ( 225-)  A
 287 TYR   ( 268-)  A

Warning: Phenylalanine convention problem

The phenylalanine residues listed in the table below have their chi-2 not between -90.0 and 90.0.

  62 PHE   (  43-)  A
  80 PHE   (  61-)  A
  83 PHE   (  64-)  A
 133 PHE   ( 114-)  A
 162 PHE   ( 143-)  A
 254 PHE   ( 235-)  A

Warning: Aspartic acid convention problem

The aspartic acid residues listed in the table below have their chi-2 not between -90.0 and 90.0, or their proton on OD1 instead of OD2.

  44 ASP   (  25-)  A
  58 ASP   (  39-)  A
 121 ASP   ( 102-)  A
 129 ASP   ( 110-)  A
 184 ASP   ( 165-)  A

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.

  25 GLU   (   6-)  A
  75 GLU   (  56-)  A
  97 GLU   (  78-)  A
 142 GLU   ( 123-)  A
 156 GLU   ( 137-)  A
 198 GLU   ( 179-)  A
 218 GLU   ( 199-)  A
 224 GLU   ( 205-)  A
 232 GLU   ( 213-)  A
 250 GLU   ( 231-)  A

Geometric checks

Warning: Unusual bond angles

The bond angles listed in the table below were found to deviate more than 4 sigma from standard bond angles (both standard values and sigma for protein residues have been taken from Engh and Huber [REF], for DNA/RNA from Parkinson et al [REF]). In the table below for each strange angle the bond angle and the number of standard deviations it differs from the standard values is given. Please note that disulphide bridges are neglected. Atoms starting with "-" belong to the previous residue in the sequence.

   3 DGUA  (   4-)  B      N9   C8   N7  113.19    4.2
  14 DADE  (  17-)  C      C2'  C1'  N9  107.54   -4.2
  16 DGUA  (  19-)  C      N9   C8   N7  113.11    4.0

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.

  25 GLU   (   6-)  A
  44 ASP   (  25-)  A
  58 ASP   (  39-)  A
  75 GLU   (  56-)  A
  76 ARG   (  57-)  A
  97 GLU   (  78-)  A
 121 ASP   ( 102-)  A
 129 ASP   ( 110-)  A
 131 ARG   ( 112-)  A
 142 GLU   ( 123-)  A
 146 ARG   ( 127-)  A
 156 GLU   ( 137-)  A
 176 ARG   ( 157-)  A
 184 ASP   ( 165-)  A
 198 GLU   ( 179-)  A
 218 GLU   ( 199-)  A
 224 GLU   ( 205-)  A
 232 GLU   ( 213-)  A
 250 GLU   ( 231-)  A
 290 ARG   ( 271-)  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.

 144 ALA   ( 125-)  A    4.34

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.

 149 PRO   ( 130-)  A    -2.4
 174 THR   ( 155-)  A    -2.1
 188 VAL   ( 169-)  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.

  55 HIS   (  36-)  A  PRO omega poor
  85 LEU   (  66-)  A  Poor phi/psi
  95 ARG   (  76-)  A  Poor phi/psi
 112 HIS   (  93-)  A  Poor phi/psi
 132 LYS   ( 113-)  A  Poor phi/psi
 148 PRO   ( 129-)  A  PRO omega poor
 281 ALA   ( 262-)  A  Poor phi/psi
 chi-1/chi-2 correlation Z-score : -1.615

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 DGUA  (   4-)  B      0
   4 DADE  (   5-)  B      0
   5 DCYT  (   6-)  B      0
   6 DCYT  (   7-)  B      0
   7 DTHY  (   8-)  B      0
   8 DGUA  (   9-)  B      0
   9 DGUA  (  10-)  B      0
  10 DADE  (  11-)  B      0
  11 DTHY  (  14-)  C      0
  12 DCYT  (  15-)  C      0
  13 DCYT  (  16-)  C      0
  14 DADE  (  17-)  C      0
  15 8OG   (  18-)  C      0
  16 DGUA  (  19-)  C      0
  17 DTHY  (  20-)  C      0
  18 DCYT  (  21-)  C      0
  19 DTHY  (  22-)  C      0
  20 DADE  (  23-)  C      0
  21 PRO   (   2-)  A      0
  22 GLN   (   3-)  A      0
  38 VAL   (  19-)  A      0
  44 ASP   (  25-)  A      0
  48 PHE   (  29-)  A      0
  54 ARG   (  35-)  A      0
  55 HIS   (  36-)  A      0
And so on for a total of 116 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 : 1.255

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.

  97 GLU   (  78-)  A      CA  <->   99 ARG   (  80-)  A      NH1    0.32    2.78  INTRA BF
  93 HIS   (  74-)  A      CD2 <->   95 ARG   (  76-)  A      N      0.27    2.83  INTRA BL
   2 DADE  (   3-)  B      C2' <->    3 DGUA  (   4-)  B      C5'    0.26    2.94  INTRA BF
 191 PHE   ( 172-)  A      CZ  <->  230 ILE   ( 211-)  A      CG1    0.22    2.98  INTRA BL
  16 DGUA  (  19-)  C      C2' <->   17 DTHY  (  20-)  C      C5'    0.20    3.00  INTRA BF
 245 VAL   ( 226-)  A      N   <->  297 HOH   ( 331 )  A      O      0.18    2.52  INTRA BF
  30 ARG   (  11-)  A      NH1 <->   31 ARG   (  12-)  A      CG     0.18    2.92  INTRA BF
 154 GLY   ( 135-)  A      N   <->  185 CYS   ( 166-)  A      O      0.15    2.55  INTRA BF
   8 DGUA  (   9-)  B      O6  <->   13 DCYT  (  16-)  C      N4     0.15    2.55  INTRA BF
 209 ARG   ( 190-)  A      NH1 <->  218 GLU   ( 199-)  A      OE2    0.15    2.55  INTRA BF
 278 THR   ( 259-)  A      O   <->  285 THR   ( 266-)  A      N      0.14    2.56  INTRA BF
   8 DGUA  (   9-)  B      N1  <->   13 DCYT  (  16-)  C      N3     0.13    2.87  INTRA BF
  49 TRP   (  30-)  A      NE1 <->  295 HOH   (  37 )  B      O      0.12    2.58  INTRA BL
 143 GLU   ( 124-)  A      OE2 <->  146 ARG   ( 127-)  A      NH2    0.12    2.58  INTRA BF
  15 8OG   (  18-)  C      N7  <->  239 SER   ( 220-)  A      O      0.11    2.59  INTRA BL
 131 ARG   ( 112-)  A      NH1 <->  297 HOH   ( 314 )  A      O      0.11    2.59  INTRA BL
   6 DCYT  (   7-)  B      N3  <->    7 DTHY  (   8-)  B      C4     0.11    2.99  INTRA BF
   9 DGUA  (  10-)  B      N2  <->   12 DCYT  (  15-)  C      N3     0.10    2.90  INTRA BF
  54 ARG   (  35-)  A      CD  <->   57 ARG   (  38-)  A      NH1    0.10    3.00  INTRA BF
  27 GLU   (   8-)  A      OE2 <->   30 ARG   (  11-)  A      NH1    0.10    2.60  INTRA BF
  43 GLU   (  24-)  A      N   <->  118 CYS   (  99-)  A      O      0.10    2.60  INTRA BL
 198 GLU   ( 179-)  A      OE1 <->  259 TYR   ( 240-)  A      N      0.09    2.61  INTRA BL
 264 GLN   ( 245-)  A      NE2 <->  277 LYS   ( 258-)  A      CD     0.09    3.01  INTRA BF
  15 8OG   (  18-)  C      N2  <->  242 ARG   ( 223-)  A      NH1    0.09    2.91  INTRA BF
 137 HIS   ( 118-)  A      ND1 <->  297 HOH   ( 306 )  A      O      0.09    2.61  INTRA BL
And so on for a total of 64 lines.

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.

 242 ARG   ( 223-)  A      -7.04
  96 MET   (  77-)  A      -6.48
 106 LEU   (  87-)  A      -6.06
 257 HIS   ( 238-)  A      -5.68
 109 LEU   (  90-)  A      -5.38
 146 ARG   ( 127-)  A      -5.38
 158 LEU   ( 139-)  A      -5.18
 202 ARG   ( 183-)  A      -5.18
 133 PHE   ( 114-)  A      -5.06

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

Warning: Low packing Z-score for some residues

The residues listed in the table below have an unusual packing environment according to the 2nd generation packing check. The score listed in the table is a packing normality Z-score: positive means better than average, negative means worse than average. Only residues scoring less than -2.50 are listed here. These are the unusual residues in the structure, so it will be interesting to take a special look at them.

  94 LEU   (  75-)  A   -2.78
 131 ARG   ( 112-)  A   -2.73

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.

  93 HIS   (  74-)  A
 223 HIS   ( 204-)  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.

  21 PRO   (   2-)  A      N
  22 GLN   (   3-)  A      NE2
  30 ARG   (  11-)  A      NH1
  49 TRP   (  30-)  A      N
  51 ASN   (  32-)  A      N
  92 SER   (  73-)  A      OG
  95 ARG   (  76-)  A      NE
  99 ARG   (  80-)  A      NH2
 109 LEU   (  90-)  A      N
 110 GLU   (  91-)  A      N
 131 ARG   ( 112-)  A      N
 145 ASP   ( 126-)  A      N
 152 GLU   ( 133-)  A      N
 158 LEU   ( 139-)  A      N
 163 SER   ( 144-)  A      N
 173 LYS   ( 154-)  A      N
 212 ALA   ( 193-)  A      N
 241 VAL   ( 222-)  A      N
 242 ARG   ( 223-)  A      N
 243 THR   ( 224-)  A      N
 244 TYR   ( 225-)  A      N
 245 VAL   ( 226-)  A      N
 262 GLY   ( 243-)  A      N
 283 ARG   ( 264-)  A      NH2

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.

  25 GLU   (   6-)  A   H-bonding suggests Gln

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 :  -0.583
  2nd generation packing quality :  -0.481
  Ramachandran plot appearance   :  -1.837
  chi-1/chi-2 rotamer normality  :  -1.615
  Backbone conformation          :   0.499

RMS Z-scores, should be close to 1.0:
  Bond lengths                   :   0.313 (tight)
  Bond angles                    :   0.653 (tight)
  Omega angle restraints         :   0.228 (tight)
  Side chain planarity           :   0.205 (tight)
  Improper dihedral distribution :   0.608
  B-factor distribution          :   0.443
  Inside/Outside distribution    :   1.024

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 : 2.35


Structure Z-scores, positive is better than average:

  1st generation packing quality :   0.3
  2nd generation packing quality :   0.6
  Ramachandran plot appearance   :  -0.2
  chi-1/chi-2 rotamer normality  :  -0.5
  Backbone conformation          :   0.2

RMS Z-scores, should be close to 1.0:
  Bond lengths                   :   0.313 (tight)
  Bond angles                    :   0.653 (tight)
  Omega angle restraints         :   0.228 (tight)
  Side chain planarity           :   0.205 (tight)
  Improper dihedral distribution :   0.608
  B-factor distribution          :   0.443
  Inside/Outside distribution    :   1.024
==============

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.