WHAT IF Check report

This file was created 2011-12-16 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 pdb1hx0.ent

Checks that need to be done early-on in validation

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: 56715.621
Volume of the Unit Cell V= 921683.500
Space group multiplicity: 4
No NCS symmetry matrices (MTRIX records) found in PDB file
Matthews coefficient for observed atoms and Z a bit high: Vm= 4.063
Vm by authors and this calculated Vm agree well
Matthews coefficient read from REMARK 280 Vm= 4.150

Warning: Ligands for which a topology was generated automatically

The topology for the ligands in the table below were determined automatically. WHAT IF uses a local copy of Daan van Aalten's Dundee PRODRG server to automatically generate topology information for ligands. For this PDB file that seems to have gone fine, but be aware that automatic topology generation is a complicated task. So, if you get messages that you fail to understand or that you believe are wrong, and one of these ligands is involved, then check the ligand topology first.

 500 AC1   (1990-)  A  -
 519 MAL   (1994-)  A  -
 520 BGC   (2993-)  A  -
 521 AC1   (1992-)  A  -

Administrative problems that can generate validation failures

Warning: Alternate atom problems encountered

The residues listed in the table below have alternate atoms. One of two problems might have been encountered: 1) The software did not properly deal with the alternate atoms; 2) The alternate atom indicators are too wrong to sort out.

Alternate atom indicators in PDB files are known to often be erroneous. It has been observed that alternate atom indicators are missing, or that there are too many of them. It is common to see that the distance between two atoms that should be covalently bound is far too big, but the distance between the alternate A of one of them and alternate B of the other is proper for a covalent bond. We have discovered many, many ways in which alternate atoms can be abused. The software tries to deal with most cases, but we know for sure that it cannot deal with all cases. If an alternate atom indicator problem is not properly solved, subsequent checks will list errors that are based on wrong coordinate combinations. So, any problem listed in this table should be solved before error messages further down in this report can be trusted.

  55 SER   (  55-)  A  -
 124 ARG   ( 124-)  A  -
 338 VAL   ( 338-)  A  -
 444 LEU   ( 444-)  A  -
 471 SER   ( 471-)  A  -

Warning: Alternate atom problems quasi solved

The residues listed in the table below have alternate atoms that WHAT IF decided to correct (e.g. take alternate atom B instead of A for one or more of the atoms). Residues for which the use of alternate atoms is non-standard, but WHAT IF left it that way because he liked the non-standard situation better than other solutions, are listed too in this table.

In case any of these residues shows up as poor or bad in checks further down this report, please check the consistency of the alternate atoms in this residue first, correct it yourself if needed, and run the validation again.

  55 SER   (  55-)  A  -
 124 ARG   ( 124-)  A  -
 338 VAL   ( 338-)  A  -
 444 LEU   ( 444-)  A  -
 471 SER   ( 471-)  A  -
Delete overlapping entity  520 BGC  (2993-) A  -

Warning: Overlapping residues or molecules

This molecule contains residues or molecules that overlap too much while not being (administrated as) alternate atom/residue pairs. The residues or molecules listed in the table below have been removed before the validation continued.

Overlapping residues or molecules (for short entities) are occasionally observed in the PDB. Often these are cases like, for example, two sugars that bind equally well in the same active site, are both seen overlapping in the density, and are both entered in the PDB file as separate entities. This can cause some false positive error messsages further down the validation path, and therefore the second of the overlapping entities has been deleted before the validation continued. If you want to validate both situations, make it two PDB files, one for each sugar. And fudge reality a bit by making the occupancy of the sugar atoms 1.0 in both cases, because many validation options are not executed on atoms with low occupancy. If you go for this two-file option, please make sure that any side chains that have alternate locations depending on the sugar bound are selected in each of the two cases in agreement with the sugar that you keep for validation in that particular file.

 520 BGC   (2993-)  A  -

Warning: Groups attached to potentially hydrogenbonding atoms

Residues were observed with groups attached to (or very near to) atoms that potentially can form hydrogen bonds. WHAT IF is not very good at dealing with such exceptional cases (Mainly because it's author is not...). So be warned that the hydrogenbonding-related analyses of these residues might be in error.

For example, an aspartic acid can be protonated on one of its delta oxygens. This is possible because the one delta oxygen 'helps' the other one holding that proton. However, if a delta oxygen has a group bound to it, then it can no longer 'help' the other delta oxygen bind the proton. However, both delta oxygens, in principle, can still be hydrogen bond acceptors. Such problems can occur in the amino acids Asp, Glu, and His. I have opted, for now to simply allow no hydrogen bonds at all for any atom in any side chain that somewhere has a 'funny' group attached to it. I know this is wrong, but there are only 12 hours in a day.

 497 GLC   (1991-)  A  -   O4  bound to  499 AC1   (1990-)  A  -   C1

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

Warning: Unexpected atoms encountered

While reading the PDB file, at least one atom was encountered that was not expected in the residue. This might be caused by a naming convention problem. It can also mean that a residue was found protonated that normally is not (e.g. aspartic acid). The unexpected atoms have been discarded; in case protons were deleted that actually might be needed, they will later be put back by the hydrogen bond validation software. This normally is not a warning you should worry too much about.

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.

 460 ASN   ( 460-)  A    High

Warning: Occupancies atoms do not add up to 1.0.

In principle, the occupancy of all alternates of one atom should add up till 1.0. A valid exception is the missing atom (i.e. an atom not seen in the electron density) that is allowed to have a 0.0 occupancy. Sometimes this even happens when there are no alternate atoms given...

Atoms want to move. That is the direct result of the second law of thermodynamics, in a somewhat weird way of thinking. Any way, many atoms seem to have more than one position where they like to sit, and they jump between them. The population difference between those sites (which is related to their energy differences) is seen in the occupancy factors. As also for atoms it is 'to be or not to be', these occupancies should add up to 1.0. Obviously, it is possible that they add up to a number less than 1.0, in cases where there are yet more, but undetected' rotamers/positions in play, but also in those cases a warning is in place as the information shown in the PDB file is less certain than it could have been. The residues listed below contain atoms that have an occupancy greater than zero, but all their alternates do not add up to one.

WARNING. Presently WHAT CHECK only deals with a maximum of two alternate positions. A small number of atoms in the PDB has three alternates. In those cases the warning given here should obviously be neglected! In a next release we will try to fix this.

   7 GLN   (   7-)  A    0.70

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) :100.000

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.

  20 ARG   (  20-)  A
  30 ARG   (  30-)  A
  56 ARG   (  56-)  A
  61 ARG   (  61-)  A
  72 ARG   (  72-)  A
  80 ARG   (  80-)  A
  85 ARG   (  85-)  A
  92 ARG   (  92-)  A
 176 ARG   ( 176-)  A
 227 ARG   ( 227-)  A
 252 ARG   ( 252-)  A
 267 ARG   ( 267-)  A
 291 ARG   ( 291-)  A
 319 ARG   ( 319-)  A
 337 ARG   ( 337-)  A
 343 ARG   ( 343-)  A
 387 ARG   ( 387-)  A
 389 ARG   ( 389-)  A
 392 ARG   ( 392-)  A
 398 ARG   ( 398-)  A
 421 ARG   ( 421-)  A
 424 ARG   ( 424-)  A

Warning: Tyrosine convention problem

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

  31 TYR   (  31-)  A
  62 TYR   (  62-)  A
 151 TYR   ( 151-)  A
 155 TYR   ( 155-)  A
 182 TYR   ( 182-)  A
 247 TYR   ( 247-)  A
 276 TYR   ( 276-)  A
 449 TYR   ( 449-)  A

Warning: Phenylalanine convention problem

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

  17 PHE   (  17-)  A
 126 PHE   ( 126-)  A
 194 PHE   ( 194-)  A
 222 PHE   ( 222-)  A
 229 PHE   ( 229-)  A
 231 PHE   ( 231-)  A
 286 PHE   ( 286-)  A
 295 PHE   ( 295-)  A
 315 PHE   ( 315-)  A
 327 PHE   ( 327-)  A
 397 PHE   ( 397-)  A
 406 PHE   ( 406-)  A
 419 PHE   ( 419-)  A
 477 PHE   ( 477-)  A
 487 PHE   ( 487-)  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.

  23 ASP   (  23-)  A
  96 ASP   (  96-)  A
 135 ASP   ( 135-)  A
 138 ASP   ( 138-)  A
 153 ASP   ( 153-)  A
 159 ASP   ( 159-)  A
 181 ASP   ( 181-)  A
 188 ASP   ( 188-)  A
 197 ASP   ( 197-)  A
 206 ASP   ( 206-)  A
 290 ASP   ( 290-)  A
 300 ASP   ( 300-)  A
 317 ASP   ( 317-)  A
 353 ASP   ( 353-)  A
 375 ASP   ( 375-)  A
 402 ASP   ( 402-)  A
 432 ASP   ( 432-)  A
 433 ASP   ( 433-)  A
 451 ASP   ( 451-)  A
 456 ASP   ( 456-)  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.

  47 GLU   (  47-)  A
  60 GLU   (  60-)  A
  76 GLU   (  76-)  A
 125 GLU   ( 125-)  A
 149 GLU   ( 149-)  A
 233 GLU   ( 233-)  A
 240 GLU   ( 240-)  A
 246 GLU   ( 246-)  A
 272 GLU   ( 272-)  A
 352 GLU   ( 352-)  A
 369 GLU   ( 369-)  A
 385 GLU   ( 385-)  A
 390 GLU   ( 390-)  A
 493 GLU   ( 493-)  A

Geometric checks

Warning: Unusual bond lengths

The bond lengths listed in the table below were found to deviate more than 4 sigma from standard bond lengths (both standard values and sigmas for amino acid residues have been taken from Engh and Huber [REF], for DNA they were taken from Parkinson et al [REF]). In the table below for each unusual bond the bond length and the number of standard deviations it differs from the normal value is given.

Atom names starting with "-" belong to the previous residue in the chain. If the second atom name is "-SG*", the disulphide bridge has a deviating length.

 444 LEU   ( 444-)  A      CG   CD1   1.12  -12.1
 444 LEU   ( 444-)  A      CG   CD2   1.76    7.3

Warning: Low bond length variability

Bond lengths were found to deviate less than normal from the mean Engh and Huber [REF] and/or Parkinson et al [REF] standard bond lengths. The RMS Z-score given below is expected to be near 1.0 for a normally restrained data set. The fact that it is lower than 0.667 in this structure might indicate that too-strong restraints have been used in the refinement. This can only be a problem for high resolution X-ray structures.

RMS Z-score for bond lengths: 0.602
RMS-deviation in bond distances: 0.013

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.

  10 ARG   (  10-)  A      CD   NE   CZ  129.06    4.1
  15 HIS   (  15-)  A      CB   CG   ND1 131.89    6.9
  15 HIS   (  15-)  A      CG   ND1  CE1 110.20    4.6
  15 HIS   (  15-)  A      ND1  CE1  NE2 105.94   -4.4
  15 HIS   (  15-)  A      CB   CG   CD2 122.42   -5.1
  20 ARG   (  20-)  A      CG   CD   NE  120.48    5.9
  20 ARG   (  20-)  A      CD   NE   CZ  134.64    7.2
  41 GLN   (  41-)  A      NE2  CD   OE1 127.12    4.5
  46 ASN   (  46-)  A      CA   CB   CG  107.94   -4.7
  59 TRP   (  59-)  A      CA   CB   CG  121.82    4.3
  62 TYR   (  62-)  A      CA   CB   CG  105.71   -4.2
  70 CYS   (  70-)  A      N    CA   CB  103.42   -4.2
  77 ASN   (  77-)  A      CA   CB   CG  116.67    4.1
  77 ASN   (  77-)  A      CB   CG   ND2 123.04    4.4
  77 ASN   (  77-)  A      ND2  CG   OD1 118.00   -4.6
  96 ASP   (  96-)  A      CA   CB   CG  117.06    4.5
 100 ASN   ( 100-)  A      CB   CG   ND2 122.60    4.1
 100 ASN   ( 100-)  A      ND2  CG   OD1 114.88   -7.7
 101 HIS   ( 101-)  A      CB   CG   ND1 128.08    4.3
 101 HIS   ( 101-)  A      CG   ND1  CE1 122.21   16.6
 101 HIS   ( 101-)  A      ND1  CE1  NE2  98.58  -10.1
 101 HIS   ( 101-)  A      CD2  CG   ND1  98.13   -8.0
 124 ARG   ( 124-)  A      CD   NE   CZ  147.88   14.5
 130 PRO   ( 130-)  A     -CA  -C    N   125.49    5.7
 131 TYR   ( 131-)  A      CA   CB   CG  121.42    4.1
And so on for a total of 75 lines.

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.

  20 ARG   (  20-)  A
  23 ASP   (  23-)  A
  30 ARG   (  30-)  A
  47 GLU   (  47-)  A
  56 ARG   (  56-)  A
  60 GLU   (  60-)  A
  61 ARG   (  61-)  A
  72 ARG   (  72-)  A
  76 GLU   (  76-)  A
  80 ARG   (  80-)  A
  85 ARG   (  85-)  A
  92 ARG   (  92-)  A
  96 ASP   (  96-)  A
 125 GLU   ( 125-)  A
 135 ASP   ( 135-)  A
 138 ASP   ( 138-)  A
 149 GLU   ( 149-)  A
 153 ASP   ( 153-)  A
 159 ASP   ( 159-)  A
 176 ARG   ( 176-)  A
 181 ASP   ( 181-)  A
 188 ASP   ( 188-)  A
 197 ASP   ( 197-)  A
 206 ASP   ( 206-)  A
 227 ARG   ( 227-)  A
And so on for a total of 56 lines.

Warning: Chirality deviations detected

The atoms listed in the table below have an improper dihedral value that is deviating from expected values. As the improper dihedral values are all getting very close to ideal values in recent X-ray structures, and as we actually do not know how big the spread around these values should be, this check only warns for 6 sigma deviations.

Improper dihedrals are a measure of the chirality/planarity of the structure at a specific atom. Values around -35 or +35 are expected for chiral atoms, and values around 0 for planar atoms. Planar side chains are left out of the calculations, these are better handled by the planarity checks.

Three numbers are given for each atom in the table. The first is the Z-score for the improper dihedral. The second number is the measured improper dihedral. The third number is the expected value for this atom type. A final column contains an extra warning if the chirality for an atom is opposite to the expected value.

Please also see the previous table that lists a series of administrative chirality problems that were corrected automatically upon reading-in the PDB file.

 444 LEU   ( 444-)  A    B CG    15.0    -6.53   -33.01
The average deviation= 1.101

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.

  45 PRO   (  45-)  A    -2.7
 486 PRO   ( 486-)  A    -2.2
 163 VAL   ( 163-)  A    -2.2
 459 GLY   ( 459-)  A    -2.1
 422 GLY   ( 422-)  A    -2.0
  56 ARG   (  56-)  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.

   5 GLN   (   5-)  A  Poor phi/psi
  10 ARG   (  10-)  A  omega poor
  18 GLU   (  18-)  A  Poor phi/psi
  53 ASN   (  53-)  A  PRO omega poor
 102 MET   ( 102-)  A  Poor phi/psi
 124 ARG   ( 124-)  A  Poor phi/psi
 129 VAL   ( 129-)  A  PRO omega poor
 194 PHE   ( 194-)  A  omega poor
 198 ALA   ( 198-)  A  Poor phi/psi
 215 HIS   ( 215-)  A  omega poor
 221 TRP   ( 221-)  A  Poor phi/psi
 268 LYS   ( 268-)  A  Poor phi/psi
 270 SER   ( 270-)  A  Poor phi/psi
 292 ALA   ( 292-)  A  omega poor
 317 ASP   ( 317-)  A  omega poor
 340 SER   ( 340-)  A  omega poor
 341 SER   ( 341-)  A  omega poor
 364 ASN   ( 364-)  A  Poor phi/psi
 376 THR   ( 376-)  A  Poor phi/psi
 380 ASN   ( 380-)  A  Poor phi/psi
 381 ASP   ( 381-)  A  Poor phi/psi, omega poor
 414 SER   ( 414-)  A  Poor phi/psi
 422 GLY   ( 422-)  A  Poor phi/psi
 435 GLN   ( 435-)  A  omega poor
 456 ASP   ( 456-)  A  omega poor
 486 PRO   ( 486-)  A  Poor phi/psi
 chi-1/chi-2 correlation Z-score : -0.584

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!

   5 GLN   (   5-)  A      0
   8 SER   (   8-)  A      0
  12 SER   (  12-)  A      0
  17 PHE   (  17-)  A      0
  18 GLU   (  18-)  A      0
  19 TRP   (  19-)  A      0
  30 ARG   (  30-)  A      0
  31 TYR   (  31-)  A      0
  32 LEU   (  32-)  A      0
  45 PRO   (  45-)  A      0
  48 ASN   (  48-)  A      0
  53 ASN   (  53-)  A      0
  54 PRO   (  54-)  A      0
  55 SER   (  55-)  A      0
  56 ARG   (  56-)  A      0
  57 PRO   (  57-)  A      0
  59 TRP   (  59-)  A      0
  62 TYR   (  62-)  A      0
  63 GLN   (  63-)  A      0
  64 PRO   (  64-)  A      0
  67 TYR   (  67-)  A      0
  69 LEU   (  69-)  A      0
  70 CYS   (  70-)  A      0
  73 SER   (  73-)  A      0
  75 ASN   (  75-)  A      0
And so on for a total of 216 lines.

Warning: Unusual PRO puckering amplitudes

The proline residues listed in the table below have a puckering amplitude that is outside of normal ranges. Puckering parameters were calculated by the method of Cremer and Pople [REF]. Normal PRO rings have a puckering amplitude Q between 0.20 and 0.45 Angstrom. If Q is lower than 0.20 Angstrom for a PRO residue, this could indicate disorder between the two different normal ring forms (with C-gamma below and above the ring, respectively). If Q is higher than 0.45 Angstrom something could have gone wrong during the refinement. Be aware that this is a warning with a low confidence level. See: Who checks the checkers? Four validation tools applied to eight atomic resolution structures [REF]

 228 PRO   ( 228-)  A    0.11 LOW

Warning: Unusual PRO puckering phases

The proline residues listed in the table below have a puckering phase that is not expected to occur in protein structures. Puckering parameters were calculated by the method of Cremer and Pople [REF]. Normal PRO rings approximately show a so-called envelope conformation with the C-gamma atom above the plane of the ring (phi=+72 degrees), or a half-chair conformation with C-gamma below and C-beta above the plane of the ring (phi=-90 degrees). If phi deviates strongly from these values, this is indicative of a very strange conformation for a PRO residue, and definitely requires a manual check of the data. Be aware that this is a warning with a low confidence level. See: Who checks the checkers? Four validation tools applied to eight atomic resolution structures [REF].

 130 PRO   ( 130-)  A   -63.2 envelop C-beta (-72 degrees)

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.

 515 EDO   (5013-)  A      O2  <->  517 MAL   (1994-)  A      C1'    1.00    1.40  INTRA B3
 515 EDO   (5013-)  A      C2  <->  517 MAL   (1994-)  A      C1'    0.80    2.40  INTRA
 240 GLU   ( 240-)  A    A OE1 <->  518 HOH   (6946 )  A      O      0.44    1.96  INTRA
 518 HOH   (6179 )  A    A O   <->  518 HOH   (6179 )  A    B O      0.23    1.97  INTRA
  77 ASN   (  77-)  A    A ND2 <->  518 HOH   (6262 )  A      O      0.22    2.48  INTRA
 346 ARG   ( 346-)  A    A NH2 <->  518 HOH   (6630 )  A      O      0.22    2.48  INTRA
 149 GLU   ( 149-)  A      N   <->  156 GLN   ( 156-)  A    A OE1    0.21    2.49  INTRA BL
 268 LYS   ( 268-)  A      NZ  <->  518 HOH   (6680 )  A      O      0.21    2.49  INTRA BF
 240 GLU   ( 240-)  A    A OE2 <->  518 HOH   (6721 )  A      O      0.20    2.20  INTRA BF
 273 LYS   ( 273-)  A      NZ  <->  518 HOH   (6144 )  A      O      0.20    2.50  INTRA BF
 200 LYS   ( 200-)  A      NZ  <->  518 HOH   (6946 )  A      O      0.20    2.50  INTRA
 278 LYS   ( 278-)  A      NZ  <->  518 HOH   (6615 )  A      O      0.19    2.51  INTRA BF
 346 ARG   ( 346-)  A    A NE  <->  518 HOH   (6630 )  A      O      0.19    2.51  INTRA
 373 ASN   ( 373-)  A      ND2 <->  518 HOH   (6942 )  A      O      0.17    2.53  INTRA
 518 HOH   (6167 )  A    A O   <->  518 HOH   (6903 )  A      O      0.14    2.06  INTRA
 503  CL   ( 502-)  A     CL   <->  518 HOH   (6309 )  A      O      0.12    2.68  INTRA
 124 ARG   ( 124-)  A    A NH2 <->  518 HOH   (6160 )  A      O      0.12    2.58  INTRA
 517 MAL   (1994-)  A      O2' <->  518 HOH   (6684 )  A      O      0.11    2.29  INTRA
 518 HOH   (6451 )  A    A O   <->  518 HOH   (6451 )  A    B O      0.11    2.09  INTRA
 138 ASP   ( 138-)  A    A OD1 <->  518 HOH   (6415 )  A      O      0.11    2.29  INTRA BF
 227 ARG   ( 227-)  A    A NH2 <->  514 EDO   (5010-)  A      C2     0.10    3.00  INTRA
 123 ASN   ( 123-)  A      OD1 <->  518 HOH   (6454 )  A      O      0.10    2.30  INTRA BF
 141 CYS   ( 141-)  A      O   <->  518 HOH   (6691 )  A      O      0.10    2.30  INTRA
 150 SER   ( 150-)  A      N   <->  156 GLN   ( 156-)  A    A OE1    0.09    2.61  INTRA
 457 LYS   ( 457-)  A      NZ  <->  518 HOH   (6980 )  A      O      0.08    2.62  INTRA BF
 518 HOH   (6215 )  A    A O   <->  518 HOH   (6975 )  A      O      0.07    2.13  INTRA BF
  78 GLU   (  78-)  A      OE2 <->  518 HOH   (6713 )  A      O      0.06    2.34  INTRA BF
 137 ASN   ( 137-)  A    A ND2 <->  518 HOH   (6273 )  A      O      0.06    2.64  INTRA
 507 EDO   (5002-)  A    A C2  <->  518 HOH   (6557 )  A    B O      0.06    2.74  INTRA
 240 GLU   ( 240-)  A    A CB  <->  518 HOH   (6946 )  A      O      0.05    2.75  INTRA
 138 ASP   ( 138-)  A    A O   <->  518 HOH   (6691 )  A      O      0.05    2.35  INTRA
 200 LYS   ( 200-)  A      CE  <->  518 HOH   (6946 )  A      O      0.04    2.76  INTRA
 240 GLU   ( 240-)  A    A CD  <->  518 HOH   (6721 )  A      O      0.03    2.77  INTRA BF
 185 LYS   ( 185-)  A      NZ  <->  518 HOH   (6808 )  A      O      0.03    2.67  INTRA BF
 373 ASN   ( 373-)  A      ND2 <->  518 HOH   (6508 )  A      O      0.03    2.67  INTRA
  15 HIS   (  15-)  A      CD2 <->  518 HOH   (6195 )  A      O      0.03    2.77  INTRA BL
  15 HIS   (  15-)  A      CE1 <->  518 HOH   (6022 )  A      O      0.02    2.78  INTRA BL
 236 ASP   ( 236-)  A      OD2 <->  518 HOH   (6541 )  A      O      0.01    2.39  INTRA
 140 LYS   ( 140-)  A    A CE  <->  518 HOH   (6302 )  A      O      0.01    2.79  INTRA
  35 LYS   (  35-)  A      NZ  <->  518 HOH   (6450 )  A      O      0.01    2.69  INTRA BF
  27 GLU   (  27-)  A      OE2 <->  386 HIS   ( 386-)  A      NE2    0.01    2.69  INTRA BL
 138 ASP   ( 138-)  A    A OD2 <->  518 HOH   (6272 )  A      O      0.01    2.39  INTRA

Packing, accessibility and threading

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.

  72 ARG   (  72-)  A      -7.01
 343 ARG   ( 343-)  A      -5.61
   2 TYR   (   2-)  A      -5.60
 118 TYR   ( 118-)  A      -5.56
 284 TRP   ( 284-)  A      -5.42
 279 ASN   ( 279-)  A      -5.36
  88 ASN   (  88-)  A      -5.28
  30 ARG   (  30-)  A      -5.28
 302 GLN   ( 302-)  A      -5.24
  53 ASN   (  53-)  A      -5.24
 123 ASN   ( 123-)  A      -5.22
 303 ARG   ( 303-)  A      -5.22
   7 GLN   (   7-)  A      -5.13

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.

 238 GLY   ( 238-)  A   -2.95
 276 TYR   ( 276-)  A   -2.63
  17 PHE   (  17-)  A   -2.51

Water, ion, and hydrogenbond related checks

Warning: Water molecules need moving

The water molecules listed in the table below were found to be significantly closer to a symmetry related non-water molecule than to the ones given in the coordinate file. For optimal viewing convenience revised coordinates for these water molecules should be given.

The number in brackets is the identifier of the water molecule in the input file. Suggested coordinates are also given in the table. Please note that alternative conformations for protein residues are not taken into account for this calculation. If you are using WHAT IF / WHAT-CHECK interactively, then the moved waters can be found in PDB format in the file: MOVEDH2O.pdb.

 518 HOH   (6180 )  A      O     48.30   42.46   56.84
 518 HOH   (6188 )  A    A O     12.88   10.49   57.27
 518 HOH   (6188 )  A    B O     11.83   11.82   57.42
 518 HOH   (6189 )  A      O     46.67   45.52   55.45
 518 HOH   (6245 )  A      O     48.01   47.13   52.46
 518 HOH   (6331 )  A      O     54.44   48.89   42.09
 518 HOH   (6353 )  A      O     45.90   54.87   18.98
 518 HOH   (6380 )  A      O     45.59   25.69   55.44
 518 HOH   (6410 )  A      O     49.20   30.82   50.03
 518 HOH   (6411 )  A      O     51.67   31.21   48.67
 518 HOH   (6414 )  A      O     52.07   30.05   46.13
 518 HOH   (6497 )  A      O     37.96   -8.26   45.50
 518 HOH   (6519 )  A      O     56.10   16.27   58.08
 518 HOH   (6662 )  A    A O     56.85   30.17   48.48
 518 HOH   (6702 )  A      O     15.95   41.07   44.70
 518 HOH   (6738 )  A      O     46.55   58.70   30.51
 518 HOH   (6741 )  A      O     55.34   48.04   44.34
 518 HOH   (6869 )  A    B O     25.11   10.28   71.45
 518 HOH   (6922 )  A      O      8.49   31.58   55.01
 518 HOH   (6939 )  A      O     38.51   38.72   61.29
 518 HOH   (6989 )  A      O     37.98    5.42   23.95
 518 HOH   (6998 )  A      O     48.04   53.99   10.93

Error: Water molecules without hydrogen bonds

The water molecules listed in the table below do not form any hydrogen bonds, neither with the protein or DNA/RNA, nor with other water molecules. This is a strong indication of a refinement problem. The last number on each line is the identifier of the water molecule in the input file.

 518 HOH   (6416 )  A      O
 518 HOH   (6593 )  A      O
 518 HOH   (6608 )  A      O
 518 HOH   (6650 )  A      O
 518 HOH   (6767 )  A      O
 518 HOH   (6860 )  A      O
 518 HOH   (6936 )  A      O
 518 HOH   (6948 )  A      O
Marked this atom as acceptor  500  CL  ( 498-) A     CL
Marked this atom as acceptor  501  CL  ( 499-) A     CL
Marked this atom as acceptor  502  CL  ( 501-) A     CL
Marked this atom as acceptor  503  CL  ( 502-) A     CL
Strange metal coordination for HIS 201

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.

 101 HIS   ( 101-)  A
 363 ASN   ( 363-)  A
 373 ASN   ( 373-)  A
 408 ASN   ( 408-)  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.

  59 TRP   (  59-)  A      N
  87 ASN   (  87-)  A      ND2
 100 ASN   ( 100-)  A      ND2
 101 HIS   ( 101-)  A      N
 106 GLY   ( 106-)  A      N
 193 GLY   ( 193-)  A      N
 251 GLY   ( 251-)  A      N
 273 LYS   ( 273-)  A      N
 281 GLY   ( 281-)  A      N
 295 PHE   ( 295-)  A      N
 300 ASP   ( 300-)  A      N
 316 TRP   ( 316-)  A      NE1
 337 ARG   ( 337-)  A      NH2
 344 TRP   ( 344-)  A      N
 357 TRP   ( 357-)  A      N
 370 VAL   ( 370-)  A      N
 371 THR   ( 371-)  A      N
 434 TRP   ( 434-)  A      N
Only metal coordination for  100 ASN  ( 100-) A      OD1
Only metal coordination for  167 ASP  ( 167-) A      OD2

Warning: Buried unsatisfied hydrogen bond acceptors

The buried side-chain hydrogen bond acceptors listed in the table below are not involved in a hydrogen bond in the optimized hydrogen bond network.

Side-chain hydrogen bond acceptors buried inside the protein normally form hydrogen bonds within the protein. If there are any not hydrogen bonded in the optimized hydrogen bond network they will be listed here.

Waters are not listed by this option.

  15 HIS   (  15-)  A      NE2

Warning: Unusual ion packing

We implemented the ion valence determination method of Brown and Wu [REF] similar to Nayal and Di Cera [REF]. See also 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 has great potential, but the method has not been validated. Part of our implementation (comparing 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 validation method is untested. See: swift.cmbi.ru.nl/teach/theory/ for a detailed explanation.

The output gives the ion, the valency score for the ion itself, the valency score for the suggested alternative ion, and a series of possible comments *1 indicates that the suggested alternate atom type has been observed in the PDB file at another location in space. *2 indicates that WHAT IF thinks to have found this ion type in the crystallisation conditions as described in the REMARK 280 cards of the PDB file. *S Indicates that this ions is located at a special position (i.e. at a symmetry axis). N4 stands for NH4+.

 504  CA   ( 500-)  A     0.78   1.02 Scores about as good as NA

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.

 518 HOH   (6024 )  A      O  1.09  K  4
 518 HOH   (6060 )  A      O  0.92  K  4
 518 HOH   (6068 )  A      O  0.95  K  4
 518 HOH   (6075 )  A    B O  1.10 CA  5 *1 and *2 (or NA)
 518 HOH   (6132 )  A      O  0.99  K  4
 518 HOH   (6208 )  A      O  1.01  K  5
 518 HOH   (6259 )  A      O  1.13  K  4
 518 HOH   (6313 )  A      O  1.07  K  5 Ion-B
 518 HOH   (6340 )  A      O  0.97  K  4 Ion-B
 518 HOH   (6733 )  A      O  0.96  K  4 ION-B H2O-B

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.

 181 ASP   ( 181-)  A   H-bonding suggests Asn
 352 GLU   ( 352-)  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 :  -0.752
  2nd generation packing quality :  -1.884
  Ramachandran plot appearance   :  -0.718
  chi-1/chi-2 rotamer normality  :  -0.584
  Backbone conformation          :  -0.946

RMS Z-scores, should be close to 1.0:
  Bond lengths                   :   0.602 (tight)
  Bond angles                    :   1.258
  Omega angle restraints         :   1.138
  Side chain planarity           :   0.802
  Improper dihedral distribution :   0.984
  B-factor distribution          :   0.810
  Inside/Outside distribution    :   0.996

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 : 1.38


Structure Z-scores, positive is better than average:

  1st generation packing quality :  -0.4
  2nd generation packing quality :  -1.7
  Ramachandran plot appearance   :  -1.2
  chi-1/chi-2 rotamer normality  :  -1.2
  Backbone conformation          :  -1.3

RMS Z-scores, should be close to 1.0:
  Bond lengths                   :   0.602 (tight)
  Bond angles                    :   1.258
  Omega angle restraints         :   1.138
  Side chain planarity           :   0.802
  Improper dihedral distribution :   0.984
  B-factor distribution          :   0.810
  Inside/Outside distribution    :   0.996
==============

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.