WHAT IF Check report

This file was created 2011-12-15 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 pdb1f8b.ent

Checks that need to be done early-on in validation

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.

 395 MAN   ( 471-)  A  -
 396 MAN   ( 472-)  A  -
 397 MAN   ( 473-)  A  -
 398 MAN   ( 474-)  A  -
 401 DAN   (   0-)  A  -
 402 MAN   ( 475-)  A  -

Administrative problems that can generate validation failures

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.

 389 NAG   ( 469-)  A  -   O4  bound to  390 NAG   ( 470-)  A  -   C1
 390 NAG   ( 470-)  A  -   O4  bound to  395 MAN   ( 471-)  A  -   C1

Warning: Plausible side chain atoms detected with zero occupancy

Plausible side chain atoms were detected with (near) zero occupancy

When crystallographers do not see an atom they either leave it out completely, or give it an occupancy of zero or a very high B-factor. WHAT IF neglects these atoms. In this case some atoms were found with zero occupancy, but with coordinates that place them at a plausible position. Although WHAT IF knows how to deal with missing side chain atoms, validation will go more reliable if all atoms are presnt. So, please consider manually setting the occupancy of the listed atoms at 1.0.

  46 ASP   ( 127-)  A  -   OD1
 181 LYS   ( 261-)  A  -   CE
 181 LYS   ( 261-)  A  -   NZ
 336 GLU   ( 416-)  A  -   OE1
 336 GLU   ( 416-)  A  -   OE2
 383 LYS   ( 463-)  A  -   NZ

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'.

 392 NAG   (1087-)  A      O7
 392 NAG   (1087-)  A      C8

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) :113.000

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.

   1 ARG   (  82-)  A
  26 ARG   ( 107-)  A
  37 ARG   ( 118-)  A
  49 ARG   ( 130-)  A
  60 ARG   ( 141-)  A
  71 ARG   ( 152-)  A
  75 ARG   ( 156-)  A
  92 ARG   ( 172-)  A
 109 ARG   ( 189-)  A
 129 ARG   ( 209-)  A
 130 ARG   ( 210-)  A
 144 ARG   ( 224-)  A
 173 ARG   ( 253-)  A
 204 ARG   ( 284-)  A
 212 ARG   ( 292-)  A
 220 ARG   ( 300-)  A
 224 ARG   ( 304-)  A
 247 ARG   ( 327-)  A
 283 ARG   ( 364-)  A
 290 ARG   ( 371-)  A
 339 ARG   ( 419-)  A
 348 ARG   ( 428-)  A
 350 ARG   ( 430-)  A

Warning: Tyrosine convention problem

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

  19 TYR   ( 100-)  A
  74 TYR   ( 155-)  A
 127 TYR   ( 207-)  A
 175 TYR   ( 255-)  A
 331 TYR   (  12-)  A

Warning: Phenylalanine convention problem

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

   3 PHE   (  84-)  A
 161 PHE   ( 241-)  A
 177 PHE   ( 257-)  A
 372 PHE   ( 452-)  A
 387 PHE   ( 467-)  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.

   2 ASP   (  83-)  A
  30 ASP   ( 111-)  A
  32 ASP   ( 113-)  A
  44 ASP   ( 125-)  A
  46 ASP   ( 127-)  A
 163 ASP   ( 243-)  A
 213 ASP   ( 293-)  A
 226 ASP   ( 306-)  A
 244 ASP   ( 324-)  A
 258 ASP   ( 339-)  A
 275 ASP   ( 356-)  A
 320 ASP   ( 402-)  A
 330 ASP   ( 412-)  A
 354 ASP   ( 434-)  A
 377 ASP   ( 457-)  A
 380 ASP   ( 460-)  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   ( 128-)  A
  94 GLU   ( 174-)  A
 134 GLU   ( 214-)  A
 147 GLU   ( 227-)  A
 171 GLU   ( 251-)  A
 179 GLU   ( 259-)  A
 186 GLU   ( 266-)  A
 206 GLU   ( 286-)  A
 334 GLU   ( 414-)  A
 336 GLU   ( 416-)  A
 371 GLU   ( 451-)  A
 385 GLU   ( 465-)  A

Error: Decreasing residue numbers

At least one residue in each of the chains mentioned below has a residue number that is lower than the previous residue in that chain ('-' represents a chain without chain identifier).

Chain identifier(s): A

Geometric checks

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: 0.469
RMS-deviation in bond distances: 0.012

Warning: Possible cell scaling problem

Comparison of bond distances with Engh and Huber [REF] standard values for protein residues and Parkinson et al [REF] values for DNA/RNA shows a significant systematic deviation. It could be that the unit cell used in refinement was not accurate enough. The deformation matrix given below gives the deviations found: the three numbers on the diagonal represent the relative corrections needed along the A, B and C cell axis. These values are 1.000 in a normal case, but have significant deviations here (significant at the 99.99 percent confidence level)

There are a number of different possible causes for the discrepancy. First the cell used in refinement can be different from the best cell calculated. Second, the value of the wavelength used for a synchrotron data set can be miscalibrated. Finally, the discrepancy can be caused by a dataset that has not been corrected for significant anisotropic thermal motion.

Please note that the proposed scale matrix has NOT been restrained to obey the space group symmetry. This is done on purpose. The distortions can give you an indication of the accuracy of the determination.

If you intend to use the result of this check to change the cell dimension of your crystal, please read the extensive literature on this topic first. This check depends on the wavelength, the cell dimensions, and on the standard bond lengths and bond angles used by your refinement software.

Unit Cell deformation matrix

 |  0.998865  0.000095  0.000205|
 |  0.000095  0.997456 -0.000024|
 |  0.000205 -0.000024  0.998823|
Proposed new scale matrix

 |  0.005530  0.000000 -0.000001|
 |  0.000000  0.005538  0.000000|
 | -0.000001  0.000000  0.005531|
With corresponding cell

    A    = 180.823  B   = 180.568  C    = 180.815
    Alpha=  90.002  Beta=  89.976  Gamma=  90.002

The CRYST1 cell dimensions

    A    = 181.030  B   = 181.030  C    = 181.030
    Alpha=  90.000  Beta=  90.000  Gamma=  90.000

Variance: 36.581
(Under-)estimated Z-score: 4.458

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.

  44 ASP   ( 125-)  A      N    CA   C    98.34   -4.6
 146 GLN   ( 226-)  A      N    CA   C   123.35    4.3
 219 ASN   ( 299-)  A      N    CA   C    99.50   -4.2

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.

   1 ARG   (  82-)  A
   2 ASP   (  83-)  A
  26 ARG   ( 107-)  A
  30 ASP   ( 111-)  A
  32 ASP   ( 113-)  A
  37 ARG   ( 118-)  A
  44 ASP   ( 125-)  A
  46 ASP   ( 127-)  A
  47 GLU   ( 128-)  A
  49 ARG   ( 130-)  A
  60 ARG   ( 141-)  A
  71 ARG   ( 152-)  A
  75 ARG   ( 156-)  A
  92 ARG   ( 172-)  A
  94 GLU   ( 174-)  A
 109 ARG   ( 189-)  A
 129 ARG   ( 209-)  A
 130 ARG   ( 210-)  A
 134 GLU   ( 214-)  A
 144 ARG   ( 224-)  A
 147 GLU   ( 227-)  A
 163 ASP   ( 243-)  A
 171 GLU   ( 251-)  A
 173 ARG   ( 253-)  A
 179 GLU   ( 259-)  A
And so on for a total of 51 lines.

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.

 146 GLN   ( 226-)  A    4.70
  44 ASP   ( 125-)  A    4.38
  24 ALA   ( 105-)  A    4.22
 109 ARG   ( 189-)  A    4.04
 219 ASN   ( 299-)  A    4.00

Warning: High tau angle deviations

The RMS Z-score for the tau angles (N-Calpha-C) in the structure is too high. For well refined structures this number is expected to be near 1.0. The fact that it is higher than 1.5 worries us. However, we determined the tau normal distributions from 500 high-resolution X-ray structures, rather than from CSD data, so we cannot be 100 percent certain about these numbers.

Tau angle RMS Z-score : 1.593

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.

 140 ARG   ( 220-)  A    -2.9
 108 THR   ( 188-)  A    -2.7
 251 PRO   ( 331-)  A    -2.7
  37 ARG   ( 118-)  A    -2.5
 224 ARG   ( 304-)  A    -2.5
 129 ARG   ( 209-)  A    -2.5
  57 THR   ( 138-)  A    -2.4
 319 THR   ( 401-)  A    -2.3
 271 PHE   ( 352-)  A    -2.2
 145 THR   ( 225-)  A    -2.2
  89 TYR   (  69-)  A    -2.2
 101 THR   ( 181-)  A    -2.2
  68 ILE   ( 149-)  A    -2.1
 384 ILE   ( 464-)  A    -2.1
  40 TYR   ( 121-)  A    -2.1
 376 TRP   ( 456-)  A    -2.1
 360 SER   ( 440-)  A    -2.1
 351 PRO   ( 431-)  A    -2.1
 268 VAL   ( 349-)  A    -2.1
 203 GLU   ( 283-)  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.

  37 ARG   ( 118-)  A  Poor phi/psi
  38 GLU   ( 119-)  A  Poor phi/psi
  83 SER   ( 164-)  A  Poor phi/psi
  95 CYS   ( 175-)  A  Poor phi/psi
 128 ASN   ( 208-)  A  Poor phi/psi
 129 ARG   ( 209-)  A  Poor phi/psi
 145 THR   ( 225-)  A  Poor phi/psi
 147 GLU   ( 227-)  A  Poor phi/psi
 179 GLU   ( 259-)  A  Poor phi/psi
 205 ALA   ( 285-)  A  Poor phi/psi
 211 CYS   ( 291-)  A  Poor phi/psi
 216 GLN   ( 296-)  A  Poor phi/psi
 230 MET   ( 310-)  A  Poor phi/psi
 235 GLN   ( 315-)  A  Poor phi/psi
 245 ASN   ( 325-)  A  PRO omega poor
 266 ASN   ( 347-)  A  Poor phi/psi
 300 ASN   ( 381-)  A  Poor phi/psi
 322 SER   ( 404-)  A  Poor phi/psi
 350 ARG   ( 430-)  A  PRO omega poor
 360 SER   ( 440-)  A  Poor phi/psi
 chi-1/chi-2 correlation Z-score : -2.939

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!

   7 THR   (  88-)  A      0
  14 ASN   (  95-)  A      0
  22 ASP   ( 103-)  A      0
  30 ASP   ( 111-)  A      0
  31 SER   ( 112-)  A      0
  32 ASP   ( 113-)  A      0
  37 ARG   ( 118-)  A      0
  38 GLU   ( 119-)  A      0
  39 PRO   ( 120-)  A      0
  40 TYR   ( 121-)  A      0
  46 ASP   ( 127-)  A      0
  55 GLN   ( 136-)  A      0
  63 HIS   ( 144-)  A      0
  65 ASN   ( 146-)  A      0
  67 THR   ( 148-)  A      0
  68 ILE   ( 149-)  A      0
  71 ARG   ( 152-)  A      0
  80 TRP   ( 161-)  A      0
  82 LEU   ( 163-)  A      0
  83 SER   ( 164-)  A      0
  94 GLU   ( 174-)  A      0
  95 CYS   ( 175-)  A      0
  96 ILE   ( 176-)  A      0
  99 SER   ( 179-)  A      0
 101 THR   ( 181-)  A      0
And so on for a total of 227 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 : 2.194

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]

 248 PRO   ( 328-)  A    0.13 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].

  85 PRO   ( 166-)  A   -12.4 half-chair C-alpha/N (-18 degrees)
 169 PRO   ( 249-)  A  -114.3 envelop C-gamma (-108 degrees)
 251 PRO   ( 331-)  A   -60.8 half-chair C-beta/C-alpha (-54 degrees)
 379 PRO   ( 459-)  A   -63.5 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.

 395 MAN   ( 471-)  A      O6  <->  402 MAN   ( 475-)  A      C1     0.98    1.42  INTRA B3
 395 MAN   ( 471-)  A      C6  <->  402 MAN   ( 475-)  A      C1     0.86    2.34  INTRA
  92 ARG   ( 172-)  A      CD  <->  129 ARG   ( 209-)  A      NH2    0.40    2.70  INTRA
  94 GLU   ( 174-)  A      OE1 <->  129 ARG   ( 209-)  A      NH2    0.37    2.33  INTRA
  87 THR   ( 168-)  A      OG1 <->   90 ASN   ( 170-)  A      ND2    0.30    2.40  INTRA
  87 THR   ( 168-)  A      N   <->   90 ASN   ( 170-)  A      ND2    0.23    2.62  INTRA
   6 LEU   (  87-)  A      N   <->  153 HIS   ( 233-)  A      CD2    0.23    2.87  INTRA
 391 NAG   (1086-)  A      O4  <->  392 NAG   (1087-)  A      C1     0.23    2.37  INTRA BF
 104 HIS   ( 184-)  A      ND1 <->  106 GLY   ( 186-)  A      N      0.20    2.80  INTRA BL
 108 THR   ( 188-)  A      CG2 <->  127 TYR   ( 207-)  A      CZ     0.18    3.02  INTRA BL
  94 GLU   ( 174-)  A      CD  <->  129 ARG   ( 209-)  A      NH2    0.14    2.96  INTRA
  90 ASN   ( 170-)  A      CB  <->  403 HOH   (1453 )  A      O      0.13    2.67  INTRA
 191 THR   ( 271-)  A      OG1 <->  257 ASN   ( 338-)  A      ND2    0.11    2.59  INTRA
   4 ASN   (  85-)  A      ND2 <->  403 HOH   (1204 )  A      O      0.10    2.60  INTRA BL
  38 GLU   ( 119-)  A      N   <->   39 PRO   ( 120-)  A      CD     0.10    2.90  INTRA BL
 184 LYS   ( 264-)  A      NZ  <->  403 HOH   (1400 )  A      O      0.10    2.60  INTRA
  17 HIS   (  98-)  A      CE1 <->  339 ARG   ( 419-)  A      NH1    0.10    3.00  INTRA BL
 218 SER   ( 298-)  A      N   <->  219 ASN   ( 299-)  A      N      0.09    2.51  INTRA BL
 212 ARG   ( 292-)  A      NH2 <->  214 ASN   ( 294-)  A      ND2    0.09    2.76  INTRA
 219 ASN   ( 299-)  A      OD1 <->  260 TYR   ( 341-)  A      N      0.09    2.61  INTRA
 324 TYR   ( 406-)  A      OH  <->  401 DAN   (   0-)  A      C2     0.08    2.72  INTRA BL
 313 GLN   ( 395-)  A      NE2 <->  403 HOH   (1226 )  A      O      0.08    2.62  INTRA BL
  44 ASP   ( 125-)  A      N   <->   47 GLU   ( 128-)  A      O      0.08    2.62  INTRA
 324 TYR   ( 406-)  A      O   <->  345 GLU   ( 425-)  A      N      0.08    2.62  INTRA BL
  63 HIS   ( 144-)  A      CD2 <->  403 HOH   (1183 )  A      O      0.07    2.73  INTRA BL
And so on for a total of 56 lines.

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.

 375 GLN   ( 455-)  A      -6.11
 334 GLU   ( 414-)  A      -5.97
  71 ARG   ( 152-)  A      -5.67
 372 PHE   ( 452-)  A      -5.43
  74 TYR   ( 155-)  A      -5.37
  89 TYR   (  69-)  A      -5.34
 336 GLU   ( 416-)  A      -5.16
 260 TYR   ( 341-)  A      -5.04
 249 ASN   ( 329-)  A      -5.02

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.

   5 ASN   (  86-)  A   -2.70
 313 GLN   ( 395-)  A   -2.57

Warning: Abnormal packing Z-score for sequential residues

A stretch of at least four sequential residues with a 2nd generation packing Z-score below -1.75 was found. This could indicate that these residues are part of a strange loop or that the residues in this range are incomplete, but it might also be an indication of misthreading.

The table below lists the first and last residue in each stretch found, as well as the average residue Z-score of the series.

 372 PHE   ( 452-)  A     -  375 GLN   ( 455-)  A        -1.93

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.

 403 HOH   (1177 )  A      O     -0.72   16.55   60.10
 403 HOH   (1193 )  A      O      0.70   31.06   57.66
 403 HOH   (1195 )  A      O      0.35   32.03   55.11
 403 HOH   (1292 )  A      O     16.81   -2.62   45.64
 403 HOH   (1325 )  A      O     23.03   47.39   63.22
 403 HOH   (1408 )  A      O     46.25  -19.13   64.84
 403 HOH   (1487 )  A      O     24.63   29.07   33.96

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.

 403 HOH   (1359 )  A      O
 403 HOH   (1381 )  A      O
 403 HOH   (1430 )  A      O
 403 HOH   (1452 )  A      O
 403 HOH   (1481 )  A      O
 403 HOH   (1483 )  A      O
Bound group on Asn; dont flip    5 ASN  (  86-) A
Bound to:  391 NAG  (1086-) A
Bound group on Asn; dont flip   65 ASN  ( 146-) A
Bound to:  393 NAG  (1146-) A
Bound group on Asn; dont flip  120 ASN  ( 200-) A
Bound to:  389 NAG  ( 469-) A

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.

  14 ASN   (  95-)  A
  17 HIS   (  98-)  A
  63 HIS   ( 144-)  A
  69 HIS   ( 150-)  A
  90 ASN   ( 170-)  A
 136 ASN   ( 216-)  A
 214 ASN   ( 294-)  A
 232 HIS   ( 312-)  A
 311 GLN   ( 392-)  A
 313 GLN   ( 395-)  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.

   6 LEU   (  87-)  A      N
  16 TRP   (  97-)  A      NE1
  25 VAL   ( 106-)  A      N
  37 ARG   ( 118-)  A      NH2
  41 VAL   ( 122-)  A      N
  57 THR   ( 138-)  A      N
  72 SER   ( 153-)  A      N
  83 SER   ( 164-)  A      N
  87 THR   ( 168-)  A      OG1
  99 SER   ( 179-)  A      N
 116 GLY   ( 196-)  A      N
 146 GLN   ( 226-)  A      NE2
 148 SER   ( 228-)  A      N
 189 ALA   ( 269-)  A      N
 191 THR   ( 271-)  A      OG1
 194 HIS   ( 274-)  A      N
 215 TRP   ( 295-)  A      NE1
 217 GLY   ( 297-)  A      N
 245 ASN   ( 325-)  A      ND2
 247 ARG   ( 327-)  A      NH2
 258 ASP   ( 339-)  A      N
 269 LYS   ( 350-)  A      N
 279 THR   ( 360-)  A      N
 283 ARG   ( 364-)  A      NH1
 283 ARG   ( 364-)  A      NH2
 311 GLN   ( 392-)  A      N
 337 CYS   ( 417-)  A      N
 358 TRP   ( 438-)  A      N
 377 ASP   ( 457-)  A      N
 385 GLU   ( 465-)  A      N
 393 NAG   (1146-)  A      N2

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.

 196 GLU   ( 276-)  A      OE1
 232 HIS   ( 312-)  A      ND1

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+.

 399  CA   ( 999-)  A     0.49   1.41 Is perhaps  K
 400  CA   ( 998-)  A     0.31   0.66 Is perhaps  K (Few ligands (4) ) *S

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.

 403 HOH   (1298 )  A      O  1.03  K  4
 403 HOH   (1345 )  A      O  1.02  K  4
 403 HOH   (1450 )  A      O  0.90  K  4 ION-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.

 105 ASP   ( 185-)  A   H-bonding suggests Asn; but Alt-Rotamer
 163 ASP   ( 243-)  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 :  -0.720
  2nd generation packing quality :  -2.025
  Ramachandran plot appearance   :  -2.112
  chi-1/chi-2 rotamer normality  :  -2.939
  Backbone conformation          :  -1.678

RMS Z-scores, should be close to 1.0:
  Bond lengths                   :   0.469 (tight)
  Bond angles                    :   0.758
  Omega angle restraints         :   0.399 (tight)
  Side chain planarity           :   0.180 (tight)
  Improper dihedral distribution :   0.715
  B-factor distribution          :   0.758
  Inside/Outside distribution    :   1.072

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 : 1.80


Structure Z-scores, positive is better than average:

  1st generation packing quality :  -0.3
  2nd generation packing quality :  -1.5
  Ramachandran plot appearance   :  -2.1
  chi-1/chi-2 rotamer normality  :  -2.5
  Backbone conformation          :  -2.0

RMS Z-scores, should be close to 1.0:
  Bond lengths                   :   0.469 (tight)
  Bond angles                    :   0.758
  Omega angle restraints         :   0.399 (tight)
  Side chain planarity           :   0.180 (tight)
  Improper dihedral distribution :   0.715
  B-factor distribution          :   0.758
  Inside/Outside distribution    :   1.072
==============

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.