Editing ValidatorDB:Database contents (section)

=Complete structures=
[[File:VDB chirality.png|thumb|right|400px| Complete structures can contain chirality issues on a variety of different atom types, here all possible cases occuring in '''ValidatorDB''' are illustrated.]]

If no issue was found during the ''completeness'' analyses, the validated molecule is marked as ''complete'', because it contains all the atoms which are present in the model. ''Chirality'' is further evaluated only for these molecules with ''complete structure'', because the absence of some atoms can make it difficult to check the chirality of the remaining atoms.

==Wrong chirality==
'''ValidatorDB''' and '''MotiveValidator''' present the results of several kinds of ''chirality'' analyses. If an issue is found, the following types of results are reported:
** '''Wrong chirality (Carbon)''': the chirality error was found on an sp3 hybridized carbon atom.
** '''Wrong chirality (Planar)''': the chirality error was found on a planar chiral center. Because of their spacial distribution, planar chiral centers are very sensitive even to small perturbations in the position of the substituents. Therefore, some of the errors reported here might not be significant.
** '''Wrong chirality (Metal)''': the chirality error was found on a metal chiral center. 
** '''Wrong chirality (High order)''': the chirality error was detected on a chiral atom (e.g., phosphorus) where at least one substituent is bound by a bond of higher order. 
** '''Other''': Additional chirality issue which could not be listed in any of the above categories (e.g., chirality issues on nitrogen atoms). These appear rarely in the Protein Data Bank (<0.5% of molecules).

If any issue is detected on any atom during any ''chirality'' analysis, the molecule is marked as having ''wrong chirality'', because there is at least one atom in the validated molecule with different chirality than the corresponding atom in the model. If more atoms in a molecule exhibit the same type of chirality issue, the validated molecule is counted only once in each type of statistics (e.g., if 3 carbon atoms in one glucose molecule have wrong chirality, this glucose molecule will contribute only once to the statistics on "wrong chirality (carbon)"). If a validated molecule exhibits issues in more than one type of ''chirality'' analysis, it will be counted once in each corresponding statistics (e.g., heme molecules may appear both in the statistics for ''wrong chirality (planar)'', and for the ''wrong chirality (metal)'').

==Correct chirality==
If no issues are detected during the ''chirality'' analyses, the validated molecule is marked as having '''correct chirality''', because it contains all atoms present in the model, and each of these atoms has the same chirality in the validated molecule and in the model.

Some types of chirality errors do not constitute real issues, but are artifacts of the automated chirality determination procedure. Specifically, an error in planar chirality may just mean that the chiral atom is situated slightly above or below the plane compared to its equivalent in the model from wwPDB CCD. Further, an error in high order chirality often marks the involvement of phosphate O atoms in salt or ester formation, or merely a different PDB format identification of phosphate O atoms of the validated molecule compared to the model. Therefore, if the validated molecule is found to have planar or high order chirality errors, but no other type of chirality issues, the molecule is marked as having '''correct chirality (tolerant)'''.
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