IO Profiles for entity importer¶

Basic usage of IO profiles¶

You are most certainly reading this document because you were having trouble loading PDB files. In that case, as a first step you will want to set the profile parameter of LoadPDB(). The profile parameter can either be the name of a profile or an instance of IOProfile. Both of the following two examples are equivalent:

ent = io.LoadPDB('weird.pdb', profile=io.profiles['SLOPPY'])
ent = io.LoadPDB('weird.pdb', profile='SLOPPY')

Profiles is a dictionary-like object containing all the profiles known to OpenStructure. You can add new ones by inserting them into the dictionary. If you are loading a lot of structures, you may want to set the default profile to avoid having to pass the profile every time you load a structure. This is done by assigning a different profile to DEFAULT:

io.profiles['DEFAULT']='SLOPPY'
ent = io.LoadPDB('weird.pdb')

Again, you can either assign the name of the profile, or the profile itself. If none of the profiles available by default suits your needs, feel free to create one to your liking.

Available default profiles¶

The following profiles are available by default. For a detailed description of what the different parameters mean, consult the documentation of IOProfile.

STRICT

This profile is the default (also available as DEFAULT) and is known to work very well with PDB files coming from the official PDB website. It is equivalent to the following profile:

IOProfile(dialect='PDB', fault_tolerant=False, quack_mode=False,
          processor=conop.RuleBasedProcessor(conop.GetDefaultLib()))

SLOPPY:

This profile loads essentially everything

IOProfile(dialect='PDB', fault_tolerant=True, quack_mode=True,
          processor=conop.RuleBasedProcessor(conop.GetDefaultLib()))

CHARMM:

This format is the default when importing CHARMM trajectories and turns on the CHARMM specific compound dictionary.

IOProfile(dialect='CHARMM', fault_tolerant=True, quack_mode=False,
          processor=conop.RuleBasedProcessor(conop.GetDefaultLib()))

The IOProfile Class¶

class IOProfile(dialect='PDB', quack_mode=False, fault_tolerant=False, join_spread_atom_records=False, no_hetatms=False, calpha_only=False, read_conect=False, processor=None)¶

Aggregates flags that control the import of molecular structures.

dialect¶

Type:

str

The dialect to be used for PDB files. At the moment, this is either CHARMM or PDB. More will most likely come in the future. By setting the dialect to CHARMM, the loading is optimized for CHARMM PDB files. This turns on support for chain names with length up to 4 characters (column 72-76) and increase the size of the residue name to 4 residues.

quack_mode¶

Type:

bool

Read/write property. When quack_mode is enabled, the chemical class for unknown residues is guessed based on its atoms and connectivity. Turn this on if you are working with non-standard conforming PDB files and are experiencing problems with the rendering of the backbone trace and/or see peptidic residues with unknown chemical classes.

fault_tolerant¶

Type:

bool

If true, the import will succeed, even if the PDB contains faulty records. The faulty records will be ignored and import continues as if the records are not present.

join_spread_atom_records¶

Type:

bool

If set to true, atom records belonging to the same residue are joined, even if they do not appear sequentially in the PDB file.

no_hetatms¶

Type:

bool

If set to true, HETATM records are ignored during import.

calpha_only¶

Type:

bool

When set to true, forces the importer to only load atoms named CA. This is most useful in combination with protein-only PDB files to speed up subsequent processing and importing.

read_conect¶

Type:

bool

Only relevant when reading files in PDB format. When set to true, reads CONECT statements and applies them in the PDB reader. This can result in hydrogen bonds, salt bridges etc. to be connected. Check the PDB format definition for more info. This may cause issues in subsequent processing, such as bonds being overriden, or extra, inconsistent bonds, as the processor suddenly has two separate sources of connectivity. For the use case where the input PDB file contains valid CONECT statements for all hetatms, you may want to disable processing of bonds between them in ost.conop.Processor.connect_hetatm

processor¶

Type:

ost.conop.HeuristicProcessor/ost.conop.RuleBasedProcessor

Controls connectivity processing of loaded ost.mol.EntityHandle. Even though its a keyword argument, processing will fail if not given.