The Molecular Entity ================================================================================ .. currentmodule:: ost.mol This document describes the :class:`EntityHandle` and the related classes. The Handle Classes -------------------------------------------------------------------------------- .. function:: CreateEntity() Creates a new entity. The created entity is empty, that is, it does not contain any atoms, residues, chains, bonds or torsions. To populate the entity, use an :doc:`entity editor `. :returns: The newly created :class:`EntityHandle` .. class:: EntityHandle The entity class represents a molecular structure. Such a structure is in general made up of one or more chains of residues, which in turn are formed by one or more atoms. The interface of entities is tailored to biological macromolecules, but this does not prevent it to be used for molecules in general: An entity also represent a ligand or a collection of water molecules - hence the rather generic name. .. attribute:: chains List of all chains of this entity. The chains are in the same order they have been added, for example the order they have been listed in a PDB file. Also available as :meth:`GetChainList`. To access a single chain, use :meth:`FindChain`. This property is read-only. :type: :class:`ChainHandleList` (list of :class:`ChainHandle`) .. attribute:: chain_count Number of chains. Read-only. See :meth:`GetChainCount`. :type: :class:`int` .. attribute:: residues List of all residues of this entity. The returned residues are first sorted by chain and then from N- to C-terminus. This property is read-only. **Example usage:** .. code-block:: python for res in ent.residues: print(res.name, res.atom_count) Also available as :meth:`GetResidueList`. To access a single residue, use :meth:`FindResidue`. :type: :class:`ResidueHandleList` (list of :class:`ResidueHandle`) .. attribute:: residue_count Number of residues. Read-only. See :meth:`GetResidueCount`. :type: :class:`int` .. attribute:: atoms Get list of all atoms of this entity. To access a single atom, use :meth:`FindAtom`. This property is read-only. Also available as :meth:`GetAtomList` :type: :class:`AtomHandleList` (list of :class:`AtomHandle`) .. attribute:: atom_count Number of atoms. Read-only. See :meth:`GetAtomCount`. :type: :class:`int` .. attribute:: bounds Axis-aligned bounding box of the entity. Read-only :type: :class:`ost.geom.AlignedCuboid` .. attribute:: mass The total mass of the entity in Dalton. Also available as :meth:`GetMass`. :type: float .. attribute:: center_of_mass Center of mass. Also available as :meth:`GetCenterOfMass` :type: :class:`~ost.geom.Vec3` .. attribute:: center_of_atoms Center of atoms (not mass-weighted). Also available as :meth:`GetCenterOfAtoms`. :type: :class:`~ost.geom.Vec3` .. attribute:: positions Equivalent to calling :meth:`GetPositions` with *sort_by_index = True*. This property is read-only and only available if OpenStructure was compiled with an enabled ``USE_NUMPY`` flag (see :ref:`here ` for details). :type: :class:`numpy.array` .. attribute:: valid Validity of handle. :type: bool .. method:: GetName() :returns: Name associated to this entity. :rtype: :class:`str` .. method:: SetName(name) :param name: Sets this as new name to be associated to this entity. :type name: :class:`str` .. method:: FindChain(chain_name) Get chain by name. See also :attr:`chains` :param chain_name: Chain identifier, e.g. "A" :type chain_name: str :returns: A valid :class:`ChainHandle`, if the entity contains a chain with the given name, an invalid :class:`ChainHandle` otherwise. .. method:: GetChainList() See :attr:`chains` .. method:: GetChainCount() See :attr:`chain_count` .. method:: FindResidue(chain_name, res_num) Get residue by chain name and residue number. See also :meth:`GetResidueList` :param chain_name: Chain identifier, e.g. "A" :type chain_name: str :param res_num: residue number :type res_num: :class:`ResNum` :returns: A valid :class:`ResidueHandle` if the chain exists and the chain contains a residue of the given residue number, an invalid :class:`ResidueHandle` otherwise. .. method:: GetResidueList() See :attr:`residues` .. method:: GetResidueCount() See :attr:`residue_count` .. method:: FindAtom(chain_name, res_num, atom_name) Get atom by chain name, residue number and atom name. See also :attr:`atoms` :param chain_name: Chain identifier, e.g. "A" :type chain_name: str :param res_num: residue number :type res_num: :class:`ResNum` :param atom_name: atom name, e.g. CA :type atom_name: str :returns: A valid :class:`AtomHandle` if an atom matching the parameters could be found, an invalid :class:`AtomHandle` otherwise .. method:: GetAtomList() See :attr:`atoms` .. method:: GetAtomCount() See :attr:`atom_count` .. method:: EditXCS([edit_mode=mol.EditMode.UNBUFFERED_EDIT]) Request :class:`XCSEditor` for editing the external coordinate system. This call will fail when there are pending changes of the internal coordinate system. :param edit_mode: Must be EditMode.BUFFERED_EDIT or EditMode.UNBUFFERED_EDIT. For more details, see the editor documentation. :type edit_mode: mol.EditMode :returns: :class:`XCSEditor` .. method:: EditICS([edit_mode=mol.EditMode.UNBUFFERED_EDIT]) Request :class:`ICSEditor` for editing the internal coordinate system, such as torsions, bond lengths and angle between two bonds. This call will fail when there are pending changes of the external coordinate system. :param edit_mode: Must be EditMode.BUFFERED_EDIT or EditMode.UNBUFFERED_EDIT. For more details, see the editor documentation. :type edit_mode: mol.EditMode :returns: :class:`ICSEditor` .. method:: Select(query, flags=0) Perform a selection on the entity. The result of the selection is an :class:`EntityView` which (usually) contains only a subset of chains, residues, atoms and bonds of the original entity. **Example Usage:** .. code-block:: python # select calpha atoms of peptides calphas = ent.Select('aname=CA and peptide=true') # select atoms in a box of size 10, centred at the origin in_box = ent.Select('x=-5:5 and y=-5:5 and z=-5:5') :param query: The query to be executed. :type query: :class:`Query` / :class:`str` :param flags: An ORed together combination of :class:`QueryFlag` :type flags: :class:`int` / :class:`QueryFlag` :returns: An :class:`entity view `. :raises: :class:`QueryError` when the query could not be executed due to syntactic errors. .. method:: CreateFullView() Creates an entity view containing all chains, residues, atoms and bonds of this entity. .. code-block:: python # these two lines are identical full=ent.Select('') full=ent.CreateFullView() :returns: :class:`EntityView` .. method:: CreateEmptyView() Creates an entity view pointing to this entity, but otherwise empty. This method is usually the starting point for manual entity view creation, e.g.: .. code-block:: python view=ent.CreateEmtpyView() for atom in ent.atoms: if ComplicatedPredicate(atom): view.AddAtom(atom) :returns: :class:`EntityView` .. method:: Copy() Creates a deep copy of the entity. :returns: A new :class:`EntityHandle` that is an exact copy of this entity. .. note:: alternative atom positions are not handled yet. .. method:: GetCenterOfAtoms() Get center of atoms, that is the average atom position of the entity. Use :meth:`GetCenterOfMass` to calculate the mass-weighted center of the entity. :returns: :class:`~ost.geom.Vec3` .. method:: GetCenterOfMass() Calculates the center of mass of the entity. Use :meth:`GetCenterOfAtoms` to calculate the non-mass-weighted center of the entity. :returns: :class:`~ost.geom.Vec3` .. method:: GetGeometricCenter() Calculates the mid-point of the axis aligned bounding box of the entity. :returns: :class:`~ost.geom.Vec3` .. method:: GetMass() See :attr:`mass` .. method:: GetPositions(sort_by_index=True) :return: Array of atom positions for this entity. :rtype: :class:`numpy.array` (shape [:attr:`atom_count`, 3]) :param sort_by_index: If True, the atoms are sorted by their :attr:`~AtomHandle.index`. Otherwise, they are sorted as they appear in the :attr:`atoms` list. This method is only available if OpenStructure was compiled with an enabled ``USE_NUMPY`` flag (see :ref:`here ` for details). .. method:: FindWithin(pos, radius) Find all atoms in sphere of given radius centred at *pos*. To turn the returned list of atoms into an :class:`EntityView`, use :func:`CreateViewFromAtomList`. :param pos: Center of sphere :type pos: :class:`~ost.geom.Vec3` :param radius: The radius of the sphere :type radius: float :returns: :class:`AtomHandleList` (list of :class:`AtomHandle`) .. method:: IsValid() See :attr:`valid` .. class:: ChainHandle A chain of one or more :class:`residues `. Chains are always part of an entity. .. attribute:: atoms Get list of all atoms of this chain. To access a single atom, use :meth:`FindAtom`. This property is read-only. Also available as :meth:`GetAtomList` :type: :class:`AtomHandleList` (list of :class:`AtomHandle`) .. attribute:: bounds Axis-aligned bounding box of the chain. Read-only :type: :class:`ost.geom.AlignedCuboid` .. attribute:: center_of_atoms Center of atoms (not mass weighted). Also available as :meth:`GetCenterOfAtoms`. :type: :class:`~ost.geom.Vec3` .. attribute:: center_of_mass Center of mass. Also available as :meth:`GetCenterOfMass` :type: :class:`~ost.geom.Vec3` .. attribute:: description Details about the chain. Not categorised, just text. .. attribute:: in_sequence Whether the residue numbers are in ascending order. For example: .. code-block:: python chain=ent.FindChain("A") print(chain.residues) # [A.GLY1, A.GLY2, A.GLY4A, A.GLY4B] print(chain.in_sequence) # prints true chain=ent.FindChain("B") print(chain.residues) # [B.GLY1, B.GLY4, B.GLY3] print(chain.in_sequence) # prints false .. attribute:: is_oligosaccharide Indicates if the chain is an oligosaccharide, a branched, non-linear entity of multiple sugars. Also available as :meth:`IsOligosaccharide`. :type: :class:`bool` .. attribute:: is_polymer Indicates if a chain is a polymer. True for polypeptides, polynucleotides, polysaccharides, oligosaccharides and branched chains. Also available as :meth:`IsPolymer`. :type: :class:`bool` .. attribute:: is_polynucleotide Indicates if a chain is a nucleic acid. Also available as :meth:`IsPolynucleotide`. :type: :class:`bool` .. attribute:: is_polypeptide Indicates if a chain is a protein. Also available as :meth:`IsPolypeptide`. :type: :class:`bool` .. attribute:: is_polysaccharide Indicates if a chain is a polysaccharide. Also available as :meth:`IsPolysaccharide()`. :type: :class:`bool` .. attribute:: mass The total mass of this chain in Dalton. Also available as :meth:`GetMass` :type: float .. attribute:: name The chain name. The name uniquely identifies the chain in the entity. In most cases, the chain name is one character. This is restriction of the PDB file format. However, you are free to use longer names as long as you don't want to save them as PDB files This property is read-only. To change the name, use an :class:`XCSEditor`. Also available as :meth:`GetName` :type: str .. attribute:: residue_count Number of residues. Read-only. See :meth:`GetResidueCount`. :type: :class:`int` .. attribute:: residues List of all residues of this chain. The residues are sorted from N- to C-terminus. Usually the residue numbers are in ascending order (see :attr:`in_sequence`). This property is read-only. **Example usage:** .. code-block:: python chain=ent.FindChain("A") for res in chain.residues: print(res.name, res.atom_count) Also available as :meth:`GetResidueList`. To access a single residue, use :meth:`FindResidue`. :type: :class:`ResidueHandleList` (list of :class:`ResidueHandle`) .. attribute:: type Describes the type of the chain. :type: :class:`ChainType`. .. attribute:: valid Validity of handle. :type: bool .. method:: FindResidue(res_num) Get residue by residue number. See also :attr:`residues`. :param res_num: residue number :type res_num: :class:`ResNum` :returns: A valid :class:`ResidueHandle` if the chain contains a residue with matching residue number, an invalid :class:`ResidueHandle` otherwise. .. method:: GetResidueList() See :attr:`residues` .. method:: GetResidueCount() See :attr:`residue_count` .. method:: FindAtom(res_num, atom_name) Get atom by residue number and atom name. See also :attr:`atoms` :param res_num: residue number :type res_num: :class:`ResNum` :param atom_name: atom name, e.g. CA :type atom_name: str :returns: A valid :class:`AtomHandle` if an atom matching the parameters could be found, an invalid :class:`AtomHandle` otherwise .. method:: GetAtomList() See :attr:`atoms` .. method:: GetName() See :attr:`name` .. method:: GetType() See :attr:`type` .. method:: IsOligosaccharide() See :attr:`is_oligosaccharide` .. method:: IsPolymer() See :attr:`is_polymer` .. method:: IsPolynucleotide() See :attr:`is_polynucleotide` .. method:: IsPolypeptide() See :attr:`is_polypeptide` .. method:: IsPolysaccharide() See :attr:`is_polysaccharide` .. method:: GetDescription() See :attr:`description` .. method:: IsValid() See :attr:`valid` .. class:: ResidueHandle The residue is either used to represent complete molecules or building blocks in a polymer, e.g. in a protein, DNA or RNA. A residue consists of one or more :class:`atoms `. Residues are always part of a :class:`ChainHandle`, even if they are ligands or water molecules where the concept of a chain does not apply. .. attribute:: name The residue name is usually a str of 3 characters, e.g. `GLY` for glycine or `ALA` for alanine, but may be shorter, e.g. `G` for guanosine, or longer for structures loaded from formats other than PDB. This property is read-only. To change the name of the residue, use :meth:`EditorBase.SetResidueName`. .. attribute:: number The number of this residue. The residue number has a numeric part and an insertion-code. This property is read-only. Also available as :meth:`GetNumber`. :type: :class:`ResNum` .. attribute:: one_letter_code For amino acids, and nucleotides the `one_letter_code` is an alpha-numeric character. For unknown or more *exotic* residues, the one letter code is set to '?'. **Example** This code-snippet shows how to get the sequence string from a list of residues. .. code-block:: python print(''.join([r.one_letter_code for r in chain.residues])) :type: str .. attribute:: atoms Get list of all atoms of this residue. To access a single atom, use :meth:`FindAtom`. This property is read-only. Also available as :meth:`GetAtomList` :type: :class:`AtomHandleList` (list of :class:`AtomHandle`) .. attribute:: bounds Axis-aligned bounding box of the residue. Read-only. :type: :class:`ost.geom.AlignedCuboid` .. attribute:: mass The total mass of this residue in Dalton. Also available as :meth:`GetMass`. :type: float .. attribute:: center_of_mass Center of mass. Also available as :meth:`GetCenterOfMass` :type: :class:`~ost.geom.Vec3` .. attribute:: center_of_atoms Center of atoms (not mass weighted). Also available as :meth:`GetCenterOfAtoms`. :type: :class:`~ost.geom.Vec3` .. attribute:: chain The chain this residue belongs to. Read-only. Also available as :meth:`GetChain` :type: :class:`ChainHandle` .. attribute:: phi_torsion The PHI dihedral angle between this residue and the next. For residues that are not amino acids, residues that do not have all atoms required or residues that do not have bonds between the four atoms involved in the torsion, the PHI torsion is an invalid handle. Read-only. Also available as :meth:`GetPhiTorsion` :type: :class:`TorsionHandle` .. attribute:: psi_torsion The PSI dihedral angle between this residue and the previous. For residues that are not amino acids, residues that do not have all atoms required or residues that do not have bonds between the four atoms involved in the torsion, the PSI torsion is an invalid handle. Read-only. Also available as :meth:`GetPsiTorsion` :type: :class:`TorsionHandle` .. attribute:: chem_class The chemical class of the residue. :type: :class:`ChemClass` .. attribute:: chem_type The chemical type of the residue. The type is only properly set if a compound library is used. :type: :class:`ChemType` .. attribute:: sec_structure The secondary structure of the residue. :type: :class:`SecStructure` .. attribute:: is_ligand Whether the residue is a ligand. When loading PDB structures, this property is set based on the HET records. This also means, that this property will most likely not be set properly for all except PDB files coming from pdb.org. Also available as :meth:`IsLigand`, :meth:`SetIsLigand`. .. attribute:: is_protein Whether the residue is considered to be part of a protein. This is set when loading a structure if the residue forms a feasible peptide bond to the previous or next residue (see :meth:`~ost.conop.IsBondFeasible`). Also available as :meth:`IsProtein`, :meth:`SetIsProtein`. In contrast to :meth:`IsPeptideLinking` this excludes residues which are not connected to neighbouring residues such as CA-only residues or badly positioned ones. .. attribute:: peptide_linking Whether residue can form peptide bonds. This is determined based on :attr:`chem_class` which is set when loading the structure. :type: :class:`bool` .. attribute:: index Residue index (starting at 0) within chain. .. attribute:: central_atom Central atom used for rendering traces. For peptides, this is usually the CA atom. For nucleotides, this is usually the P atom. :type: :class:`AtomHandle` .. attribute:: central_normal Normal computed for :attr:`central_atom`. Only defined for peptides and nucleotides if all required atoms available. Otherwise, the (1,0,0) vector is returned. :type: :class:`~ost.geom.Vec3` .. attribute:: valid Validity of handle. :type: bool .. attribute:: next Residue after this one in the same chain. Invalid handle returned if there is no next residue. Residues are ordered as in :attr:`ChainHandle.residues` independently on whether they are connected or not (see :func:`InSequence` to check for connected residues). :type: :class:`ResidueHandle` .. attribute:: prev Residue before this one in the same chain. Otherwise same behaviour as :attr:`next`. :type: :class:`ResidueHandle` .. method:: FindAtom(atom_name) Get atom by atom name. See also :attr:`atoms` :param atom_name: atom name, e.g. CA :type atom_name: str :returns: A valid :class:`AtomHandle` if an atom with the given name could be found, an invalid :class:`AtomHandle` otherwise .. method:: HasAltAtoms() Returns whether the residue has any alternative atom groups :rtype: :class:`bool` .. method:: HasAltAtomGroup(group_name) Returns whether the residue has a certain alternative atom group :param group_name: Group of interest :type group_name: :class:`str` :rtype: :class:`bool` .. method:: GetAltAtomGroupNames() Returns names of all alternative atom groups in residue :rtype: :class:`list` of :class:`str` .. method:: GetCurrentAltGroupName() Returns the currently active alternative atom group, empty :class:`str` if residue has no alternative atom groups :rtype: :class:`str` .. method:: SwitchAtomPos(group_name) Switches the atoms in residue to the specified alternative atom group :param group_name: Group of interest :type group_name: :class:`str` :rtype: :class:`bool` :returns: Whether the switch was successful (e.g. False if no such group exists) .. method:: GetAtomList() See :attr:`atoms` .. method:: IsPeptideLinking() See :attr:`peptide_linking` .. method:: GetChain() See :attr:`chain` .. method:: GetCenterOfAtoms() See :attr:`center_of_atoms` .. method:: GetCenterOfMass() See :attr:`center_of_mass` .. method:: GetPhiTorsion() See :attr:`phi_torsion` .. method:: GetPsiTorsion() See :attr:`psi_torsion` .. method:: GetChemType() See :attr:`chem_type` .. method:: GetIndex() See :attr:`index` .. method:: GetCentralAtom() SetCentralAtom() See :attr:`central_atom` .. method:: GetCentralNormal() See :attr:`central_normal` .. method:: IsValid() See :attr:`valid` .. class:: AtomHandle Represents an atom in a molecular structure. Atoms are always part of a residue. .. attribute:: name The atom name, usually a capitalized string consisting of the element and an position indicator, e.g. `G1`. In general, the atom name uniquely identifies an atom within a residue. However, this is not enforced and there may be more than one atoms with the same name. :type: str .. attribute:: qualified_name The qualified name consists of the atom name as well as a unique residue identifier and chain name. For CA of a glycine with residue number 2 of chain A, the qualified name is "A.GLY2.CA". :type: str .. attribute:: element The atom's element. Note that this may return an empty string. Also available as :meth:`GetElement`. Read-only. :type: str .. attribute:: mass The atom's mass in Dalton. Also available as :meth:`GetMass`. Read-only. :type: float .. attribute:: pos The atom's position in global coordinates, transformed by the entity transformation. Also available as :meth:`GetPos`. Read-only. :type: :class:`~ost.geom.Vec3` .. attribute:: original_pos The atom's untransformed position in global coordinates. Also available as :meth:`GetOriginalPos`. Read-only. :type: :class:`~ost.geom.Vec3` .. attribute:: radius The van-der-Waals radius of the atom. Also available as :meth:`GetRadius`. Read/write. :type: float .. attribute:: occupancy The atom's occupancy in the range 0 to 1. Read/write. Also available as :meth:`GetOccupancy`, :meth:`SetOccupancy`. :type: float .. attribute:: b_factor The atom's temperature factor. Read/write. Also available as :meth:`GetBFactor`, :meth:`SetBFactor`. :type: float .. attribute:: charge The atom's charge. Also available as :meth:`GetCharge`, :meth:`SetCharge`. :type: float .. attribute:: residue The residue this atom belongs to. Read-only. :type: :class:`ResidueHandle` .. attribute:: is_hetatom Indicates whether this atom is a *HETATM*. When loading a structure from a PDB file, all non-standard aminoacid and nucleotide atoms as well as ligands are marked as HETATM. .. attribute:: bonds List of bonds this atom is involved in. The bonds are in no particular order. Also available as :meth:`GetBondList`. :type: list of :class:`bond handles` .. attribute:: index Atom index (starting at 0) within entity. :type: int .. attribute:: hash_code A unique identifier for this atom. Note that a deep copy of an entity (see :meth:`EntityHandle.Copy`) will have atoms with differing identifiers. Shallow copies of the entity preserve the identifier. Atom views on a handle have different identifiers, but the atom view handles (see :attr:`AtomView.handle`) have the same identifier. :type: int .. attribute:: valid Validity of handle. :type: bool .. method:: FindBondToAtom(other_atom) Finds and returns the bond formed between this atom and `other_atom`. If no bond exists between the two atoms, an invalid :class:`BondHandle` is returned. :param other_atom: The other atom :type other_atom: :class:`AtomHandle` :rtype: :class:`BondHandle` .. method:: GetBondCount() :rtype: int .. method:: GetBondList() See :attr:`bonds` :rtype: :class:`BondHandleList` .. method:: GetBondPartners() Get list of atoms this atom is bonded with. This method exists as a shortcut to determine all the bonding partners of an atom and avoids code like this: .. code-block:: python bond_parters=[] for bond in atom.bonds: if bond.first==atom: bond_partners.append(bond.second) else: bond_partners.append(bond.first) :rtype: :class:`AtomHandleList` .. method:: GetCharge() See :attr:`charge` :rtype: float .. method:: GetElement() See :attr:`element` :rtype: str .. method:: GetEntity() The entity this atom belongs to :rtype: :class:`EntityHandle` .. method:: GetHashCode() See :attr:`hash_code` :rtype: int .. method:: GetIndex() See :attr:`index` :rtype: int .. method:: GetMass() See :attr:`mass` :rtype: float .. method:: GetName() See :attr:`name` :rtype: str .. method:: GetOriginalPos() :rtype: :class:`~ost.geom.Vec3` .. method:: GetPos() See :attr:`pos` :rtype: :class:`~ost.geom.Vec3` .. method:: GetQualifiedName() See :attr:`qualified_name` :rtype: str .. method:: GetRadius() See :attr:`radius` :rtype: float .. method:: GetResidue() See :attr:`residue` :rtype: :class:`ResidueHandle` .. method:: IsHetAtom() See :attr:`is_hetatom` :rtype: bool .. method:: IsValid() See :attr:`valid` The View Classes -------------------------------------------------------------------------------- .. class:: EntityView An entity view represents a structural subset of an :class:`EntityHandle`. For an introduction ,see :doc:`../../intro-01`. .. attribute:: chains List of all chains of this entity. The chains are in the same order they have been added. Also available as :meth:`GetChainList`. To access a single chain, use :meth:`FindChain`. This property is read-only. :type: :class:`ChainViewList` (list of :class:`ChainView`) .. attribute:: chain_count Number of chains. Read-only. See :meth:`GetChainCount`. :type: :class:`int` .. attribute:: residues List of all residues of this entity. The returned residues are first sorted by chain and then from N- to C-terminus. This property is read-only. **Example usage:** .. code-block:: python for res in ent.residues: print(res.name, res.atom_count) Also available as :meth:`GetResidueList`. To access a single residue, use :meth:`FindResidue`. :type: :class:`ResidueViewList` (list of :class:`ResidueView`) .. attribute:: residue_count Number of residues. Read-only. See :meth:`GetResidueCount`. :type: :class:`int` .. attribute:: atoms Get list of all atoms of this entity. To access a single atom, use :meth:`FindAtom`. This property is read-only. Also available as :meth:`GetAtomList` :type: :class:`AtomViewList` (list of :class:`AtomView`) .. attribute:: atom_count Number of atoms. Read-only. See :meth:`GetAtomCount`. :type: :class:`int` .. attribute:: bounds Axis-aligned bounding box of the entity view. Read-only. :type: :class:`ost.geom.AlignedCuboid` .. attribute:: handle The underlying :class:`handle ` of the entity view. Also available as :meth:`GetHandle`. :type: :class:`EntityHandle` .. attribute:: valid Validity of view. :type: bool .. method:: GetName() :returns: :func:`~EntityHandle.GetName` of entity :attr:`handle`. :rtype: :class:`str` .. method:: SetName(name) :param name: Passed to :func:`~EntityHandle.SetName` of :attr:`handle`. :type name: :class:`str` .. method:: CreateEmptyView() See :meth:`EntityHandle.CreateEmptyView` :rtype: :class:`EntityView` .. method:: CreateFullView() Returns a copy of this entity. Provided for `duck-typing ` purposes. :rtype: :class:`EntityView` .. method:: AddChain(chain_handle[, view_add_flags]) Add chain to view. By default, only the chain is added to the view, but not its residues and atoms. This behaviour can be changed by passing in an appropriate set of `view_add_flags`. The following example just adds a chain without residues and atoms: .. code-block:: python pdb = ost.io.LoadPDB() v = pdb.CreateEmptyView() v.AddChain(pdb.chains[0]) To get the chain with residues and atoms, go like: .. code-block:: python pdb = ost.io.LoadPDB() v = pdb.CreateEmptyView() v.AddChain(pdb.chains[0], ost.mol.INCLUDE_ALL) Note that the view above still lacks bonds which can be added with the :meth:`AddAllInclusiveBonds` method. :param chain_handle: The chain handle to be added. :type chain_handle: :class:`ChainHandle` :param view_add_flags: An ORed together combination of :class:`ViewAddFlag` :type view_add_flags: :class:`int` / :class:`ViewAddFlag` :rtype: :class:`ChainView` .. method:: AddResidue(residue_handle[, view_add_flags]) Add residue to view. If the residue's chain is not already part of the view, it will be added. By default, only the residue is added, but not its atoms. This behaviour can be modified by passing in an appropriate combination of :class:`ViewAddFlag`. :param residue_handle: The residue handle to be added :type residue_handle: :class:`ResidueHandle` :param view_add_flags: An ORed together combination of :class:`ViewAddFlag` :type view_add_flags: :class:`int` / :class:`ViewAddFlag` :rtype: :class:`ResidueView` .. method:: AddAtom(atom_handle[, view_add_flags]) Add the atom to view. The chain and residue of the atom are added to the view if they haven't already been added. :param atom_handle: The atom handle :type atom_handle: :class:`AtomHandle` :param view_add_flags: An ORed together combination of :class:`ViewAddFlag` :type view_add_flags: :class:`int` / :class:`ViewAddFlag` :rtype: :class:`AtomView` .. method:: AddBond(bond_handle) Add bond to the view. :param bond_handle: Bond to be added :type bond_handle: BondHandle :returns: True if the bond has been added, false if the bond was already present in the view. :rtype: bool .. method:: AddAllInclusiveBonds() Convenience method to add all bonds to the view for which both of the bond partners are in the view. This method is useful when manually assembling views. .. method:: RemoveChain(chain) Remove chain and all its residues from the entity view. :param chain: The chain to be removed. May be invalid :type chain: ChainView .. method:: RemoveResidue(residue) Remove residue from view. :param residue: The residue to be removed. May be invalid :type residue: ResidueView .. method:: RemoveAtom(atom) Remove atom from view :param atom: The atom to be removed. May be invalid :type atom: AtomView .. method:: GetAngle(atom1, atom2, atom3) :param atom1: :type atom1: AtomHandle :param atom2: :type atom2: AtomHandle :param atom3: :type atom3: AtomHandle :rtype: float .. method:: FindWithin(pos, radius) Find all atoms that are within radius of the given position. See :meth:`EntityHandle.FindWithin`. :param pos: Center of sphere :type pos: :class:`~ost.geom.Vec3` :param radius: The radius of the sphere :type radius: float :returns: :class:`AtomHandleList` (list of :class:`AtomHandle`) .. method:: FindChain(chain_name) Find chain by name. :param chain_name: Chain identifier, e.g. "A" :type chain_name: str :returns: The chain if present in the view, an invalid :class:`ChainView` otherwise :rtype: :class:`ChainView` .. method:: FindResidue(residue) Find residue view of pointing to the given handle. :param residue: Residue handle :type residue: ResidueHandle :returns: The residue view pointing the the handle, or an invalid handle if the residue is not part of the view :rtype: :class:`ResidueView` .. method:: FindAtom(chain_name, res_num, atom_name) :param chain_name: The chain name :type chain_name: str :param res_num: The residue number :type res_num: :class:`ResNum` or :class:`int` :param atom_name: The name of the atom :type atom_name: str :rtype: :class:`AtomView` .. method:: Select(query, flags=0) Perform selection on entity view. See :meth:`EntityHandle.Select`. :param query: The query :type query: :class:`Query` / :class:`str` :param flags: An ORed together combination of :class:`QueryFlag` :type flags: :class:`int` / :class:`QueryFlag` :rtype: :class:`EntityView` .. method:: Copy() Returns a deep copy of the entity view. The effect is identical to calling .. code-block:: python the_copy=view.Select(') :rtype: :class:`EntityView` .. method:: GetMass() Get total mass of view. :rtype: float .. method:: GetCenterOfMass() Get the center of mass. For a non-mass-weighted center, see :meth:`GetCenterOfAtoms`. :rtype: :class:`~ost.geom.Vec3` .. method:: GetGeometricCenter() Get the geometric center (the center of the axis-aligned bounding box). :rtype: :class:`~ost.geom.Vec3` .. method:: GetGeometricStart() :rtype: :class:`~ost.geom.Vec3` .. method:: GetCenterOfAtoms() Calculates the center of atoms. For a mass-weighted center, use :meth:`GetCenterOfMass`. :rtype: :class:`~ost.geom.Vec3` .. method:: GetBondCount() Get number of bonds :rtype: :class:`int` .. method:: GetBondList() See :attr:`bonds` :rtype: :class:`BondHandleList` .. method:: GetHandle() See :attr:`handle` :rtype: :class:`EntityHandle` .. method:: GetGeometricEnd() :rtype: :class:`~ost.geom.Vec3` .. method:: GetChainList() See :attr:`chains` .. method:: GetChainCount() See :attr:`chain_count` .. method:: GetResidueList() See :attr:`residues` .. method:: GetResidueCount() See :attr:`residue_count` .. method:: GetAtomList() See :attr:`atoms` .. method:: GetAtomCount() See :attr:`atom_count` .. method:: IsValid() See :attr:`valid` .. class:: ChainView A view representation of a :class:`ChainHandle`. Mostly, the same functionality is provided as for the handle. .. attribute:: name The chain name. The name uniquely identifies the chain in the entity. In most cases, the chain name is one character. This is a restriction of the PDB file format. However, you are free to use longer names as long as you don't want to save them as PDB files. This property is read-only. To change the name, use an :class:`XCSEditor`. Also available as :meth:`GetName` :type: str .. attribute:: residues List of all residues of this chain. The residues are sorted from N- to C-terminus. Usually the residue numbers are in ascending order (see :attr:`in_sequence`). This property is read-only. **Example usage:** .. code-block:: python chain=ent.FindChain("A") for res in chain.residues: print(res.name, res.atom_count) Also available as :meth:`GetResidueList`. To access a single residue, use :meth:`FindResidue`. :type: :class:`ResidueViewList` (list of :class:`ResidueView`) .. attribute:: in_sequence Whether the residue numbers are in ascending order. For example: .. code-block:: python chain=ent.FindChain("A") print(chain.residues) # [A.GLY1, A.GLY2, A.GLY4A, A.GLY4B] print(chain.in_sequence) # prints true chain=ent.FindChain("B") print(chain.residues) # [B.GLY1, B.GLY4, B.GLY3] print(chain.in_sequence) # prints false .. attribute:: atoms Get list of all atoms of this chain. To access a single atom, use :meth:`FindAtom`. This property is read-only. Also available as :meth:`GetAtomList` :type: :class:`AtomViewList` (list of :class:`AtomView`) .. attribute:: bounds Axis-aligned bounding box of the chain. Read-only :type: :class:`ost.geom.AlignedCuboid` .. attribute:: mass The total mass of this chain in Dalton. Also available as :meth:`GetMass` :type: float .. attribute:: center_of_mass Center of mass. Also available as :meth:`GetCenterOfMass` :type: :class:`~ost.geom.Vec3` .. attribute:: center_of_atoms Center of atoms (not mass weighted). Also available as :meth:`GetCenterOfAtoms`. :type: :class:`~ost.geom.Vec3` .. attribute:: handle The chain handle this view points to. Also available as :meth:`GetHandle`. :type: :class:`ChainHandle` .. attribute:: in_sequence Whether the residue numbers are in ascending order. Note that the value of `in_sequence` is independent from the value of :attr:`ChainHandle.in_sequence`. :type: bool .. attribute:: geometric_center Mid-point of the axis aligned bounding box of the entity. :type: Vec3 .. attribute:: valid Validity of view. :type: bool .. method:: AddAtom(atom_handle[, view_add_flags]) Add atom to the view. If the residue of the atom is not already part of the view, it will be added. If the atom does not belong to chain, the result is undefined. :param atom_handle: The atom to be added :type atom_handle: :class:`AtomHandle` :param view_add_flags: An ORed together combination of :class:`ViewAddFlag` :type view_add_flags: :class:`int` / :class:`ViewAddFlag` :rtype: :class:`AtomView` .. method:: AddResidue(residue_handle[, view_add_flags]) Add residue to the view. If the atom does not belong to chain, the result is undefined. By default, only the residue, but no atoms are added to the view. To change the behavior, pass in a suitable combination of :class:`ViewAddFlag`. :param residue_handle: The residue handle to be added. :type residue_handle: :class:`ResidueHandle` :param view_add_flags: An ORed together combination of :class:`ViewAddFlag` :type view_add_flags: :class:`int` / :class:`ViewAddFlag` :rtype: :class:`ResidueView` .. method:: FindAtom(res_num, atom_name) Find atom with the given residue number and atom name. :param res_num: The residue number :type res_num: :class:`ResNum` :param atom_name: The atom name :type atom_name: str :returns: The atom view, or an invalid atom view if no atom with the given parameters is part of the view. :rtype: :class:`AtomView` .. method:: FindResidue(res_num) Find residue by residue number. :param res_num: :type res_num: :class:`ResNum` :rtype: :class:`ResidueView` :returns: The residue view, or an invalid residue view if no residue with the given residue number is in the view. .. method:: GetCenterOfAtoms() See :attr:`center_of_atoms` .. method:: GetCenterOfMass() See :attr:`center_of_mass` .. method:: GetEntity() The parent entity. .. method:: GetGeometricCenter() See :attr:`geometric_center` .. method:: GetHandle() See :attr:`handle` .. method:: GetMass() See :attr:`mass` .. method:: GetName() See :attr:`name` .. method:: GetResidueByIndex(index) Returns the residue view at `index`. If index is negative or bigger than the number of residues minus one, an invalid ResidueView is returned. :param index: The index :type index: int :rtype: :class:`ResidueView` .. method:: GetResidueList() See :attr:`residues` .. method:: InSequence() See :attr:`in_sequence` .. method:: IsValid() See :attr:`valid` .. method:: RemoveResidue(residue) Remove residue from chain. If the residue is not part of the view, the chain is left unchanged. :param residue: The residue view. May be invalid :type residue: :class:`ResidueView` :rtype: None .. method:: RemoveResidues() Remove all residues from this chain view .. method:: Select(query, flags=0) Perform query on chain view. See :meth:`EntityHandle.Select`. :param query: The query :type query: :class:`Query` / :class:`str` :param flags: An ORed together combination of :class:`QueryFlag` :type flags: :class:`int` / :class:`QueryFlag` :rtype: :class:`EntityView` .. class:: ResidueView A view representation of a :class:`ResidueHandle`. Mostly, the same functionality is provided as for the handle. .. attribute:: handle The residue handle this view points to. Also available as :meth:`GetHandle`. :type: :class:`ResidueHandle` .. attribute:: name The residue name is usually a str of 3 characters, e.g. `GLY` for glycine or `ALA` for alanine, but may be shorter, e.g. `G` for guanosine, or longer for structures loaded from formats other than PDB. This property is read-only. To change the name of the residue, use :meth:`EditorBase.SetResidueName`. .. attribute:: number The number of this residue. The residue number has a numeric part and an insertion-code. This property is read-only. Also available as :meth:`GetNumber`. :type: :class:`ResNum` .. attribute:: one_letter_code For amino acids, and nucleotides the `one_letter_code` is an alpha-numeric character. For unknown or more *exotic* residues, the one letter code is set to '?'. **Example** This code-snippet shows how to get the sequence string from a list of residues. .. code-block:: python print(''.join([r.one_letter_code for r in chain.residues])) :type: str .. attribute:: bounds Axis-aligned bounding box of the residue view. Read-only :type: :class:`ost.geom.AlignedCuboid` .. attribute:: mass The total mass of this residue in Dalton. Also available as :meth:`GetMass`. :type: float .. attribute:: center_of_mass Center of mass. Also available as :meth:`GetCenterOfMass` :type: :class:`~ost.geom.Vec3` .. attribute:: center_of_atoms Center of atoms (not mass weighted). Also available as :meth:`GetCenterOfAtoms`. :type: :class:`~ost.geom.Vec3` .. attribute:: chain The chain this residue belongs to. Read-only. Also available as :meth:`GetChain` :type: :class:`ChainView` .. attribute:: handle The residue handle this view points to :type: :class:`ResidueHandle` .. attribute:: atoms Get list of all atoms of this residue. To access a single atom, use :meth:`FindAtom`. This property is read-only. Also available as :meth:`GetAtomList` :type: :class:`AtomHandleList` (list of :class:`AtomHandle`) .. attribute:: index Residue index (starting at 0) within chain view. .. method:: RemoveAtom(atom_view) Remove atom from residue and all associated bonds. If the atom is not part of the view, the residue view is left unchanged. :param atom_view: The atom to be removed. May be an invalid handle :type atom_view: :class:`AtomView` :rtype: None .. method:: GetHandle() See :attr:`handle` .. method:: GetMass() See :attr:`mass` .. method:: GetChain() See :attr:`chain` .. method:: FindAtom(atom_name) Find atom by name. Returns the atom, or an invalid atom if no atoms with the given name is part of the view. :param atom_name: :type atom_name: str :rtype: :class:`AtomView` .. method:: GetIndex() See :attr:`index` .. method:: GetCenterOfMass() See :attr:`center_of_mass` .. method:: IsAtomIncluded(atom_handle) Returns true if the given atom is part of the view, false if not. :param atom_handle: :type atom_handle: :class:`AtomHandle` :rtype: bool .. method:: GetGeometricCenter() See :attr:`geometric_center` .. method:: AddAtom(atom_handle[, flags]) Add atom to the view. :param atom_handle: Atom handle to be added :type atom_handle: :class:`AtomHandle` :param flags: An ORed together combination of :class:`ViewAddFlag` :type flags: :class:`int` / :class:`ViewAddFlag` :rtype: :class:`AtomView` .. method:: GetCenterOfAtoms() See :attr:`center_of_atoms` .. method:: GetAtomList() See :attr:`atoms` .. method:: Select(query, flags=0) Perform selection on residue view. See :meth:`EntityHandle.Select`. :param query: The query :type query: :class:`Query` / :class:`str` :param flags: An ORed together combination of :class:`QueryFlag` :type flags: :class:`int` / :class:`QueryFlag` :rtype: :class:`EntityView` .. class:: AtomView A view representation of an :class:`AtomHandle`. Mostly, the same functionality is provided as for the handle. .. attribute:: handle The underlying :class:`AtomHandle` of the atom view. Also available as :meth:`GetHandle`. :type: :class:`AtomHandle` .. attribute:: hash_code A unique identifier for this atom view. Note, that this is not the same as for the atom handle (see :attr:`AtomHandle.hash_code`). :type: int .. method:: GetHandle() See :attr:`handle` .. method:: GetHashCode() See :attr:`hash_code` Functions -------------------------------------------------------------------------------- Boolean Operators ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ .. function:: Intersection(view_a, view_b) Calculates and returns the intersection of `view_a` and `view_b`. `view_a` and `view_b` must be views of the same entity. :param view_a: first view :type view_a: EntityView :param view_b: second view :type view_b: EntityView .. function:: Difference(view_a, view_b) Calculates and returns the difference between `view_a` and `view_b`. `view_a` and `view_b` must be views of the same entity.The returned view will contain atoms, residues, chains and bonds that are in `view_a` and not in `view_b`. :param view_a: first view :type view_a: EntityView :param view_b: second view :type view_b: EntityView .. function:: Union(view_a, view_b) Calculates and returns the union of `view_a` and `view_b`. `view_a` and `view_b` must be views of the same entity.The returned view will contain all atoms, residues, chains and bonds that are either in `view_a`, `view_b` or part of both views. :param view_a: first view :type view_a: EntityView :param view_b: second view :type view_b: EntityView Other Entity-Related Functions ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ .. function:: CreateViewFromAtomList(atom_list) Returns a view made up of the atoms in *atom_list*. All atoms are required to be atoms of the same entity. Duplicate atoms are only added to the view once. :param atom_list: the atoms :type atom_list: :class:`AtomHandleList` or :class:`AtomViewList` :raises: :class:`IntegrityError` if atoms of different entities are encountered :returns: :class:`EntityView` .. function:: CreateEntityFromView(view, include_exlusive_atoms, \ handle=EntityHandle()) This function behaves exactly like :meth:`EntityHandle.Copy`, except that only atoms, residues, chains and bonds that are present in the view will be copied. :param view: is the view to be converted to a handle :param include_exlusive_atoms: if true, atoms that are part of an exclusive bond (only one bond partner is included in the view) will also be included in the new entity handle. :param handle: If invalid a new entity will be created. If valid, the atoms, residues, chains, bonds and torsions will be added to handle. This is useful to combine several entities into one. :returns: :class:`EntityHandle` .. function:: InSequence(res, res_next) :return: True, if both *res* and *res_next* are :attr:`~ResidueHandle.valid`, *res_next* is the residue following *res* (see :attr:`ResidueHandle.next`), both residues are linking (i.e. :attr:`~ChemClass.IsPeptideLinking` or :attr:`~ChemClass.IsNucleotideLinking`) and are connected by an appropriate bond. :rtype: :class:`bool` :param res: First residue to check. :type res: :class:`ResidueHandle` :param res_next: Second residue to check. :type res_next: :class:`ResidueHandle` .. function:: BondExists(atom_a, atom_b) :return: True, if *atom_a* and *atom_b* are connected by a bond. :rtype: :class:`bool` :param atom_a: First atom to check. :type atom_a: :class:`AtomHandle` :param atom_b: Second atom to check. :type atom_b: :class:`AtomHandle` Residue Numbering -------------------------------------------------------------------------------- .. class:: ResNum(num, ins_code='\\0') Number for a residue. The residue number has a numeric part and an (optional) insertion-code. You can work with this object as if it was an integer and comparison will look first at the numeric part and then the insertion-code. All access to existing objects is read-only. Openstructure supports a range of (-8388608 to 8388607) for the numeric part. However, the PDB format only supports a range of (-999, 9999). This becomes relevant when a structure is saved in PDB format where an IOException is raised if the PDB range is not respected. :param num: Numeric part of residue number. :type num: :class:`int` :param ins_code: Alpha-numeric part of residue number (optional insertion code). Only first character kept. :type ins_code: :class:`str` .. attribute:: num Numeric part of residue number. :type: :class:`int` .. attribute:: ins_code Alpha-numeric part of residue number (insertion code). Single character. :type: :class:`str` .. method:: GetNum :returns: :attr:`num` .. method:: GetInsCode :returns: :attr:`ins_code` ChainType -------------------------------------------------------------------------------- A ChainType fills the :attr:`ChainHandle.type` attribute. Different types are described in the :class:`ChainType` enum. The type is set with an editor in :meth:`EditorBase.SetChainType`. Further convenience functions are described here. .. class:: ChainType The ChainType enum enumerates all types defined by the PDB for the MMCif file format. Following values are supported: ``CHAINTYPE_POLY``, ``CHAINTYPE_NON_POLY``, ``CHAINTYPE_WATER``, ``CHAINTYPE_POLY_PEPTIDE_D``, ``CHAINTYPE_POLY_PEPTIDE_L``, ``CHAINTYPE_POLY_DN``, ``CHAINTYPE_POLY_RN``, ``CHAINTYPE_POLY_SAC_D``, ``CHAINTYPE_POLY_SAC_L``, ``CHAINTYPE_POLY_DN_RN``, ``CHAINTYPE_UNKNOWN``, ``CHAINTYPE_MACROLIDE``, ``CHAINTYPE_CYCLIC_PSEUDO_PEPTIDE``, ``CHAINTYPE_POLY_PEPTIDE_DN_RN``, ``CHAINTYPE_BRANCHED``, ``CHAINTYPE_OLIGOSACCHARIDE``, ``CHAINTYPE_N_CHAINTYPES`` Where ``CHAINTYPE_N_CHAINTYPES`` holds the number of different types available. .. function:: ChainTypeFromString(identifier) Create a ChainType item for a given string. :param identifier: String to request a type for. :type identifier: :class:`str` :raises: :class:`runtime_error` if **identifier** is unrecognised. :returns: :class:`ChainType` .. function:: StringFromChainType(type) Return the String identifier for a given **type**. :param type: To be translated :type type: :class:`ChainType` :raises: :class:`runtime_error` if **type** is unrecognised. :returns: :class:`str` ViewAddFlag -------------------------------------------------------------------------------- .. class:: ViewAddFlag Defines flags controlling behaviour of routines adding handles to views: * ``INCLUDE_ATOMS`` - Include all atoms when adding a residue handle to a view * ``INCLUDE_RESIDUES`` - Include all residues when adding a chain to a view * ``INCLUDE_CHAINS`` - Include all chains when creating a new entity view * ``INCLUDE_ALL`` = ``INCLUDE_ATOMS`` | ``INCLUDE_RESIDUES`` | ``INCLUDE_CHAINS`` - Convenience flags to include all substructures * ``CHECK_DUPLICATES`` - If set, it will be checked that no duplicates are created when adding a new handle Flags can be ORed to combine them. SecStructure -------------------------------------------------------------------------------- .. class:: SecStructure(type) Defines a secondary structure type following the types defined by DSSP. :param type: Type to be set for this object. :type type: :class:`SecStructure.Type` / :class:`str` .. method:: IsHelical :return: True, if the set type is any type of helix (i.e. ALPHA_HELIX, PI_HELIX or THREE_TEN_HELIX) .. method:: IsExtended :return: True, if the set type is any type of beta sheet (i.e. EXTENDED, BETA_BRIDGE) .. method:: IsCoil :return: True, if the set type is any type of coil (i.e. TURN, BEND or COIL) .. method:: __str__ :return: The character corresponding to the set type (see :class:`SecStructure.Type`) .. class:: SecStructure.Type Enumerates all popssible secondary structure types distinguished by DSSP. Their values with the corresponding character code are listed here: .. hlist:: :columns: 2 * ``ALPHA_HELIX`` = 'H' * ``PI_HELIX`` = 'I' * ``THREE_TEN_HELIX`` = 'G' * ``EXTENDED`` = 'E' * ``BETA_BRIDGE`` = 'B' * ``TURN`` = 'T' * ``BEND`` = 'S' * ``COIL`` = 'C' ChemClass -------------------------------------------------------------------------------- .. class:: ChemClass(chem_class) The chemical class is used to broadly categorize residues based on their chemical properties. For example, peptides belong to some PEPTIDE_LINKING class. Possible values as constant variable names and as characters: .. hlist:: :columns: 2 * ``PEPTIDE_LINKING`` = 'P' * ``D_PEPTIDE_LINKING`` = 'D' * ``L_PEPTIDE_LINKING`` = 'L' * ``RNA_LINKING`` = 'R' * ``DNA_LINKING`` = 'S' * ``NON_POLYMER`` = 'N' * ``L_SACCHARIDE`` = 'X' * ``D_SACCHARIDE`` = 'Y' * ``SACCHARIDE`` = 'Z' * ``WATER`` = 'W' * ``UNKNOWN`` = 'U' The constants are defined directly within the :mod:`mol` module. Python can implicitly convert characters to objects of this type. Note however that only the first character of a :class:`str` object is considered! :param chem_class: Chemical class to set. :type chem_class: :class:`str` .. method:: IsPeptideLinking :return: True, if set class is PEPTIDE_LINKING, D_PEPTIDE_LINKING or L_PEPTIDE_LINKING .. method:: IsNucleotideLinking :return: True, if set class is RNA_LINKING or DNA_LINKING ChemType -------------------------------------------------------------------------------- .. class:: ChemType The chemical type of a residue is a classification of all compounds obtained from the PDB component dictionary. For example, ions belong to the class IONS, amino acids to AMINOACIDS. Possible values as constant variable names and as characters: .. hlist:: :columns: 2 * ``IONS`` = 'I' * ``NONCANONICALMOLS`` = 'M' * ``SACCHARIDES`` = 'S' * ``NUCLEOTIDES`` = 'N' * ``AMINOACIDS`` = 'A' * ``COENZYMES`` = 'E' * ``WATERCOORDIONS`` = 'C' * ``DRUGS`` = 'D' * ``WATERS`` = 'W' * ``UNKNOWN`` = 'U' Python can implicitly convert characters to objects of this type. Note however that only the first character of a :class:`str` object is considered! :param chem_type: Chemical type to set. :type chem_type: :class:`str` .. method:: IsIon :return: True, if set type is IONS or WATERCOORDIONS .. method:: IsNucleotide :return: True, if set type is NUCLEOTIDES .. method:: IsSaccharide :return: True, if set type is SACCHARIDES .. method:: IsAminoAcid :return: True, if set type is AMINOACIDS .. method:: IsCoenzyme :return: True, if set type is COENZYMES .. method:: IsDrug :return: True, if set type is DRUGS .. method:: IsNonCanonical :return: True, if set type is NONCANONICALMOLS .. method:: IsWater :return: True, if set type is WATERS .. method:: IsKnown :return: True, if set type is not UNKNOWN