---
title: "Get chemical component (ligands, small molecules and monomers) by CCD ID."
method: GET
path: "/rest/v1/core/chemcomp/{comp_id}"
tags: ["Chemical Component Service"]
---

# Get chemical component (ligands, small molecules and monomers) by CCD ID.

`GET /rest/v1/core/chemcomp/{comp_id}`

## Request

- Base URL: `https://data.rcsb.org`
- URL: `https://data.rcsb.org/rest/v1/core/chemcomp/{comp_id}`
- Auth: none declared
- TypeScript: <https://skmtc.dev/rcsb/apis/rcsb-pdb-data-api/docs/rest/v1/core/chemcomp/:comp_id/get.ts> (a function with typed inputs; its response is checked against the schema)

## Path parameters

- `comp_id` string, required

## Response `200`

OK

- CoreChemComp
  - `chem_comp` ChemComp
    - `formula` string: The formula for the chemical component. Formulae are written according to the following rules: (1) Only recognized element symbols may be used. (2) Each element symbol is followed by a 'count' number. A count of '1' may be omitted. (3) A space or parenthesis must separate each cluster of (element symbol + count), but in general parentheses are not used. (4) The order of elements depends on whether carbon is present or not. If carbon is present, the order should be: C, then H, then the other elements in alphabetical order of their symbol. If carbon is not present, the elements are listed purely in alphabetic order of their symbol. This is the 'Hill' system used by Chemical Abstracts.
    - `formula_weight` number, double: Formula mass of the chemical component.
    - `id` string, required: The value of _chem_comp.id must uniquely identify each item in the CHEM_COMP list. For protein polymer entities, this is the three-letter code for the amino acid. For nucleic acid polymer entities, this is the one-letter code for the base.
    - `mon_nstd_parent_comp_id` string[]: The identifier for the parent component of the nonstandard component. May be be a comma separated list if this component is derived from multiple components. Items in this indirectly point to _chem_comp.id in the CHEM_COMP category.
    - `name` string: The full name of the component.
    - `one_letter_code` string: For standard polymer components, the one-letter code for the component. For non-standard polymer components, the one-letter code for parent component if this exists; otherwise, the one-letter code should be given as 'X'. Components that derived from multiple parents components are described by a sequence of one-letter-codes.
    - `pdbx_ambiguous_flag` string: A preliminary classification used by PDB to indicate that the chemistry of this component while described as clearly as possible is still ambiguous. Software tools may not be able to process this component definition.
    - `pdbx_formal_charge` integer: The net integer charge assigned to this component. This is the formal charge assignment normally found in chemical diagrams.
    - `pdbx_initial_date` string, date-time: Date component was added to database.
    - `pdbx_modified_date` string, date-time: Date component was last modified.
    - `pdbx_pcm` 'N' | 'Y': A flag to indicate if the CCD can be used to represent a protein modification.
    - `pdbx_processing_site` 'EBI' | 'PDBC' | 'PDBE' | 'PDBJ' | 'RCSB': This data item identifies the deposition site that processed this chemical component defintion.
    - `pdbx_release_status` 'DEL' | 'HOLD' | 'HPUB' | 'OBS' | 'REF_ONLY' | 'REL': This data item holds the current release status for the component.
    - `pdbx_replaced_by` string: Identifies the _chem_comp.id of the component that has replaced this component.
    - `pdbx_replaces` string: Identifies the _chem_comp.id's of the components which have been replaced by this component. Multiple id codes should be separated by commas.
    - `pdbx_subcomponent_list` string: The list of subcomponents contained in this component.
    - `three_letter_code` string: For standard polymer components, the common three-letter code for the component. Non-standard polymer components and non-polymer components are also assigned three-letter-codes. For ambiguous polymer components three-letter code should be given as 'UNK'. Ambiguous ions are assigned the code 'UNX'. Ambiguous non-polymer components are assigned the code 'UNL'.
    - `type` 'D-beta-peptide, C-gamma linking' | 'D-gamma-peptide, C-delta linking' | 'D-peptide COOH carboxy terminus' | 'D-peptide NH3 amino terminus' | 'D-peptide linking' | 'D-saccharide' | 'D-saccharide, alpha linking' | 'D-saccharide, beta linking' | 'DNA OH 3 prime terminus' | 'DNA OH 5 prime terminus' | 'DNA linking' | 'L-DNA linking' | 'L-RNA linking' | 'L-beta-peptide, C-gamma linking' | 'L-gamma-peptide, C-delta linking' | 'L-peptide COOH carboxy terminus' | 'L-peptide NH3 amino terminus' | 'L-peptide linking' | 'L-saccharide' | 'L-saccharide, alpha linking' | 'L-saccharide, beta linking' | 'RNA OH 3 prime terminus' | 'RNA OH 5 prime terminus' | 'RNA linking' | 'non-polymer' | 'other' | 'peptide linking' | 'peptide-like' | 'saccharide': For standard polymer components, the type of the monomer. Note that monomers that will form polymers are of three types: linking monomers, monomers with some type of N-terminal (or 5') cap and monomers with some type of C-terminal (or 3') cap.
  - `pdbx_chem_comp_atom_coordination` PdbxChemCompAtomCoordination[]
    - `atom_id` string: The identifier for the target atom to which the feature is assigned.
    - `geometry_generic` 'ball' | 'bent' | 'cubic' | 'cubic with vacancy' | 'cuboctahedral' | 'dodecahedral' | 'hexagonal bipyramidal' | 'hexagonal bipyramidal with axial vacancy' | 'hexagonal bipyramidal with equatorial vacancy' | 'hexagonal planar' | 'irregular' | 'linear' | 'linear bicapped' | 'linear monocapped' | 'octahedral' | 'octahedral cis bicapped' | 'octahedral edge monocapped' | 'octahedral face monocapped' | 'octahedral monocapped with capped face vacancy' | 'octahedral monocapped with non-capped face vacancy' | 'octahedral trans bicapped' | 'paired octahedral' | 'penta trigonal planar' | 'penta trigonal planar i' | 'penta trigonal planar i i' | 'penta trigonal planar v' | 'pentagonal antiprismatic' | 'pentagonal bipyramidal' | 'pentagonal bipyramidal with axial vacancy' | 'pentagonal bipyramidal with equatorial vacancy' | 'pentagonal prismatic' | 'pyramidal' | 'sandwich 4 2' | 'sandwich 4 3' | 'sandwich 4h 2' | 'sandwich 4h 3' | 'sandwich 4h 4' | 'sandwich 4h 4h' | 'sandwich 5 1' | 'sandwich 5 2' | 'sandwich 5 3' | 'sandwich 5 4' | 'sandwich 5 4 i' | 'sandwich 5 4h' | 'sandwich 5 4h v' | 'sandwich 5 5' | 'sandwich 5 5 4' | 'sandwich 5 5 i' | 'sandwich 5 5 star' | 'sandwich 5 5 v' | 'sandwich 5 5 v i' | 'sandwich 5 5 v v' | 'sandwich 5 5 v v 3d' | 'sandwich 5 5o' | 'sandwich 5 capped 1' | 'sandwich 5 hexagonal pyramidal' | 'sandwich 5 pentagonal pyramidal' | 'sandwich 5 square pyramidal' | 'sandwich 5 square pyramidal monocapped' | 'sandwich 5 tricapped i' | 'sandwich 5 tricapped v' | 'sandwich 5h 3' | 'sandwich 6 1' | 'sandwich 6 2' | 'sandwich 6 3' | 'sandwich 6 4' | 'sandwich 6 5' | 'sandwich 6 5 v' | 'sandwich 6 6' | 'sandwich 6 6 triangle' | 'sandwich 6 6 v' | 'sandwich 6 trigonal pyramidal' | 'sandwich 7 1' | 'sandwich 7 2' | 'sandwich 7 3' | 'sandwich 7 5' | 'sandwich 8 3' | 'sandwich 8 4' | 'sandwich 8 5' | 'sandwich 8 5 i' | 'sandwich 8 8' | 'sandwich 8 8 i' | 'sandwich 8 8 v' | 'sandwich c5 5 i' | 'seamine' | 'square antiprismatic' | 'square antiprismatic bicapped' | 'square antiprismatic monocapped' | 'square antiprismatic with vacancy' | 'square non-planar' | 'square planar' | 'square planar bicapped' | 'square planar monocapped' | 'square pyramidal' | 'square pyramidal with vacancy' | 't shape' | 'tetrahedral' | 'trigonal bipyramidal' | 'trigonal bipyramidal with vacancy' | 'trigonal planar' | 'trigonal planar bicapped' | 'trigonal planar monocapped' | 'trigonal planar tricapped' | 'trigonal prism tricapped' | 'trigonal prismatic' | 'trigonal prismatic all face capped' | 'trigonal prismatic monocapped' | 'trigonal prismatic monocapped with capped face vacancy' | 'trigonal prismatic monocapped with non-capped face vacancy' | 'trigonal prismatic square-face bicapped' | 'trigonal prismatic triangular-face bicapped' | 'trigonal prismatic with vacancy' | 'trigonal pyramidal': This data item translates the geometry output from a software program (for example, FindGeo or MetalCoord) into a unified naming scheme. As software programs sometimes have different names for the same geometry (for instance, 'tetrahedral' and 'tetrahedron' correspond to the same geometry), this data item provides a name for the geometry that is consistent regardless of the provenance to enhance findability. The geometry derived from observed geometries in atomic coordinate files.
    - `number` integer: The coordination number of the target atom.
    - `provenance` 'Author' | 'FindGeo' | 'MetalCoord' | 'PDB', required: The provenance of the feature assigned to this atom.
  - `pdbx_chem_comp_audit` PdbxChemCompAudit[]
    - `action_type` 'Create component' | 'Initial release' | 'Modify PCM' | 'Modify aromatic_flag' | 'Modify atom id' | 'Modify backbone' | 'Modify charge' | 'Modify component atom id' | 'Modify component comp_id' | 'Modify coordinates' | 'Modify descriptor' | 'Modify formal charge' | 'Modify formula' | 'Modify identifier' | 'Modify internal type' | 'Modify leaving atom flag' | 'Modify linking type' | 'Modify metal description' | 'Modify model coordinates code' | 'Modify name' | 'Modify one letter code' | 'Modify parent residue' | 'Modify processing site' | 'Modify subcomponent list' | 'Modify synonyms' | 'Modify value order' | 'Obsolete component' | 'Other modification': The action associated with this audit record.
    - `comp_id` string: This data item is a pointer to _chem_comp.id in the CHEM_COMP category.
    - `date` string, date-time: The date associated with this audit record.
    - `details` string: Additional details decribing this change.
    - `ordinal` integer, required: This data item is an ordinal index for the PDBX_CHEM_COMP_AUDIT category.
  - `pdbx_chem_comp_descriptor` PdbxChemCompDescriptor[]
    - `comp_id` string, required: This data item is a pointer to _chem_comp.id in the CHEM_COMP category.
    - `descriptor` string: This data item contains the descriptor value for this component.
    - `program` string, required: This data item contains the name of the program or library used to compute the descriptor.
    - `program_version` string, required: This data item contains the version of the program or library used to compute the descriptor.
    - `type` 'InChI' | 'InChIKey' | 'InChI_CHARGE' | 'InChI_FIXEDH' | 'InChI_ISOTOPE' | 'InChI_MAIN' | 'InChI_MAIN_CONNECT' | 'InChI_MAIN_FORMULA' | 'InChI_MAIN_HATOM' | 'InChI_RECONNECT' | 'InChI_STEREO' | 'SMILES' | 'SMILES_CANNONICAL' | 'SMILES_CANONICAL', required: This data item contains the descriptor type.
  - `pdbx_chem_comp_feature` PdbxChemCompFeature[]
    - `comp_id` string, required: The component identifier for this feature.
    - `source` string, required: The information source for the component feature.
    - `type` 'CARBOHYDRATE ANOMER' | 'CARBOHYDRATE ISOMER' | 'CARBOHYDRATE PRIMARY CARBONYL GROUP' | 'CARBOHYDRATE RING', required: The component feature type.
    - `value` string, required: The component feature value.
  - `pdbx_chem_comp_identifier` PdbxChemCompIdentifier[]
    - `comp_id` string, required: This data item is a pointer to _chem_comp.id in the CHEM_COMP category.
    - `identifier` string: This data item contains the identifier value for this component.
    - `program` string, required: This data item contains the name of the program or library used to compute the identifier.
    - `program_version` string, required: This data item contains the version of the program or library used to compute the identifier.
    - `type` 'CAS REGISTRY NUMBER' | 'COMMON NAME' | 'CONDENSED IUPAC CARB SYMBOL' | 'CONDENSED IUPAC CARBOHYDRATE SYMBOL' | 'IUPAC CARB SYMBOL' | 'IUPAC CARBOHYDRATE SYMBOL' | 'MDL Identifier' | 'PUBCHEM Identifier' | 'SNFG CARB SYMBOL' | 'SNFG CARBOHYDRATE SYMBOL' | 'SYNONYM' | 'SYSTEMATIC NAME', required: This data item contains the identifier type.
  - `pdbx_chem_comp_pcm` PdbxChemCompPcm[]
    - `category` 'ADP-ribose' | 'Amino acid' | 'Biotin' | 'Carbohydrate' | 'Chromophore/chromophore-like' | 'Covalent chemical modification' | 'Crosslinker' | 'Flavin' | 'Heme/heme-like' | 'Lipid/lipid-like' | 'Metal coordination' | 'Named protein modification' | 'Non-standard residue' | 'Nucleotide monophosphate' | 'Terminal acetylation' | 'Terminal amidation': The category of protein modification.
    - `comp_id_linking_atom` string: The atom on the modification group that covalently links the modification to the residue that is being modified. This is only added when the protein modification is linked and so the amino acid group and the modification group are described by separate CCDs.
    - `modified_residue_id` string: Chemical component identifier for the amino acid residue that is being modified.
    - `modified_residue_id_linking_atom` string: The atom on the polypeptide residue group that covalently links the modification to the residue that is being modified. This is only added when the protein modification is linked and so the amino acid group and the modification group are described by separate CCDs.
    - `polypeptide_position` 'Any position' | 'C-terminal' | 'N-terminal': The position of the modification on the polypeptide.
    - `position` 'Amino-acid backbone' | 'Amino-acid side chain' | 'Amino-acid side chain and backbone': The position of the modification on the amino acid.
    - `rcsb_modified_residue_id` string[]: Chemical component identifier for the amino acid residue that is being modified.
    - `type` '(3-Aminopropyl)(5'-adenosyl)phosphono amidation' | '(3R)-3-Hydroxybutyrylation' | '12-Hydroxyfarnesylation' | '12-Oxomyristoylation' | '12R-Hydroxymyristoylation' | '14-Hydroxy-10,13-dioxo-7-heptadecenoic acid' | '2,3-Dicarboxypropylation' | '2-Aminoadipylation' | '2-Aminoethylphosphorylation' | '2-Cholinephosphorylation' | '2-Hydroxyisobutyrylation' | '2-Oxo-5,5-dimethylhexanoylation' | '2-Oxobutanoic acid' | '3-Oxoalanine' | '3-Phenyllactic acid' | '4-Phosphopantetheine' | 'ADP-ribosylation' | 'ADP-riboxanation' | 'AMPylation' | 'Acetamidation' | 'Acetamidomethylation' | 'Acetylation' | 'Alanylation' | 'Allysine' | 'Amination' | 'Arachidoylation' | 'Archaeol' | 'Arginylation' | 'Arsenylation' | 'Asparaginylation' | 'Aspartylation' | 'Bacillithiolation' | 'Benzoylation' | 'Benzylation' | 'Beta-amino acid' | 'Beta-hydroxybutyrylation' | 'Beta-lysylation' | 'Beta-mercaptoethanol' | 'Biotinylation' | 'Bromination' | 'Butyrylation' | 'C-Mannosylation' | 'CMPylation' | 'Carbamoylation' | 'Carboxyethylation' | 'Carboxylation' | 'Carboxymethylation' | 'Chlorination' | 'Cholesterylation' | 'Citrullination' | 'Crotonylation' | 'Cyanation' | 'Cysteinylation' | 'D-alanylation' | 'D-arginylation' | 'D-asparaginylation' | 'D-aspartylation' | 'D-cysteinylation' | 'D-glutaminylation' | 'D-glutamylation' | 'D-histidinylation' | 'D-isoleucylation' | 'D-lactate' | 'D-leucylation' | 'D-lysylation' | 'D-methionylation' | 'D-phenylalanylation' | 'D-prolylation' | 'D-serylation' | 'D-threoninylation' | 'D-tryptophanylation' | 'D-tyrosination' | 'D-valylation' | 'Deamidation' | 'Decanoylation' | 'Decarboxylation' | 'Dehydroamino acid' | 'Dehydrocoelenterazination' | 'Dehydrogenation' | 'Dehydroxylation' | 'Deoxidation' | 'Deoxyhypusine' | 'Diacylglycerol' | 'Dihydroxyacetonation' | 'Dimethylamination' | 'Diphosphorylation' | 'Diphthamide' | 'Dipyrromethane methylation' | 'Dopaminylation' | 'Ethylation' | 'Ethylsulfanylation' | 'Farnesylation' | 'Fluorination' | 'Formylation' | 'GMPylation' | 'Geranylgeranylation' | 'Glutaminylation' | 'Glutamylation' | 'Glutarylation' | 'Glutathionylation' | 'Glycerophosphorylation' | 'Glycerylphosphorylethanolamination' | 'Glycylation' | 'Heptanoylation' | 'Hexanoylation' | 'Histaminylation' | 'Histidinylation' | 'Hydrogenation' | 'Hydroperoxylation' | 'Hydroxyamination' | 'Hydroxyethylation' | 'Hydroxylation' | 'Hydroxymethylation' | 'Hydroxysulfanylation' | 'Hypusine' | 'Iodination' | 'Isobutyrylation' | 'Isoleucylation' | 'L-lactate' | 'Lactoylation' | 'Laurylation' | 'Leucylation' | 'Lipoylation' | 'Lysylation' | 'Malonylation' | 'Methacrylation' | 'Methionylation' | 'Methoxylation' | 'Methylamination' | 'Methylation' | 'Methylsulfanylation' | 'Methylsulfation' | 'Myristoylation' | 'N-Glycosylation' | 'N-methylcarbamoylation' | 'N-pyruvic acid 2-iminylation' | 'N6-benzoyllysine' | 'N6-isonicotinyllysine' | 'N6-methacryllysine' | 'Nitration' | 'Nitrosylation' | 'None' | 'Noradrenylation' | 'Norleucine' | 'Norvaline' | 'O-Glycosylation' | 'Octanoylation' | 'Oleoylation' | 'Ornithine' | 'Oxidation' | 'Palmitoleoylation' | 'Palmitoylation' | 'Pentadecanoylation' | 'Pentanoylation' | 'Phenylalanylation' | 'Phosphatidylethanolamine amidation' | 'Phosphoenolpyruvate' | 'Phosphorylation' | 'Prolylation' | 'Propionylation' | 'Pyridoxal phosphate' | 'Pyrrolidone carboxylic acid' | 'Pyruvic acid' | 'Retinoylation' | 'S-Glycosylation' | 'Selanylation' | 'Selenomethionine' | 'Serotonylation' | 'Serylation' | 'Stearoylation' | 'Stereoisomerisation' | 'Succinamide ring' | 'Succination' | 'Succinylation' | 'Sulfanylmethylation' | 'Sulfation' | 'Sulfhydration' | 'Tert-butylation' | 'Tert-butyloxycarbonylation' | 'Threoninylation' | 'Thyroxine' | 'Triiodothyronine' | 'Triphosphorylation' | 'Tryptophanylation' | 'Tyrosination' | 'UMPylation' | 'Valylation' | 'cGMPylation': The type of protein modification.
    - `uniprot_generic_ptm_accession` string: The UniProt PTM accession code that describes the group of PTMs of which this protein modification is a member.
    - `uniprot_specific_ptm_accession` string: The UniProt PTM accession code that is an exact match for the protein modification.
  - `pdbx_family_prd_audit` PdbxFamilyPrdAudit[]
    - `action_type` 'Add PRD' | 'Create family' | 'Initial release' | 'Modify annotation' | 'Modify citation' | 'Modify family classification' | 'Modify family name' | 'Modify feature' | 'Modify molecule details' | 'Modify related structures' | 'Modify sequence' | 'Modify synonyms' | 'Obsolete family' | 'Obsolete familyt' | 'Other modification' | 'Remove PRD', required: The action associated with this audit record.
    - `annotator` string: The initials of the annotator creating of modifying the family.
    - `date` string, date-time, required: The date associated with this audit record.
    - `details` string: Additional details decribing this change.
    - `family_prd_id` string, required: This data item is a pointer to _pdbx_reference_molecule_family.family_prd_id in the pdbx_reference_molecule category.
    - `processing_site` string: An identifier for the wwPDB site creating or modifying the family.
  - `pdbx_prd_audit` PdbxPrdAudit[]
    - `action_type` 'Create molecule' | 'Initial release' | 'Modify audit' | 'Modify class' | 'Modify linkage' | 'Modify molecule name' | 'Modify representation' | 'Modify sequence' | 'Modify taxonomy organism' | 'Modify type' | 'Obsolete molecule' | 'Other modification', required: The action associated with this audit record.
    - `annotator` string: The initials of the annotator creating of modifying the molecule.
    - `date` string, date-time, required: The date associated with this audit record.
    - `details` string: Additional details decribing this change.
    - `prd_id` string, required: This data item is a pointer to _pdbx_reference_molecule.prd_id in the pdbx_reference_molecule category.
    - `processing_site` 'BMRB' | 'PDBC' | 'PDBE' | 'PDBJ' | 'RCSB': An identifier for the wwPDB site creating or modifying the molecule.
  - `pdbx_reference_entity_list` PdbxReferenceEntityList[]
    - `component_id` integer, required: The component number of this entity within the molecule.
    - `details` string: Additional details about this entity.
    - `prd_id` string, required: The value of _pdbx_reference_entity_list.prd_id is a reference _pdbx_reference_molecule.prd_id in the PDBX_REFERENCE_MOLECULE category.
    - `ref_entity_id` string, required: The value of _pdbx_reference_entity_list.ref_entity_id is a unique identifier the a constituent entity within this reference molecule.
    - `type` 'branched' | 'non-polymer' | 'polymer' | 'polymer-like': Defines the polymer characteristic of the entity.
  - `pdbx_reference_entity_poly` PdbxReferenceEntityPoly[]
    - `db_code` string: The database code for this source information
    - `db_name` string: The database name for this source information
    - `prd_id` string, required: The value of _pdbx_reference_entity_poly.prd_id is a reference _pdbx_reference_entity_list.prd_id in the PDBX_REFERENCE_ENTITY_LIST category.
    - `ref_entity_id` string, required: The value of _pdbx_reference_entity_poly.ref_entity_id is a reference to _pdbx_reference_entity_list.ref_entity_id in PDBX_REFERENCE_ENTITY_LIST category.
    - `type` 'nucleic-acid-like' | 'oligosaccharide' | 'peptide-like' | 'polysaccharide-like': The type of the polymer.
  - `pdbx_reference_entity_poly_link` PdbxReferenceEntityPolyLink[]
    - `atom_id_1` string: The atom identifier/name in the first of the two components making the linkage.
    - `atom_id_2` string: The atom identifier/name in the second of the two components making the linkage.
    - `comp_id_1` string: The component identifier in the first of the two components making the linkage. This data item is a pointer to _pdbx_reference_entity_poly_seq.mon_id in the PDBX_REFERENCE_ENTITY_POLY_SEQ category.
    - `comp_id_2` string: The component identifier in the second of the two components making the linkage. This data item is a pointer to _pdbx_reference_entity_poly_seq.mon_id in the PDBX_REFERENCE_ENTITY_POLY_SEQ category.
    - `component_id` integer, required: The entity component identifier entity containing the linkage.
    - `entity_seq_num_1` integer: For a polymer entity, the sequence number in the first of the two components making the linkage. This data item is a pointer to _pdbx_reference_entity_poly_seq.num in the PDBX_REFERENCE_ENTITY_POLY_SEQ category.
    - `entity_seq_num_2` integer: For a polymer entity, the sequence number in the second of the two components making the linkage. This data item is a pointer to _pdbx_reference_entity_poly_seq.num in the PDBX_REFERENCE_ENTITY_POLY_SEQ category.
    - `link_id` integer, required: The value of _pdbx_reference_entity_poly_link.link_id uniquely identifies a linkage within a polymer entity.
    - `prd_id` string, required: The value of _pdbx_reference_entity_poly_link.prd_id is a reference _pdbx_reference_entity_list.prd_id in the PDBX_REFERENCE_ENTITY_POLY category.
    - `ref_entity_id` string, required: The reference entity id of the polymer entity containing the linkage. This data item is a pointer to _pdbx_reference_entity_poly.ref_entity_id in the PDBX_REFERENCE_ENTITY_POLY category.
    - `value_order` 'arom' | 'delo' | 'doub' | 'pi' | 'poly' | 'quad' | 'sing' | 'trip': The bond order target for the non-standard linkage.
  - `pdbx_reference_entity_poly_seq` PdbxReferenceEntityPolySeq[]
    - `hetero` 'N' | 'Y', required: A flag to indicate that sequence heterogeneity at this monomer position.
    - `mon_id` string, required: This data item is the chemical component identifier of monomer.
    - `num` integer, required: The value of _pdbx_reference_entity_poly_seq.num must uniquely and sequentially identify a record in the PDBX_REFERENCE_ENTITY_POLY_SEQ list. This value is conforms to author numbering conventions and does not map directly to the numbering conventions used for _entity_poly_seq.num.
    - `observed` 'N' | 'Y': A flag to indicate that this monomer is observed in the instance example.
    - `parent_mon_id` string: This data item is the chemical component identifier for the parent component corresponding to this monomer.
    - `prd_id` string, required: The value of _pdbx_reference_entity_poly_seq.prd_id is a reference _pdbx_reference_entity_poly.prd_id in the PDBX_REFERENCE_ENTITY_POLY category.
    - `ref_entity_id` string, required: The value of _pdbx_reference_entity_poly_seq.ref_entity_id is a reference to _pdbx_reference_entity_poly.ref_entity_id in PDBX_REFERENCE_ENTITY_POLY category.
  - `pdbx_reference_entity_sequence` PdbxReferenceEntitySequence[]
    - `NRP_flag` 'N' | 'Y': A flag to indicate a non-ribosomal entity.
    - `one_letter_codes` string: The one-letter-code sequence for this entity. Non-standard monomers are represented as 'X'.
    - `prd_id` string, required: The value of _pdbx_reference_entity_sequence.prd_id is a reference _pdbx_reference_entity_list.prd_id in the PDBX_REFERENCE_ENTITY_LIST category.
    - `ref_entity_id` string, required: The value of _pdbx_reference_entity_sequence.ref_entity_id is a reference to _pdbx_reference_entity_list.ref_entity_id in PDBX_REFERENCE_ENTITY_LIST category.
    - `type` 'peptide-like' | 'saccharide': The monomer type for the sequence.
  - `pdbx_reference_entity_src_nat` PdbxReferenceEntitySrcNat[]
    - `atcc` string: The Americal Tissue Culture Collection code for organism from which the entity was isolated.
    - `db_code` string: The database code for this source information
    - `db_name` string: The database name for this source information
    - `ordinal` integer, required: The value of _pdbx_reference_entity_src_nat.ordinal distinguishes source details for this entity.
    - `organism_scientific` string: The scientific name of the organism from which the entity was isolated.
    - `prd_id` string, required: The value of _pdbx_reference_entity_src_nat.prd_id is a reference _pdbx_reference_entity_list.prd_id in the PDBX_REFERENCE_ENTITY_LIST category.
    - `ref_entity_id` string, required: The value of _pdbx_reference_entity_src_nat.ref_entity_id is a reference to _pdbx_reference_entity_list.ref_entity_id in PDBX_REFERENCE_ENTITY_LIST category.
    - `source` string: The data source for this information.
    - `source_id` string: A identifier within the data source for this information.
    - `taxid` string: The NCBI TaxId of the organism from which the entity was isolated.
  - `pdbx_reference_molecule` PdbxReferenceMolecule
    - `chem_comp_id` string: For entities represented as single molecules, the identifier corresponding to the chemical definition for the molecule.
    - `class` 'Antagonist' | 'Anthelmintic' | 'Antibiotic' | 'Antibiotic, Anthelmintic' | 'Antibiotic, Antimicrobial' | 'Antibiotic, Antineoplastic' | 'Anticancer' | 'Anticoagulant' | 'Anticoagulant, Antithrombotic' | 'Antifungal' | 'Antigen' | 'Antiinflammatory' | 'Antimicrobial' | 'Antimicrobial, Antiparasitic, Antibiotic' | 'Antimicrobial, Antiretroviral' | 'Antimicrobial, Antitumor' | 'Antineoplastic' | 'Antiparasitic' | 'Antiretroviral' | 'Antithrombotic' | 'Antitumor' | 'Antiviral' | 'CASPASE inhibitor' | 'Chaperone binding' | 'Drug delivery' | 'Enzyme inhibitor' | 'Glycan component' | 'Growth factor' | 'Immunosuppressant' | 'Inducer' | 'Inhibitor' | 'Lantibiotic' | 'Metabolism' | 'Metal transport' | 'Nutrient' | 'Oxidation-reduction' | 'Protein binding' | 'Receptor' | 'Substrate analog' | 'Synthetic opioid' | 'Thrombin inhibitor' | 'Thrombin inhibitor, Trypsin inhibitor' | 'Toxin' | 'Transition state mimetic' | 'Transport activator' | 'Trypsin inhibitor' | 'Unknown' | 'Water retention': Broadly defines the function of the entity.
    - `class_evidence_code` string: Evidence for the assignment of _pdbx_reference_molecule.class
    - `compound_details` string: Special details about this molecule.
    - `description` string: Description of this molecule.
    - `formula` string: The formula for the reference entity. Formulae are written according to the rules: 1. Only recognised element symbols may be used. 2. Each element symbol is followed by a 'count' number. A count of '1' may be omitted. 3. A space or parenthesis must separate each element symbol and its count, but in general parentheses are not used. 4. The order of elements depends on whether or not carbon is present. If carbon is present, the order should be: C, then H, then the other elements in alphabetical order of their symbol. If carbon is not present, the elements are listed purely in alphabetic order of their symbol. This is the 'Hill' system used by Chemical Abstracts.
    - `formula_weight` number, double: Formula mass in daltons of the entity.
    - `name` string: A name of the entity.
    - `prd_id` string, required: The value of _pdbx_reference_molecule.prd_id is the unique identifier for the reference molecule in this family. By convention this ID uniquely identifies the reference molecule in in the PDB reference dictionary. The ID has the template form PRD_dddddd (e.g. PRD_000001)
    - `release_status` 'HOLD' | 'OBS' | 'REL' | 'WAIT': Defines the current PDB release status for this molecule definition.
    - `replaced_by` string: Assigns the identifier of the reference molecule that has replaced this molecule.
    - `replaces` string: Assigns the identifier for the reference molecule which have been replaced by this reference molecule. Multiple molecule identifier codes should be separated by commas.
    - `represent_as` 'branched' | 'polymer' | 'single molecule': Defines how this entity is represented in PDB data files.
    - `representative_PDB_id_code` string: The PDB accession code for the entry containing a representative example of this molecule.
    - `type` 'Amino acid' | 'Aminoglycoside' | 'Ansamycin' | 'Anthracycline' | 'Anthraquinone' | 'Chalkophore' | 'Chalkophore, Polypeptide' | 'Chromophore' | 'Cyclic depsipeptide' | 'Cyclic lipopeptide' | 'Cyclic peptide' | 'Glycopeptide' | 'Heterocyclic' | 'Imino sugar' | 'Keto acid' | 'Lipoglycopeptide' | 'Lipopeptide' | 'Macrolide' | 'Non-polymer' | 'Nucleoside' | 'Oligopeptide' | 'Oligosaccharide' | 'Peptaibol' | 'Peptide-like' | 'Polycyclic' | 'Polypeptide' | 'Polysaccharide' | 'Quinolone' | 'Siderophore' | 'Thiolactone' | 'Thiopeptide' | 'Unknown': Defines the structural classification of the entity.
    - `type_evidence_code` string: Evidence for the assignment of _pdbx_reference_molecule.type
  - `pdbx_reference_molecule_annotation` PdbxReferenceMoleculeAnnotation[]
    - `family_prd_id` string, required: The value of _pdbx_reference_molecule_annotation.family_prd_id is a reference to _pdbx_reference_molecule_list.family_prd_id in category PDBX_REFERENCE_MOLECULE_FAMILY_LIST.
    - `ordinal` integer, required: This data item distinguishes anotations for this entity.
    - `prd_id` string: This data item is a pointer to _pdbx_reference_molecule.prd_id in the PDB_REFERENCE_MOLECULE category.
    - `source` string: The source of the annoation for this entity.
    - `text` string: Text describing the annotation for this entity.
    - `type` string: Type of annotation for this entity.
  - `pdbx_reference_molecule_details` PdbxReferenceMoleculeDetails[]
    - `family_prd_id` string, required: The value of _pdbx_reference_molecule_details.family_prd_id is a reference to _pdbx_reference_molecule_list.family_prd_id' in category PDBX_REFERENCE_MOLECULE_FAMILY.
    - `ordinal` integer, required: The value of _pdbx_reference_molecule_details.ordinal is an ordinal that distinguishes each descriptive text for this entity.
    - `source` string: A data source of this information (e.g. PubMed, Merck Index)
    - `source_id` string: A identifier within the data source for this information.
    - `text` string: The text of the description of special aspects of the entity.
  - `pdbx_reference_molecule_family` PdbxReferenceMoleculeFamily
    - `family_prd_id` string, required: The value of _pdbx_reference_entity.family_prd_id must uniquely identify a record in the PDBX_REFERENCE_MOLECULE_FAMILY list. By convention this ID uniquely identifies the reference family in in the PDB reference dictionary. The ID has the template form FAM_dddddd (e.g. FAM_000001)
    - `name` string: The entity family name.
    - `release_status` 'HOLD' | 'OBS' | 'REL' | 'WAIT': Assigns the current PDB release status for this family.
    - `replaced_by` string: Assigns the identifier of the family that has replaced this component.
    - `replaces` string: Assigns the identifier for the family which have been replaced by this family. Multiple family identifier codes should be separated by commas.
  - `pdbx_reference_molecule_features` PdbxReferenceMoleculeFeatures[]
    - `family_prd_id` string, required: The value of _pdbx_reference_molecule_features.family_prd_id is a reference to _pdbx_reference_molecule_list.family_prd_id in category PDBX_REFERENCE_MOLECULE_FAMILY_LIST.
    - `ordinal` integer, required: The value of _pdbx_reference_molecule_features.ordinal distinguishes each feature for this entity.
    - `prd_id` string, required: The value of _pdbx_reference_molecule_features.prd_id is a reference _pdbx_reference_molecule.prd_id in the PDBX_REFERENCE_MOLECULE category.
    - `source` string: The information source for the component feature.
    - `source_ordinal` integer: The value of _pdbx_reference_molecule_features.source_ordinal provides the priority order of features from a particular source or database.
    - `type` string: The entity feature type.
    - `value` string: The entity feature value.
  - `pdbx_reference_molecule_list` PdbxReferenceMoleculeList[]
    - `family_prd_id` string, required: The value of _pdbx_reference_molecule_list.family_prd_id is a reference to _pdbx_reference_molecule_family.family_prd_id' in category PDBX_REFERENCE_MOLECULE_FAMILY.
    - `prd_id` string, required: The value of _pdbx_reference_molecule_list.prd_id is the unique identifier for the reference molecule in this family. By convention this ID uniquely identifies the reference molecule in in the PDB reference dictionary. The ID has the template form PRD_dddddd (e.g. PRD_000001)
  - `pdbx_reference_molecule_related_structures` PdbxReferenceMoleculeRelatedStructures[]
    - `citation_id` string: A link to related reference information in the citation category.
    - `db_accession` string: The database accession code for the related structure reference.
    - `db_code` string: The database identifier code for the related structure reference.
    - `db_name` string: The database name for the related structure reference.
    - `family_prd_id` string, required: The value of _pdbx_reference_molecule_related_structures.family_prd_id is a reference to _pdbx_reference_molecule_list.family_prd_id in category PDBX_REFERENCE_MOLECULE_FAMILY_LIST.
    - `formula` string: The formula for the reference entity. Formulae are written according to the rules: 1. Only recognised element symbols may be used. 2. Each element symbol is followed by a 'count' number. A count of '1' may be omitted. 3. A space or parenthesis must separate each element symbol and its count, but in general parentheses are not used. 4. The order of elements depends on whether or not carbon is present. If carbon is present, the order should be: C, then H, then the other elements in alphabetical order of their symbol. If carbon is not present, the elements are listed purely in alphabetic order of their symbol. This is the 'Hill' system used by Chemical Abstracts.
    - `name` string: The chemical name for the structure entry in the related database
    - `ordinal` integer, required: The value of _pdbx_reference_molecule_related_structures.ordinal distinguishes related structural data for each entity.
  - `pdbx_reference_molecule_synonyms` PdbxReferenceMoleculeSynonyms[]
    - `family_prd_id` string, required: The value of _pdbx_reference_molecule_synonyms.family_prd_id is a reference to _pdbx_reference_molecule_list.family_prd_id in category PDBX_REFERENCE_MOLECULE_FAMILY_LIST.
    - `name` string: A synonym name for the entity.
    - `ordinal` integer, required: The value of _pdbx_reference_molecule_synonyms.ordinal is an ordinal to distinguish synonyms for this entity.
    - `prd_id` string, required: The value of _pdbx_reference_molecule_synonyms.prd_id is a reference _pdbx_reference_molecule.prd_id in the PDBX_REFERENCE_MOLECULE category.
    - `source` string: The source of this synonym name for the entity.
  - `rcsb_bird_citation` RcsbBirdCitation[]
    - `id` string, required: The value of _rcsb_bird_citation.id must uniquely identify a record in the rcsb_bird_citation list.
    - `journal_abbrev` string: Abbreviated name of the cited journal as given in the Chemical Abstracts Service Source Index.
    - `journal_volume` string: Volume number of the journal cited; relevant for journal articles.
    - `page_first` string: The first page of the rcsb_bird_citation; relevant for journal articles, books and book chapters.
    - `page_last` string: The last page of the rcsb_bird_citation; relevant for journal articles, books and book chapters.
    - `pdbx_database_id_DOI` string: Document Object Identifier used by doi.org to uniquely specify bibliographic entry.
    - `pdbx_database_id_PubMed` integer: Ascession number used by PubMed to categorize a specific bibliographic entry.
    - `rcsb_authors` string[]: Names of the authors of the citation; relevant for journal articles, books and book chapters. Names are separated by vertical bars. The family name(s), followed by a comma and including any dynastic components, precedes the first name(s) or initial(s).
    - `title` string: The title of the rcsb_bird_citation; relevant for journal articles, books and book chapters.
    - `year` integer: The year of the rcsb_bird_citation; relevant for journal articles, books and book chapters.
  - `rcsb_chem_comp_annotation` RcsbChemCompAnnotation[]
    - `annotation_id` string: An identifier for the annotation.
    - `assignment_version` string: Identifies the version of the annotation assignment.
    - `description` string: A description for the annotation.
    - `name` string: A name for the annotation.
    - `provenance_source` string: Code identifying the individual, organization or program that assigned the annotation.
    - `type` 'ATC' | 'Carbohydrate Anomer' | 'Carbohydrate Isomer' | 'Carbohydrate Primary Carbonyl Group' | 'Carbohydrate Ring' | 'Generating Enzyme' | 'Modification Type' | 'PSI-MOD': A type or category of the annotation.
    - `annotation_lineage` RcsbChemCompAnnotationAnnotationLineage[]
      - `depth` integer: Members of the annotation lineage as parent lineage depth (1-N)
      - `id` string: Members of the annotation lineage as parent class identifiers.
      - `name` string: Members of the annotation lineage as parent class names.
  - `rcsb_chem_comp_container_identifiers` RcsbChemCompContainerIdentifiers
    - `atc_codes` string[]: The Anatomical Therapeutic Chemical (ATC) Classification System identifiers corresponding to the chemical component.
    - `comp_id` string, required: The chemical component identifier.
    - `drugbank_id` string: The DrugBank identifier corresponding to the chemical component.
    - `prd_id` string: The BIRD definition identifier.
    - `rcsb_id` string: A unique identifier for the chemical definition in this container.
    - `subcomponent_ids` string[]: The list of subcomponents contained in this component.
  - `rcsb_chem_comp_descriptor` RcsbChemCompDescriptor
    - `InChI` string: Standard IUPAC International Chemical Identifier (InChI) descriptor for the chemical component. InChI, the IUPAC International Chemical Identifier, by Stephen R Heller, Alan McNaught, Igor Pletnev, Stephen Stein and Dmitrii Tchekhovskoi, Journal of Cheminformatics, 2015, 7:23;
    - `InChIKey` string: Standard IUPAC International Chemical Identifier (InChI) descriptor key for the chemical component InChI, the IUPAC International Chemical Identifier, by Stephen R Heller, Alan McNaught, Igor Pletnev, Stephen Stein and Dmitrii Tchekhovskoi, Journal of Cheminformatics, 2015, 7:23
    - `SMILES` string: Simplified molecular-input line-entry system (SMILES) descriptor for the chemical component. Weininger D (February 1988). "SMILES, a chemical language and information system. 1. Introduction to methodology and encoding rules". Journal of Chemical Information and Modeling. 28 (1): 31-6. Weininger D, Weininger A, Weininger JL (May 1989). "SMILES. 2. Algorithm for generation of unique SMILES notation", Journal of Chemical Information and Modeling. 29 (2): 97-101.
    - `SMILES_stereo` string: Simplified molecular-input line-entry system (SMILES) descriptor for the chemical component including stereochemical features. Weininger D (February 1988). "SMILES, a chemical language and information system. 1. Introduction to methodology and encoding rules". Journal of Chemical Information and Modeling. 28 (1): 31-6. Weininger D, Weininger A, Weininger JL (May 1989). "SMILES. 2. Algorithm for generation of unique SMILES notation". Journal of Chemical Information and Modeling. 29 (2): 97-101.
    - `comp_id` string, required: The chemical component identifier.
  - `rcsb_chem_comp_info` RcsbChemCompInfo
    - `atom_count` integer: Chemical component total atom count
    - `atom_count_chiral` integer: Chemical component chiral atom count
    - `atom_count_heavy` integer: Chemical component heavy atom count
    - `bond_count` integer: Chemical component total bond count
    - `bond_count_aromatic` integer: Chemical component aromatic bond count
    - `comp_id` string, required: The chemical component identifier.
    - `initial_deposition_date` string, date-time: The date the chemical definition was first deposited in the PDB repository.
    - `initial_release_date` string, date-time: The initial date the chemical definition was released in the PDB repository.
    - `release_status` 'DEL' | 'HOLD' | 'HPUB' | 'OBS' | 'REF_ONLY' | 'REL': The release status of the chemical definition.
    - `revision_date` string, date-time: The date of last revision of the chemical definition.
  - `rcsb_chem_comp_related` RcsbChemCompRelated[]
    - `comp_id` string, required: The value of _rcsb_chem_comp_related.comp_id is a reference to a chemical component definition.
    - `ordinal` integer, required: The value of _rcsb_chem_comp_related.ordinal distinguishes related examples for each chemical component.
    - `related_mapping_method` 'assigned by DrugBank resource' | 'assigned by PDB' | 'assigned by PubChem resource' | 'matching ChEMBL ID in Pharos' | 'matching InChIKey in DrugBank' | 'matching InChIKey in PubChem' | 'matching InChIKey-prefix in DrugBank' | 'matching by RESID resource': The method used to establish the resource correspondence.
    - `resource_accession_code` string: The resource identifier code for the related chemical reference.
    - `resource_name` 'CAS' | 'CCDC/CSD' | 'COD' | 'ChEBI' | 'ChEMBL' | 'DrugBank' | 'Pharos' | 'PubChem' | 'RESID': The resource name for the related chemical reference.
  - `rcsb_chem_comp_synonyms` RcsbChemCompSynonyms[]
    - `comp_id` string, required: The chemical component to which this synonym applies.
    - `name` string: The synonym of this particular chemical component.
    - `ordinal` integer, required: This data item is an ordinal index for the RCSB_CHEM_COMP_SYNONYMS category.
    - `provenance_source` 'ACDLabs' | 'Author' | 'ChEBI' | 'ChEMBL' | 'DrugBank' | 'GMML' | 'Lexichem' | 'OpenEye OEToolkits' | 'OpenEye/Lexichem' | 'PDB Reference Data' | 'PDB Reference Data (Preferred)' | 'PDB-CARE' | 'PubChem' | 'RESID': The provenance of this synonym.
    - `type` 'Brand Name' | 'Common Name' | 'Condensed IUPAC Carbohydrate Symbol' | 'IUPAC Carbohydrate Symbol' | 'Preferred Common Name' | 'Preferred Name' | 'Preferred Synonym' | 'SNFG Carbohydrate Symbol' | 'Synonym' | 'Systematic Name': This data item contains the synonym type.
  - `rcsb_chem_comp_target` RcsbChemCompTarget[]
    - `comp_id` string, required: The value of _rcsb_chem_comp_target.comp_id is a reference to a chemical component definition.
    - `interaction_type` string: The type of target interaction.
    - `name` string: The chemical component target name.
    - `ordinal` integer, required: The value of _rcsb_chem_comp_target.ordinal distinguishes related examples for each chemical component.
    - `provenance_source` 'DrugBank' | 'PDB Primary Data': A code indicating the provenance of the target interaction assignment
    - `reference_database_accession_code` string: The reference identifier code for the target interaction reference.
    - `reference_database_name` 'UniProt': The reference database name for the target interaction.
    - `target_actions` string[]: The mechanism of action of the chemical component - target interaction.
  - `rcsb_schema_container_identifiers` RcsbSchemaContainerIdentifiers[]
    - `collection_name` string, required: Collection name associated with the data in the container.
    - `collection_schema_version` string: Version string for the schema and collection.
    - `schema_name` string, required: Schema name associated with the data in the container.
  - `rcsb_id` string, required: A unique identifier for the chemical definition in this container.

## Other responses

- `404`: Not Found

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