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Chemical Components

The geometrical and stereochemical description of the models used to refine a structure are specified in the categories in the CHEM_COMP group. This group of categories include the covalent geometry, stereochemistry, and model cartesian coordinates for chemical components. Chemical components may be monomers within a polymer entity or non-polymer entities. Each component is labeled with an component identifier (_comp.id) which appears at many levels in the description of structure and structural features (e.g. _atom_site.label_comp_id, _entity_poly_seq.mon_id, or _struct_conf.beg_label_comp_id). The categories which describe chemical components are shown in the following diagram.

An abbreviated example of a component description for a non-polymer ligand component.


###############
## CHEM_COMP ##
###############

_chem_comp.id                'DM2'
_chem_comp.name              'ADRIAMYCIN'
_chem_comp.type               non-polymer
_chem_comp.ndb_synonyms      'ADRIAMYCIN'
_chem_comp.formula           'C27 H29 N1 O11'
_chem_comp.number_atoms_all  68
_chem_comp.number_atoms_nh   39
_chem_comp.formula_weight    543.51

####################
## CHEM_COMP_ATOM ##
####################

loop_
_chem_comp_atom.comp_id
_chem_comp_atom.atom_id
_chem_comp_atom.type_symbol
_chem_comp_atom.model_cartn_x
_chem_comp_atom.model_cartn_y
_chem_comp_atom.model_cartn_z
DM2 'C1'  C  12.996  0.476  12.694
DM2 'C2'  C  13.982 -0.225  13.183  
DM2 'C3'  C  12.482  0.165  11.515  
# ....... Abbreviated   ...........

####################
## CHEM_COMP_BOND ##
####################

loop_
_chem_comp_bond.comp_id
_chem_comp_bond.atom_id_1
_chem_comp_bond.atom_id_2
_chem_comp_bond.value_order
_chem_comp_bond.value_dist
_chem_comp_bond.value_dist_esd
 DM2 'C1' 'C2' sing  1.517  0.0210 
 DM2 'C2' 'C3' sing  1.445  0.0040 
# ....... Abbreviated   ...........
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