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Sites

Binding sites and active sites are described by a collection of categories descending from category STRUCT_SITE. A textual description including keywords and a series of views can be specified for each site. Sites are generated from a list of structural features and associated symmetry transformations. Structural features forming a site are labeled using some combination of the identifiers used to label atomic positions in the ATOM_SITE category. These identifiers include the asymmetric unit identifier, component identifier, sequence position, and the atom name. This is illustrated in the following diagram.

An example that describes the two binding sites in the HIV protease system (PDB 5HVP, Fitzgerald et al., 1990).

loop_
_struct_site.id
_struct_site.details
  'P2 site C'
; residues with a contact < 3.7 Angstroms to an atom in the P2 moiety of the
  inhibitor in the conformation with _struct_asym.id = C
;
  'P2 site D'
; residues with a contact < 3.7 Angstroms to an atom in the P1 moiety of the
  inhibitor in the conformation with _struct_asym.id = D)
;
#
loop_
_struct_site_gen.id
_struct_site_gen.site_id
_struct_site_gen.label_comp_id
_struct_site_gen.label_asym_id
_struct_site_gen.label_seq_id
_struct_site_gen.symmetry
_struct_site_gen.details
 1  'P2 site C'  VAL  A   32  1_555  .
 2  'P2 site C'  ILE  A   47  1_555  .
 3  'P2 site C'  VAL  A   82  1_555  .
 4  'P2 site C'  ILE  A   84  1_555  .
 5  'P2 site D'  VAL  B  232  1_555  .
 6  'P2 site D'  ILE  B  247  1_555  .
 7  'P2 site D'  VAL  B  282  1_555  .
 8  'P2 site D'  ILE  B  284  1_555  .

An abbreviated example that describes the binding site for an intercalating drug in a drug-DNA complex (NDB DDF040, Leonard et al., 1993).

loop_                                                                   
_struct_site.id			  
_struct_site.details		  
B1 'Binding at TG/AC Step 1'	  
				  
loop_				  
_struct_site_keywords.site_id	  
_struct_site_keywords.text	  
B1  'Intercalation complex'       

loop_                             
_struct_site_gen.id               
_struct_site_gen.site_id          
_struct_site_gen.label_asym_id    
_struct_site_gen.label_comp_id    
_struct_site_gen.label_seq_id     
_struct_site_gen.symmetry         
  1 B1 A    T  1 1_555            
  2 B1 A    G  2 1_555            
  3 B1 A    C  5 8_555            
  4 B1 A    A  6 8_555            
  5 B1 D  DM2  . 8_555            
				  
loop_				  
_struct_site_view.id		  
_struct_site_view.site_id	  
_struct_site_view.details
_struct_site_view.rot_matrix[1][1] 
_struct_site_view.rot_matrix[1][2]
          ...
_struct_site_view.rot_matrix[3][3]
 View1  B1 
'View along the base-pair plane' 
 0.133  0.922  ... -0.172 

loop_
_atom_site.id
_atom_site.label_atom_id                  
_atom_site.label_comp_id                  
_atom_site.label_asym_id                  
_atom_site.auth_seq_id                   
_atom_site.cartn_x                        
_atom_site.cartn_y                        
_atom_site.cartn_z                        
_atom_site.occupancy                      
_atom_site.B_iso_or_equiv                 
_atom_site.label_entity_id
_atom_site.label_seq_id
   1  O5*   T A   1     -18.744  20.195  22.722  1.00 36.68  1  1         
  18  P     G A   2     -14.347  22.307  21.991  1.00 40.20  1  2
  81  P     C A   5      -3.756  13.529   9.644  1.00 31.11  1  5
 106  O4*   A A   6     -10.114   9.255   2.687  1.00 27.42  1  6
 122  C1  DM2 D   7     -12.358  18.750   5.310  1.00  2.93  2 .     
#                 ... Abbreviated ...
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