Answers.Body: <p>I'm not sure about the RCSB, but you can get such a list from the PDBe REST API, as documented in the <a href="http://www.ebi.ac.uk/pdbe/api/doc/compounds.html" rel="nofollow noreferrer">compounds section</a>:</p>
  
  <p><a href="http://www.ebi.ac.uk/pdbe/api/pdb/compound/in_pdb/ADN" rel="nofollow noreferrer">http://www.ebi.ac.uk/pdbe/api/pdb/compound/in_pdb/ADN</a></p>
  
  <p>Alternatively, from an older service:</p>
  
  <p><a href="http://www.ebi.ac.uk/pdbe-srv/pdbechem/PDBEntry/download/ADN" rel="nofollow noreferrer">http://www.ebi.ac.uk/pdbe-srv/pdbechem/PDBEntry/download/ADN</a></p>
  
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Answers.CreationDate: 2018-06-14T16:30:33.723Z
Answers.LastActivityDate: 2018-06-14T16:30:33.723Z
Answers.UserDisplayName: marcin
Body: <p>If you're looking at the entry for a ligand, for example, <a href="http://www.rcsb.org/ligand/ADN" rel="nofollow noreferrer">adenosine</a>, there's a link on the webpage to entries for which this entry exists as a free ligand. 
  However, I want to access this via the API and can't seem to find docs/info on how to do that. </p>
  
  <p>I have been looking at the fields you can use to get <a href="https://www.rcsb.org/pdb/results/reportField.do" rel="nofollow noreferrer">custom reports</a>.  </p>
  
Tags: <pdb>
Title: Can you query the RCSB PDB API with a ligand and return the IDs of all entries in which it appears as a free ligand?
ThreadText: # Can you query the RCSB PDB API with a ligand and return the IDs of all entries in which it appears as a free ligand?
  
  (Asked by: username_0 on 2018-06-14)
  
  If you're looking at the entry for a ligand, for example, [adenosine](http://www.rcsb.org/ligand/ADN), there's a link on the webpage to entries for which this entry exists as a free ligand.
  However, I want to access this via the API and can't seem to find docs/info on how to do that.
  
  I have been looking at the fields you can use to get [custom reports](https://www.rcsb.org/pdb/results/reportField.do).
  
  **Tags:** pdb
  
  
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  ## 1 answers
  
  ### Answer by username_1 on 2018-06-14. Score: 2
  
  I'm not sure about the RCSB, but you can get such a list from the PDBe REST API, as documented in the [compounds section](http://www.ebi.ac.uk/pdbe/api/doc/compounds.html):
  
  <http://www.ebi.ac.uk/pdbe/api/pdb/compound/in_pdb/ADN>
  
  Alternatively, from an older service:
  
  <http://www.ebi.ac.uk/pdbe-srv/pdbechem/PDBEntry/download/ADN>
  
  
  ---
  
  