1LOP:
reference: The substrate-binding site in Escherichia coli cyclophilin A preferably recognizes a cis-proline isomer or a highly distorted form of the trans isomer., Konno M, Ito M, Hayano T, Takahashi N, J Mol Biol 1996 Mar 15;256(5):897-908. PMID: 8601841

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).