1JUW:
reference: An insight into the active site of a type I DNA topoisomerase from the kinetoplastid protozoan Leishmania donovani., Das A, Mandal C, Dasgupta A, Sengupta T, Majumder HK, Nucleic Acids Res 2002 Feb 1;30(3):794-802. PMID: 11809893

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