3VQR:
reference: Crystal Structure of Novel Dye-linked L-Proline Dehydrogenase from Hyperthermophilic Archaeon Aeropyrum pernix., Sakuraba H, Satomura T, Kawakami R, Kim K, Hara Y, Yoneda K, Ohshima T, J Biol Chem. 2012 Jun 8;287(24):20070-80. Epub 2012 Apr 16. PMID: 22511758

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