6VZ9:
reference: Covalent Modification of the Flavin in Proline Dehydrogenase by Thiazolidine-2-Carboxylate., Campbell AC, Becker DF, Gates KS, Tanner JJ, ACS Chem Biol. 2020 Mar 11. doi: 10.1021/acschembio.9b00935. PMID: 32159324

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