4PTZ:
reference: Crystal Structure of Escherichia coli SsuE: Defining a General Catalytic Cycle for FMN Reductases of the Flavodoxin-like Superfamily., Driggers CM, Dayal PV, Ellis HR, Karplus PA, Biochemistry. 2014 Jun 3;53(21):3509-19. doi: 10.1021/bi500314f. Epub 2014 May, 21. PMID: 24816272

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