6FNR:
reference: Inhibition and Regulation of the Ergothioneine Biosynthetic Methyltransferase EgtD., Misson L, Burn R, Vit A, Hildesheim J, Beliaeva MA, Blankenfeldt W, Seebeck FP, ACS Chem Biol. 2018 May 18;13(5):1333-1342. doi: 10.1021/acschembio.8b00127. Epub, 2018 Apr 16. PMID: 29658702

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