4FFR:
reference: Biosynthesis of the 22nd genetically encoded amino acid pyrrolysine: structure and reaction mechanism of PylC at 1.5A resolution., Quitterer F, List A, Beck P, Bacher A, Groll M, J Mol Biol. 2012 Dec 14;424(5):270-82. doi: 10.1016/j.jmb.2012.09.007. Epub 2012 , Sep 14. PMID: 22985965

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