5BVH:
reference: Catalysis-dependent selenium incorporation and migration in the nitrogenase active site iron-molybdenum cofactor., Spatzal T, Perez KA, Howard JB, Rees DC, Elife. 2015 Dec 16;4. pii: e11620. doi: 10.7554/eLife.11620. PMID: 26673079

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