6AUH:
reference: Artificial Metalloproteins Containing Co4O4 Cubane Active Sites., Olshansky L, Huerta-Lavorie R, Nguyen AI, Vallapurackal J, Furst A, Tilley TD, Borovik AS, J Am Chem Soc. 2018 Feb 13. doi: 10.1021/jacs.7b13052. PMID: 29401385

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