5OEF:
reference: Chalcogenide substitution in the [2Fe] cluster of [FeFe]-hydrogenases conserves high enzymatic activity., Kertess L, Wittkamp F, Sommer C, Esselborn J, Rudiger O, Reijerse EJ, Hofmann E, Lubitz W, Winkler M, Happe T, Apfel UP, Dalton Trans. 2017 Nov 27. doi: 10.1039/c7dt03785f. PMID: 29177350

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