3CIW:
reference: X-ray Structure of the [FeFe]-Hydrogenase Maturase HydE from Thermotoga maritima., Nicolet Y, Rubach JK, Posewitz MC, Amara P, Mathevon C, Atta M, Fontecave M, Fontecilla-Camps JC, J Biol Chem. 2008 Jul 4;283(27):18861-18872. Epub 2008 Apr 8. PMID: 18400755

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