4A5A:
reference: Structural insight into the activation mechanism of Toxoplasma gondii nucleoside triphosphate diphosphohydrolases by disulfide reduction., Krug U, Zebisch M, Krauss M, Strater N, J Biol Chem. 2011 Nov 30. PMID: 22130673

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