4ILQ:
reference: Chlamydia trachomatis CT771 (nudH) Is an Asymmetric Ap4A Hydrolase., Barta ML, Lovell S, Sinclair AN, Battaile KP, Hefty PS, Biochemistry. 2014 Jan 14;53(1):214-24. doi: 10.1021/bi401473e. Epub 2013 Dec 31. PMID: 24354275

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