2BZ1:
reference: GTP cyclohydrolase II structure and mechanism., Ren J, Kotaka M, Lockyer M, Lamb HK, Hawkins AR, Stammers DK, J Biol Chem. 2005 Nov 4;280(44):36912-9. Epub 2005 Aug 22. PMID: 16115872

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