5TK9:
reference: An HD domain phosphohydrolase active site tailored for oxetanocin-A biosynthesis., Bridwell-Rabb J, Kang G, Zhong A, Liu HW, Drennan CL, Proc Natl Acad Sci U S A. 2016 Nov 29;113(48):13750-13755. Epub 2016 Nov 14. PMID: 27849620

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