6H2C:
reference: New Conformations of Acylation Adducts of Inhibitors of beta-Lactamase from Mycobacterium tuberculosis., Tassoni R, Blok A, Pannu NS, Ubbink M, Biochemistry. 2019 Feb 19;58(7):997-1009. doi: 10.1021/acs.biochem.8b01085. Epub , 2019 Jan 30. PMID: 30632739

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