4GMA:
reference: B12 cofactors directly stabilize an mRNA regulatory switch., Johnson JE Jr, Reyes FE, Polaski JT, Batey RT, Nature. 2012 Dec 6;492(7427):133-7. doi: 10.1038/nature11607. Epub 2012 Oct 14. PMID: 23064232

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