2AFR:
reference: The crystal structure of putative precorrin isomerase CbiC in cobalamin biosynthesis., Xue Y, Wei Z, Li X, Gong W, J Struct Biol. 2006 Mar;153(3):307-11. Epub 2005 Dec 27. PMID: 16427313

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