3IVA:
reference: Insights into the reactivation of cobalamin-dependent methionine synthase., Koutmos M, Datta S, Pattridge KA, Smith JL, Matthews RG, Proc Natl Acad Sci U S A. 2009 Nov 3;106(44):18527-32. Epub 2009 Oct 21. PMID: 19846791

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