2G1P:
reference: Structure and substrate recognition of the Escherichia coli DNA adenine methyltransferase., Horton JR, Liebert K, Bekes M, Jeltsch A, Cheng X, J Mol Biol. 2006 Apr 28;358(2):559-70. Epub 2006 Feb 28. PMID: 16524590

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