3K30:
reference: Crystal structure of histamine dehydrogenase from Nocardioides simplex., Reed T, Lushington GH, Xia Y, Hirakawa H, Travis DM, Mure M, Scott EE, Limburg J, J Biol Chem. 2010 Aug 13;285(33):25782-91. Epub 2010 Jun 10. PMID: 20538584

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