1VFS:
reference: Structural evidence that alanine racemase from D-cycloserine-producing-microorganism exhibits resistance to its own product., Noda M, Matoba Y, Kumagai T, Sugiyama M, J Biol Chem 2004 Aug 9;. PMID: 15302886

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