2SFP:
reference: Structure of a Michaelis complex analogue: propionate binds in the substrate carboxylate site of alanine racemase., Morollo AA, Petsko GA, Ringe D, Biochemistry 1999 Mar 16;38(11):3293-301. PMID: 10079072

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