4IPJ:
reference: Arg314 Is Essential for Catalysis by N-Acetyl Neuraminic Acid Synthase from Neisseria meningitidis., Joseph DD, Jiao W, Parker EJ, Biochemistry. 2013 Apr 5. PMID: 23534460

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