Hydrogen-bond network in the O. oeni alanine racemase active site. Hydrogen bonds with an interaction distance of less than 3.0 Å are depicted by dotted lines. The active site is formed by both monomers. Residues Lys39, Tyr43, Ser203, Arg221, Gly223 and Thr224 from one monomer (in cyan) and Tyr266 from the opposing monomer (in green) are shown as stick models. PLP is shown as a stick model (salmon).