D-octopine dehydrogenase

Octopine dehydrogenase (N2-(D-1-carboxyethyl)-L-arginine:NAD+ oxidoreductase, OcDH, ODH) is a dehydrogenase enzyme in the opine dehydrogenase family that helps maintain redox balance under anaerobic conditions. It is found largely in aquatic invertebrates, especially mollusks, sipunculids, and coelenterates, and plays a role analogous to lactate dehydrogenase (found largely in vertebrates) . In the presence of NADH, OcDH catalyzes the reductive condensation of an α-keto acid with an amino acid to form N-carboxyalkyl-amino acids (opines). The purpose of this reaction is to reoxidize glycolytically formed NADH to NAD+, replenishing this important reductant used in glycolysis and allowing for the continued production of ATP in the absence of oxygen.

L-arginine + pyruvate + NADH + H⁺ ${\displaystyle \rightleftharpoons }$ D-octopine + NAD⁺ + H₂O