Opine dehydrogenase () is an enzyme that catalyzes several chemical reactions involving a class of molecules called opines. An example is:
The three substrates of this enzyme are an opine such as (2S)-2-[(R)-1-carboxyethylamino]pentanoic acid (1), oxidised nicotinamide adenine dinucleotide (NAD<sup>+</sup>), and water. When acting in the forward direction, the products in this example are L-norvaline, reduced NADH, pyruvic acid and a proton.
The enzyme can also catalyse reactions that make opines by adding a molecule of pyruvic acid or other keto acids to L-amino acids. This includes making derivatives of L-methionine, L-isoleucine, L-valine, and L-phenylalanine.