In enzymology, an opine dehydrogenase (EC 1.5.1.28) is an enzyme that catalyzes the chemical reaction

(2S)-2-{[1-(R)-carboxyethyl]amino}pentanoate + NAD⁺ + H₂O L-2-aminopentanoic acid + pyruvate + NADH + H⁺

The 3 substrates of this enzyme are [[(2S)-2-{[1-(R)-carboxyethyl]amino}pentanoate]], NAD⁺, and H₂O, whereas its 4 products are L-2-aminopentanoic acid, pyruvate, NADH, and H⁺.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is (2S)-2-{[1-(R)-carboxyethyl]amino}pentanoate:NAD+ oxidoreductase (L-aminopentanoate-forming). Other names in common use include (2S)-2-{[1-(R)-carboxyethyl]amino}pentanoate dehydrogenase (NAD+,, and L-aminopentanoate-forming).

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• Kato Y, Yamada H, Asano Y (1996). "Stereoselective synthesis of opine-type secondary amine carboxylic acids by a new enzyme opine dehydrogenase. Use of recombinant enzymes". J. Mol. Catal., B Enzym. 1 (3–6): 151–160. doi:10.1016/1381-1177(95)00011-9.