In the forward direction acts also on secondary amine dicarboxylates such as N-(1-carboxyethyl)methionine and N-(1-carboxyethyl)phenylalanine. In the reverse direction, the enzyme also acts on neutral amino acids as an amino donor. They include L-amino acids such as 2-aminopentanoic acid, 2-aminobutyric acid, 2-aminohexanoic acid, 3-chloroalanine, O-acetylserine, methionine, isoleucine, valine, phenylalanine, leucine and alanine. (2S)-2-[(R)-1-carboxyethylamino]pentanoate + H2O + NAD(+) = H(+) + L-2-aminopentanoate + NADH + pyruvate Homodimer. Belongs to the lysopine/nopaline/octopine/opine/vitopine dehydrogenases family.