Catalyzes the NAD-dependent oxidation of 2-aminomuconic semialdehyde of the kynurenine metabolic pathway in L-tryptophan degradation. 2-aminomuconate 6-semialdehyde + H2O + NAD(+) = (2Z,4E)-2-aminomuconate + 2 H(+) + NADH Activity was measured with total soluble protein. Amino-acid degradation; L-kynurenine degradation. Detected in hepatocytes and in proximal and distal convoluted tubules in kidney cortex (at protein level). Highly expressed in adult liver and in kidney cortex. First detected in embryonic liver after 15 days of development. Belongs to the aldehyde dehydrogenase family.