This substrate for this enzyme is formed by meta ring cleavage of catechol (EC 1.13.11.2, catechol 2,3-dioxygenase), and is an intermediate in the bacterial degradation of several aromatic compounds. Has lower activity with benzaldehyde [1]. Activity with NAD+ is more than 10-fold higher than with NADP+ [3]. cf. EC 1.2.1.32, aminomuconate-semialdehyde dehydrogenase.