Catalyzes the NAD(+)-dependent oxidation of succinate semialdehyde to succinate. It acts preferentially with NAD as cosubstrate but can also use NADP. Prevents the toxic accumulation of succinate semialdehyde (SSA) and plays an important role when arginine and putrescine are used as the sole nitrogen or carbon sources. H2O + NAD(+) + succinate semialdehyde = 2 H(+) + NADH + succinate H2O + NADP(+) + succinate semialdehyde = 2 H(+) + NADPH + succinate The enzyme reduced NADP at 15 % of the rate of NAD reduction. Optimum pH is 8.2. Activity decreases sharply as the pH is raised above pH 9.2. Amino-acid degradation; 4-aminobutanoate degradation. Homodimer. By p-hydroxyphenylacetate, succinate semialdehyde (SSA) and putrescine. Highly expressed under several stress conditions together with many genes related to the metabolism of nitrogen compounds. Cells are unable to grow on 4-hydroxyphenylacetate. Belongs to the aldehyde dehydrogenase family.