Oxidizes several aliphatic aldehydes, particularly c6-aliphatic aldehyde and hexanal, but does not oxidize benzaldehyde. an aldehyde + H2O + NADP(+) = a carboxylate + 2 H(+) + NADPH an aldehyde + H2O + NAD(+) = a carboxylate + 2 H(+) + NADH Optimum temperature is 55-60 degrees Celsius. Alcohol metabolism; ethanol degradation; acetate from ethanol: step 2/2. Homotetramer. Belongs to the aldehyde dehydrogenase family.