Involved in cholesterol degradation. Catalyzes the conversion of propanal to propanoyl-CoA, using NAD(+) and coenzyme A. CoA + NAD(+) + propanal = H(+) + NADH + propanoyl-CoA acetaldehyde + CoA + NAD(+) = acetyl-CoA + H(+) + NADH Monomer. Forms an heterotetramer composed of two aldolase (HsaF) and two dehydrogenase (HsaG) subunits. Belongs to the acetaldehyde dehydrogenase family.