a primary alcohol + NAD(+) = an aldehyde + H(+) + NADH a secondary alcohol + NAD(+) = a ketone + H(+) + NADH Binds 2 Zn(2+) ions per subunit. Stomach and liver. There are 7 different ADH's isozymes in human: three belongs to class-I: alpha, beta, and gamma, one to class-II: pi, one to class-III: chi, one to class-IV: ADH7 and one to class-V: ADH6. Belongs to the zinc-containing alcohol dehydrogenase family. Class-V subfamily.