Alcohol ehydrogenase (ADH) is an enzyme discovered in the mid-1960s in Drosophila melanogaster. Since then, there has been extensive research on the enzyme. Alcohol dehydrogenase is a dimer, weighing 80,000 g/mol.Alcohol dehydrogenases (EC 1.1.1.1) are a group of seven dehydrogenase enzymes that occur in many organisms and facilitate the interconversion between alcohols and aldehydes or ketones with the reduction of NAD+ to NADH. In humans and many other animals, they serve to break down alcohols which could otherwise be toxic; in yeast and many bacteria, some alcohol dehydrogenases catalyze the opposite reaction as part of fermentation.