Nonidentity of liver alcohol dehydrogenase and the principal protein target of hepatic azocarcinogen

During hepatocarcinogenesis in the rat by the aminoazo dyes, a principal carcinogen-protein conjugate (azoprotein) is formed in liver cytosol from a normal target protein, whose identity and function are unknown. Based on similarities of amino acid compositions, molecular weights, and subunit sizes of azoprotein and liver alcohol dehydrogenases, others have proposed that liver alcohol dehydrogenase is the principal normal target protein of azocarcinogens during liver carcinogenesis in the rat.In the present study, specific antiserum precipitated the principal liver azoprotein and target protein, but failed to precipitate rat liver alcohol dehydrogenase. The ability of the antiserum to distinguish and to separate the azoprotein and target protein from alcohol dehydrogenase shows that this enzyme is not the principal target protein of the azocarcinogens.