It has been shown in numerous studies that mutagenic heterocyclic amines are present in the pyrolysates of amino acids, peptides, and proteins and in cooked foods.'In 1986, a new mutagen was isolated from cooked beep which was determined to be 2-amino-1-methyl-6- phenylimidazo-[4, 5-b] pyridine (PhIP, la) by spectral evidence2 and synthetic study. 3 A few years later, closely related 2-amino-1, 6-dimethylimidazo [4, 5-b] pyridine (DMIP, lb) was ...