Covalent binding of photo-oxidized benz[alpha] anthracene and related carcinogenic hydrocarbons to protein

Carcinogenic hydrocarbons benz[alpha] anthracene (BA), 7,12-dimethyl-BA (DMBA) and 3-methylcholanthrene (MC), bound non-covalently to bovine serum albumin (BSA), are photo-oxidized and become covalently bound to the protein as a result of irradiation at 365 nm. BSA with covalently-bound hydrocarbon photoproducts can be isolated by SDS-gel filtration after repeated ether extraction. In this photo-oxidation, BA and DMBA are converted apparently to phenanthrene-type products together with some other photoproduct in the case of BA, whereas MC produced a naphthalene-like photoproduct and an intact molecule bound to BSA. Our findings suggest that these hydrocarbons can undergo photo-activation and macromolecular binding as in metabolic activation.