Identification of a cysteinyl adduct of oxidized 3-methylindole from goat lung and human liver microsomal proteins

3-Methylindole is a selective pneumotoxin that is oxidized by cytochrome P-450 ensymes to a reactive intermediate. 3-Methyleneidolenine, a methylene imine electrophile, is the postulated reactive intermediate, and it binds to proteins, a reaction that probably initiates the pneumotoxicity of 3-methylindole. Thioether adducts of this electrophile are formed with glutathione in vitro, but the identity of the adducted electrophile with amino acid residues of microsomal proteins had not previously been determined