Identification of the major protein adduct formed in rat liver after thioacetamide administration.

The in vivo covalent binding of the hepatocarcinogen thioacetamide to rat liver protein has been examined. Following administration of 3H- or 14C-labeled thioacetamide, the modified amino acids present in the hepatic cytosolic proteins were isolated by enzymatic digestion and ion-exchange chromatography. Approximately 70% of the radioactivity covalently bound to cytosolic protein was recovered in a compound which upon acid hydrolysis yielded lysine and radiolabeled acetate. Additional studies indicated the structure of this adduct was N-epsilon-acetyllysine.