Prostaglandin H synthase-mediated reaction of carcinogenic arylamines with tRNA and homopolyribonucleotides.

Prostaglandin H synthase mediates the reaction of an extensive series of carcinogenic arylamines with tRNA. Structure-activity relationships suggest that benzidine is especially reactive due to extended conjugation between the 4,4'-diamino groups. In trapping experiments with homopolyribonucleotides, benzidine reacts with polyguanylic acid but 4-aminobiphenyl reacts with polycytidylic acid. The nitrenium ion of 4-aminobiphenyl (formed by N,O-acyltransferase activation of N-hydroxy-4-acetylaminobiphenyl) reacts primarily with polyguanylic acid and to a lesser extent with polyadenylic acid. The results suggest that arylamine activation by prostaglandin H synthase does not involve nitrenium ion formation.