Identification of the N-acetylcysteine conjugate of benzidine formed in the peroxidase activation system.

Benzidine is oxidized by the peroxidase/H2O2 system, yielding reactive intermediates. In the presence of thiols, covalent adducts are formed. We used h.p.l.c. to separate the products of the reaction of benzidine with N-acetylcysteine. The major product was identified by n.m.r. spectroscopy (1H-n.m.r.) as 3-(N-acetylcystein-S-yl)-benzidine.