A Model System of Cytochrome P-450 : Hydroxylation of Aniline by Iron- or Hemin-Thiol Compound Systems

Hydroxylation of aniline by several Fe (II)-thiol and hemin-thiol complexes was studied as a model system for cytochrome P-450 in liver microsomes. Cysteine, cysteine methylester, cysteamine, N-acetyl-cysteine, α-mercaptopropionic acid, β-mercapto-propionic acid, thiosalicylic acid and o-aminobenzenethiol were tested as thiolcompounds. In these systems, p-and o-aminophenol were the major products and m-aminophenol was not detected. The hydroxylation was affected by reaction time, pH, the type of thiol compound and the concentrations of thiol compound, aniline, Fe (II) and hemin. The aniline-hydroxylating activity of the hemin-thiol system was 6-20 times that of the Fe (II)-thiol system at pH 4. The Fe (II)-thiol and hemin-thiol systems may be useful chemical models for studies of the structure and function of cytochrome P-450.