“…The two arylamine substrates that were not oxidized by the microsomal system are extremes with respect to the electronic properties of arylamines. The amine group of 4-nitroaniline is a much weaker base than most arylamines (Rao et al, 1979) and has a substantially reduced electron density on the amine nitrogen relative to that of the other arylamines in Table I (Loew et al, 1979). These properties of 4-nitroaniline could explain the failure of the microsomal enzyme to effect N-oxidation.…”