Cytochrome P-450 metabolic-intermediate complex formation from p-aminobenzoic acid esters and other arylamines.

Metabolism of a series of p-aminobenzoic acid esters by rat liver microsomal fractions resulted in the formation of cytochrome P-450 metabolic - intermediate complexes. With conditions that allowed complex formation to proceed to completion, about 20% of control rat cytochrome P-450 was sequestered as a complex. Phenobarbital, but not beta-naphthoflavone induced additional cytochrome P-450, which with specific esters could be complexed to about 60%. For other esters, the induced cytochrome maximally complexed to about 20%, as was seen in uninduced rats. The two groups of p-aminobenzoic acid esters could not be readily delineated by lipid/water partition coefficients or steric factors.