Goat IgG prepared against purified recombinant human P450 1A2, is intended for inhibition studies of P450 1A1/1A2 function using the reconstituted recombinant enzyme or intact human microsomal preparations. Very high inhibition is achieved using recombinant P450 1A2. The observed level of inhibition of P450 1A2 in microsomal preparations is dependent on the specificity of a given substrate for metabolism by P450 1A2, and the relative levels of additional enzymes that may metabolize the test substrate. Also suitable for Western blot.