N-Acetyltransferase 2 (NAT2) ) is an enzyme that plays an important role in metabolism and detoxification of many compounds including drugs and environmental carcinogens through chemical modification of the amine group with an acetyl group. Cytochrome P4502E1 (CYP2E1) and NAT2 are related to chronic obstructive pulmonary disease and CYP2E1 can bind to NAT2. Thus a functional binding ELISA assay was conducted to detect the interaction of recombinant rat NAT2 and recombinant mouse CYP2E1. Briefly, NAT2 was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to CYP2E1-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-NAT2 pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 µL stop solution to the wells and read at 450/630 nm immediately. The binding activity of recombinant rat NAT2 and recombinant mouse CYP2E1 was shown in Figure 1, the EC50 for this effect is 0.096 ug/mL.