ARSF (Arylsulfatase F) is a member of the sulfatase gene family, and more specifically, the arylsulfatase subfamily. Sulfatases are essential for the correct composition of bone and cartilage matrix. The activity of this protein, unlike that of arylsulfatase E, is not inhibited by warfarin. Besides, EP300 (E1A binding protein p300) has been identified as an interactor of ARSF, thus a binding ELISA assay was conducted to detect the interaction of recombinant human ARSF and recombinant human EP300. Briefly, ARSF were diluted serially in PBS, with 0.01%BSA (pH 7.4). Duplicate samples of 100uL were then transferred to EP300-coated microtiter wells and incubated for 2h at 37°C. Wells were washed with PBST and incubated for 1h with anti-ARSF pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody, wells were aspirated and washed 3 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37°C. Finally, add 50µL stop solution to the wells and read at 450nm immediately. The binding activity of of ARSF and EP300 was shown in Figure 1, and this effect was in a dose dependent manner.