Meprin A alpha (MEP1a) is a metalloprotease belonging to the astacin family, primarily expressed in the kidney, intestine, and immune cells. It plays a crucial role in extracellular matrix remodeling, inflammation, and epithelial barrier function by cleaving substrates such as collagen, cytokines, and adhesion molecules. MEP1a is synthesized as a zymogen and activated through proteolytic processing. It forms heterodimers with Meprin A beta (MEP1b), which stabilizes the complex and modulates substrate specificity.To detect the activity of recombinant MEP1a, a functional ELISA assay was performed to evaluate the interaction between recombinant human IMEP1a and recombinant rat MEP1b.Briefly, MEP1a was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to MEP1b-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-MEP1a 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 450/630nm immediately. The binding activity of recombinant human IMEP1a and recombinant rat MEP1b was shown in Figure 1, the EC50 for this effect is 0.048µg/mL.