Human CD26 protein, His tag

Dipeptidyl peptidase-4 (DPP4), also known as adenosine deaminase complexing protein 2 or cluster of differentiation 26 (CD26), is a protein in humans. DPP4 is an antigenic enzyme expressed on the surface of most cell types and is associated with immune regulation, signal transduction and apoptosis. It is an intrinsic membrane glycoprotein and a serine exopeptidase that cleaves X-proline dipeptides from the N-terminus of polypeptides. Besides, Eosinophil Chemotactic Factor (ECF) has been identified as an interactor of DPP4, thus a binding ELISA assay was conducted to detect the interaction of recombinant human DPP4 and recombinant human ECF. Briefly, DPP4 were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to ECF-coated microtiter wells and incubated for 2h at 37ºC. Wells were washed with PBST and incubated for 1h with anti-DPP4 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 37ºC. Finally, add 50 μl stop solution to the wells and read at 450nm immediately. The binding activity of DPP4 and ECF was in a dose dependent manner.