Enterokinase (also known as enteropeptidase, EC 3.4.21.9) is a key enzyme in the intestine that initiates protein digestion. It specifically recognizes the Asp-Asp-Asp-Asp-Lys (DDDDK) sequence and hydrolyzes the peptide bond at the C-terminus of Lys to activate trypsinogen, thereby initiating the zymogen cascade of the digestive system. Its catalytic activity is effective within the pH range of 4.5-9.5 and temperature range of 4-45°C. Recombinant Enterokinase (Cat#20395ES/20396ES) is a highly purified recombinant bovine enterokinase light chain fragment. Its amino acid sequence is identical to that of the bovine enterokinase light chain, and it possesses the same specific cleavage site as naturally extracted enterokinase. It can be used to remove fusion proteins located at the N-terminus of proteins, thereby eliminating unwanted fusion tags and ensuring the accurate N-terminal sequence of the recombinant fusion protein. This kit uses the double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) principle for the detection of enterokinase residues. Enterokinase standards (20394-B) and test samples are added to a microtiter plate pre-coated with anti-enterokinase antibody (20394-A). Then, diluted biotin-labeled enterokinase detection antibody (20394-C) is added, followed by Streptavidin-HRP (SA-HRP) (20394-D), forming an antibody + antigen + antibody-Biotin + SA-HRP complex. After washing the plate, TMB Substrate Solution (20394-H) is added for color development. TMB is catalyzed by HRP enzyme, changing from colorless to blue, and finally turns yellow under the action of Stop Solution (20394-I). The intensity of the yellow color is positively correlated with the amount of enterokinase detected in the sample. This kit can be used to determine trace residues of recombinant enterokinase in samples from recombinant protein drugs or fusion expression processes where enterokinase cleavage is used. Features The standard curve range is 0.5 ng/mL to 32 ng/mL, with intra-assay precision
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