SAB Enterokinase is a kind of highly purified recombinant bovine enterokinase light chain. The enzyme has been extensively purified by HPLC and there are no traces of other contaminating proteases. Enterokinase specifically hydrolyzes peptide bond at the carboxyl side of lysine residue preceded by four aspartic acids: Asp-Asp-Asp-Asp-Lys (DDDDK). So, enterokinase can remove N-terminal fusion protein or tags to get aim protein with native amino acids sequence.