EKMax™ is a recombinant preparation of the catalytic subunit of bovine enterokinase (1). EKMax™ recognizes the sequence Asp-Asp-Asp-Asp-Lys and cleaves the peptide bond after the lysine residue. The enzyme can be used to cleave any fusion protein that carries this peptide sequence (Figure 1).

Application: Removal of fusion tags from recombinant proteins.

Unit Definition: One unit of EKMax™ is the amount of enzyme required to digest 20 μg of a thioredoxin-CAT fusion protein to 90% completion in 16 hours at 37°C. One EKMax™ unit is equivalent to ∼190 trypsinogen activation units.