This product is a highly active, high-purity recombinant bovine enterokinase, produced in *E. coli* and subjected to *in vitro* refolding. It is a proteolytic enzyme with a highly specific cleavage site; it recognizes the sequence DDDDK and cleaves the polypeptide chain at the C-terminal side of the lysine residue. The enzyme can be used to cleave fusion proteins that contain this recognition sequence. Enterokinase retains its activity under a wide range of reaction conditions, effectively cleaving fusion proteins across a broad pH range (4.5–9.5) and temperature range (4–45°C), as well as in the presence of various detergents and denaturing agents. Definition of enzyme activity: One unit is defined as the amount of enzyme that will cleave 95% of 50 μg of fusion protein in 16 hours at 23°C in 1x reaction buffer.
Digestion conditions:
Fusion protein: 0.1 mg
Recombinant enterokinase: 2 U
10x reaction buffer: 10 μl
Temperature (°C): 23
Digestion volume: 100 μl
Duration (hours): 12–16
10x reaction buffer: 500 mM Tris-HCl, pH 8.0; 10 mM CaCl₂; 1% Tween-20 (v/v).