ENTEROKINASE

Uses

Typical conditions for fusion protein cleavage:
Adjust the concentration of the fusion protein to 1.5 mg/ml and a pH between 7.0-8.0 with 500 mM Tris-HCl, pH 8.0, 2.0 mM CaCl_2, and 1% Tween^? 20
Add enterokinase to fusion protein solution at a ratio of ~ 0.02 units per 1 mg fusion protein and mix
Incubate reaction mixture at ~25 °C for 16 hours

Definition

An enzyme found in the small intestine, which converts trypsinogen into trypsin.

General Description

Enterokinase is a highly specific serine protease that is used for the removal of the FLAG peptide from N-terminal and Met-N-terminal fusion proteins. It does not remove the C-terminal FLAG.

Biochem/physiol Actions

Enterokinase is a membrane bound serine protease that specifically and rapidly converts trypsinogen to trypsin, thereby, triggering the conversion of other zymogens to active enzymes. It has a molecular mass of approximately 150 kDa. The enzyme is a heterodimer consisting of 35-47 kDa subunits. The light and the heavy chains are linked by two disulfide bridges. It is a glycoprotein containing 35% carbohydrate. The polypeptide chain of trypsinogen is hydrolyzed only after an -(Asp)4-Lys- sequence. The enzyme is inhibited by soybean trypsin inhibitor. Enterokinase is typically used in protein modification and amino acid sequence determination.