EK-Away™ Resin

EKMax enterokinase is a clone of the catalytic subunit of enterokinase expressed in the yeast Pichia pastoris. The calculated molecular weight of the protein is 26.3 kDa, but it contains three sites for asparagine-linked glycosylation. The apparent molecular weight of 43 kDa is consistent with previous observations (LaVallie et al., 1993) and is assumed to be because of N-linked glycosylation.
Reference: LaVallie, E.R., Rehemtulla, A., Racie, L.A.,Diblasio, E.A., Ferenz, C., Grant, K.L. Light, A., and McCoy, J.M. (1993). Cloning and functional expression of a cDNA encoding the catalytic subunit of bovine enterokinase. J.Biol.Chem. 268, 23311-23317.

Enterokinase is active in buffers containing up to 1 mM DTT, 0.1% Triton X-100 detergent, 0.1% Tween 20 detergent, and 0.1% Thesit. It is recommended to have 10mM Tris pH 8.0 and 10 mM calcium chloride in the buffer. Enterokinase is inhibited by sodium chloride and SDS.

Freeze thaw has a minimal effect on the activity of Enterokinase. The addition of glycerol is not necessary but can make handling of the enzyme easier.

Enterokinase cleaves after the sequence (Asp)4-Lys.

It has been proposed that the active center of enterokinase possesses a distinctive cationic subsite that binds -(Asp)4. Enterokinase is highly specific and tolerates very few changes to its recognition site. If the ionic charge of the recognition site is preserved, enterokinase will recognize the site, but the rate of hydrolysis of the peptide bond will be reduced (Light and Janska, 1989). The four aspartyl residues act as a signal for enterokinase cleavage. It has been reported that with only three aspartyl residues the rate of hydrolysis is reduced. Two aspartyl residues preceding the lysyl residue are the minimum number of acidic residues needed to maintain specificity (Maroux et al., 1971). Non-specific cleavage by enterokinase may occur in the cases described above, but this is usually alleviated by reducing the amount of enzyme used.