Reactivity | BvSpecies Glossary |
Applications | Enzyme Activity |
Format | Carrier-Free |
Details of Functionality | Measured by its ability to cleave a colorimetric peptide substrate, N-carbobenzyloxy-Lys-ThioBenzyl ester (Z-Lys-SBzl), in the presence of 5,5’Dithio-bis (2-nitrobenzoic acid) (DTNB). Lu, D. et al. (1997) J. Biol. Chem. 272:31293. The specific activity is >35 nmol/min/µg, as measured under the described conditions. |
Source | E. coli-derived bovine Enteropeptidase/Enterokinase protein Cys788-Lys800 (heavy chain C-terminal fragment) with an N-terminal Ala, & Ile801-His1035 (light chain) |
Accession # | |
N-terminal Sequence | Ala & Ile801 |
Structure / Form | Disulfide-linked heterodimer |
Protein/Peptide Type | Recombinant Enzymes |
Purity | >90%, by SDS-PAGE under reducing conditions and visualized by silver stain |
Endotoxin Note | <1.0 EU per 1 μg of the protein by the LAL method. |
Dilutions |
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Theoretical MW | 1.5 kDa (heavy chain C-terminal fragment), 26 kDa (light chain). Disclaimer note: The observed molecular weight of the protein may vary from the listed predicted molecular weight due to post translational modifications, post translation cleavages, relative charges, and other experimental factors. |
SDS-PAGE | 34 kDa, reducing conditions 30 kDa, non-reducing conditions |
Storage | Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
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Buffer | Supplied as a 0.2 μm filtered solution in Glycerol, NaCl and HEPES. |
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Purity | >90%, by SDS-PAGE under reducing conditions and visualized by silver stain |
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Assay Procedure |
*Adjusted for Substrate Blank **Using the extinction coefficient 13260 M-1cm-1 ***Using the path correction 0.32 cm Note: the output of many spectrophotometers is in mOD Per Well:
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EK initiates activation of pancreatic proteases by converting trypsinogen to trypsin, which in turn activates chymotrypsin, carboxypeptidases and elastases. Located in intestinal brush border, it is a disulfide bond linked dimer of the heavy and light chains, which are derived from the same single-chain precursor. The multidomain‑containing heavy chain consists of a short cytoplasmic tail, a transmembrane, a SEA, a SRCR, a MAM, two CUB and two LDL-receptor class A domains. The light chain contains the catalytic domain of trypsin-like serine proteases. The purified recombinant bovine EK (residues 788-1035) corresponds to a disulfide bond‑linked dimer that consists of the C-terminal fragment of the heavy chain (residues 788-800) and the light chain (residues 801-1035). rbEnterokinase can cleave fusion proteins having an accessible Enterokinase cleavage site (DDDDK). At an average ratio for fusion protein:rbEnterokinase of 1000:1 (w/w), cleavage up to 90% completion is achieved within one hour at room temperature. Non-specific cleavage at basic residues has also been observed for some proteins. It is recommended that cleavage reaction be optimized for each fusion protein. The reaction may be terminated by passing the sample through a soybean trypsin inhibitor (SBTI)-agarose affinity column (e.g. Sigma Catalog # T0637 ) to remove the rbEnterokinase from the reaction mixture. SBTI inhibits rbEnterokinase with a Ki of 1.6 nM.
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