EK initiates activation of pancreatic proteases by converting trypsinogen to trypsin, which in turn activates chymotrypsin, carboxypeptidases and elastases. Located in the 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 cytoplamic 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. Product Description: This E. coli-derived 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 Cys788-Lys800) with N-terminal Ala, and the light chain (residues Ile801-His1035), UniProt accession P98072. Molecular Mass: Predicted: 1.5kD (heavy cahin C-terminal fragment), 26kD (light chain) Observed (by SDS-PAGE): 34kD(reducing conditions), 30kD (non-reducing conditions) Activity: >35nmol/min/ug Measured by its ability to cleave a colorimetric peptide substrate, N-carbobenzyloxy-Lys-ThioBenzyl ester (Z-Lys-SBzl), in the presence of 5,5-Dithiobis (2-nitrobenzoic acid) (DTNB). Reference: Lu, D. et al. (1997) J. Biol. Chem. 272:31293. Storage and Stability: Store at -20C. Stable for 6 months at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer. To ensure quantitative recovery, we suggest the stock solution be made in the original vial.
