Merck, SAE0147-5KU, Thrombin protease, biotin-tagged

General description
Thrombin is an endolytic serine protease that selectively cleaves the Arg–Gly bonds of fibrinogen to form fibrin and release fibrinopeptides A and B.1,2
The optimal cleavage sites for thrombin are as follows:
1. A-B-Pro-Arg-||-X-Y, where A and B are hydrophobic amino acids, and X and Y are nonacidic amino acids.
2. Gly-Arg-||-Gly
Recombinant human thrombin protease is expressed in human HEK 293 cells as a glycoprotein heterodimer. The DTT-reduced protein migrates as two bands of ∼31 kDa (heavy chain) and ∼6 kDa (light chain) on SDS-PAGE. This protein is manufactured in human cells, with no serum. The human cells expression system allows human-like glycosylation and folding, and often supports higher activity of the protein.
This thrombin protease is useful for cleaving recombinant proteins that are expressed as fusion proteins with this sequence between the carrier domain and the protein of interest.
Application
This biotinylated thrombin protease can be used for on-column cleavage of fusion proteins with a thrombin cleavage site. It specifically cleaves the protein of interest from a column-bound fusion protein, leaving the fusion domain or tag bound to the affinity column (e.g., Ni-NTA column) and eluting only the protein of interest.
This method is advantageous over post-elution cleavage for several reasons:

• It eliminates most impurities normally associated with purification on Ni-chelating columns.
• It allows gentler elution conditions, with added flexibility in the elution buffer composition. This can mitigate protein aggregation and inactivation.

After cleavage, the protease can be removed with any avidin-conjugated or streptavidin-conjugated beads.
Features and Benefits
The product is supplied in an aqueous buffer of pH 6.0, with 50% (v/v) glycerol.
Catalytic pH range:11.5–10
Optimal pH:11-8.3
(Note: thrombin precipitates at pH ≤5)
Molecular mass:4,12 37.4 kDa
Human isozymes pI range:6.35–7.6
E280 (1%):12 -18.3
This Thrombin protease, biotin-tagged enables on-column cleavage of fusion proteins with a thrombin cleavage site.