NS3 protease of hepatitis C virus (HCV), located on the N-terminal domain of HCV NS3, is responsible for the cleavage at the NS3/NS4A, NS4A/NS4B, NS4B/NS5A, and NS5A/NS5B sites of the nonstructural protein. The HCV NS3 is a chymotrypsin-like serine protease. It requires a cofactor, a 54 amino acid NS4 protein, to reach its optimal activity. The X-ray crystal structure studies show that NS3 forms a tight non-covalent complex with NS4. The NS3/4A protease is essential for viral replication and the formation of infectious viral particles, and thus has been considered as one of the most attractive targets for anti-HCV therapy.
The recombinant HCV NS3/4A protease (genotype 1b, strain: HC-J4; NCBI Accession: AF054247) was expressed in E. Coli. HCV NS3/4A protease is a 217 amino acid fusion protein (22.7 kDa) with NS4A co-factor fused to the N-terminus of NS3 protease domain. Therefore, HCV NS3/4A protease is in active form and the pre-activation by pep4A or pep4AK is not necessary. 5-20 ng of HCV NS3/4A protease is sufficient for FRET-based activity assays (SensoLyte® HCV protease assay).
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20 mM Tris-HCl, pH 8.0, 20% Glycerol, 100 mM KCl, 1 mM DTT and 0.2 mM EDTA.
Store at -80 ºC. Avoid repeated freeze-thaw cycles.