Fusion protein corresponding to the_x000D_ serine protease NS3 (a.a. 3-181) and_x000D_ cofactor NS4A (a.a. 21-32) from Hepatitis_x000D_ C virus genotype 1a (HCV1a), GenBank_x000D_ Accession No. NC_004102, with N-terminal_x000D_ FLAG-His tag, MW = 22.4 kDa,_x000D_ expressed in an E. coli expression_x000D_ system.