中国生物工程杂志

Serine protease of hepatitis C virus, which is a key viral non-structural protein and anti-virus target, could degrade HCV polyprotein with cis and trans way to release viral function proteins. Objective To develop a method for evaluating the activities of serine protein or its inhibitors in vitro, a small recombinant peptide( named 2S) as a surrogate of natural substrate of HCV serine protease was designed and its specific sequence was refered to subtype 1a containing amino acid sequences of two linkage sites between HCV NS3 and NS4A, and NS4A and NS4B. A small peptide 2S was expressed finally in prokaryotic cells with GST fusion. Methods 2S gene was synthesized with PCR technique while bath BamH I and EcoR I restriction sites were inserted into 5’ and 3’ ends of the gene. The desired gene was enzymatically performed with BamH I and EcoR I and subcloned into pGEX-4T-2 vector. The recombinant plasmid pGEX-4T-2s was identified with sequencing after transformed into competent cells DH5α.The engineering bacteria was induced overnight by 0.5mM/L IPTG and GST-2S fusion protein was purified with GST affinity column and applied to be degraded with raw protease in phosphate buffer system in vitro. In addition, the catalytic characteristic was analyzed through SDS-PAGE electrophoresis and ELISA. Result The recombinant plasmid pGEX-4T-2s was successfully constructed and the desired protein purified was obtained by affinity column. The detection in PB catalytic system showed that GST-2S belt clearly disappeared with SDS-PAGE and A450 value of the test panel was much lower than positive control with ELISA. Conclusion A small recombinant peptide designed with two cutting sites of HCV serine protease could be degraded by the enzyme in an in vitro system and could be a surrogate as natural substrate HCV serine protease.