Hepatitis C Virus S5A/5B is a synthetic peptide substrate. Hepatitis C Virus S5A/5B mimics the NS5A/5B junction of the nonstructural protein (NS), served as the substrate for the study of HCV NS3 protease activity[1].
References
[1] Shimizu Y, et al. Identification of the sequence on NS4A required for enhanced cleavage of the HCV NS3 site by hepatitis C virus NS3 protease. J Virol. 1996 Jan;70(1):127-32. DOI:10.1128/JVI.70.1.127-132.1996