UNIT 13B.7 Biochemical Evaluation of HCV NS3 Protease Inhibitors

  1. Brian Schultz,
  2. Huiling Yang,
  3. William E. Delaney IV

Published Online: 1 SEP 2011

DOI: 10.1002/0471141755.ph13b07s54

Current Protocols in Pharmacology

Current Protocols in Pharmacology

How to Cite

Schultz, B., Yang, H. and Delaney, W. E. 2011. Biochemical Evaluation of HCV NS3 Protease Inhibitors. Current Protocols in Pharmacology. 54:B:13B.7:13B.7.1–13B.7.22.

Author Information

  1. Gilead Sciences, Foster City, California

Publication History

  1. Published Online: 1 SEP 2011
  2. Published Print: SEP 2011


This unit describes assays for characterizing the potency and mechanism of action of NS3 protease inhibitors. Determination of IC50 values is described using in vitro expressed and purified NS3 protease. This assay can also be used for the rapid exploration of structure-activity relationships. Another protocol describes using the full-length NS3/4A complexes expressed in HCV replicon cell lines for a rapid alternative method for assessing protease activity without requiring conventional protein expression and purification. A method is then provided for determination of inhibitor Ki, which more accurately assesses the potency of inhibitors compared to the IC50 assay, particularly for potent inhibitors that reach the sensitivity limit for the basic IC50 assay. The final protocol describes how to determine the reversibility of inhibitor binding to the enzyme, an important parameter that can affect the pharmacodynamic properties of a compound. Curr. Protoc. Pharmacol. 54:13B.7.1-13B.7.22. © 2011 by John Wiley & Sons, Inc.


  • hepatitis C virus;
  • NS3 protease;
  • inhibitor