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#C1210N 3CLPro L50F + E166A + L167F Expression Kit


Express 3CLpro with the L50F + E166A + L167F mutation in mammalian cells including HEK293, A549, and many more. Use alongside other 3CLpro mutant proteases and our 3CLglow biosensor assays to test 3CLpro inhibitor efficacy against a panel of mutations in the protease.



3CLpro (Mpro) L50F + E166A + L167F mutation Expression Kit

In biochemical analysis, nirmatrelvir’s IC50 value was found to be 72-fold greater in the presence of the L50F, E166A, L167F mutation (Jochmans et al. 2023). In a HEK293T cell-based 3CLpro fluorescent reporter assay nirmtrelvir EC50 increased from .96uM to 27uM with this mutation (Jochmans et al. 2023). These mutations occur independently in patients and have emerged collectively when passing the virus under nirmatrelvir selection (Jochmans et al. 2023; Shu and McCauley 2017). Furthermore, a FRET-based enzymatic assay demonstrated a 51.9-fold increase in IC50 values for nirmatrelvir in the presence of this mutation (Huang et al. 2023).

  • Identify protease inhibitors that maintain efficacy against the L50F + E166A + L167F mutation
  • Easy co-expression with our 3CLglow and 3CLglowUp sensors
  • Cost effective screening with minimal safety requirements (BSL-1)

Materials in the Kit:

• 3CLpro L50F + E166A + L167F in BacMam
• Sodium Butyrate, 500 mM in H2O


Huang, C., Shuai, H., Qiao, J., Hou, Y., Zeng, R., Xia, A., Xie, L., Fang, Z., Li, Y., Yoon, C., Huang, Q., Hu, B., You, J., Quan, B., Zhao, X., Guo, N., Zhang, S., Ma, R., Zhang, J., … Yang, S. (2023). A new generation mpro inhibitor with potent activity against SARS-COV-2 omicron variants. Signal Transduction and Targeted Therapy, 8(1).

Jochmans, D., Liu, C., Donckers, K., Stoycheva, A., Boland, S., Stevens, S. K., De Vita, C., Vanmechelen, B., Maes, P., Trüeb, B., Ebert, N., Thiel, V., De Jonghe, S., Vangeel, L., Bardiot, D., Jekle, A., Blatt, L. M., Beigelman, L., Symons, J. A., … Vandyck, K. (2023). The substitutions L50F, E166A, and L167F in SARS-COV-2 3clpro are selected by a protease inhibitor in vitro and confer resistance to Nirmatrelvir. mBio, 14(1).

Shu, Y., & McCauley, J. (2017). GISAID: Global initiative on sharing all influenza data – from vision to reality. Eurosurveillance, 22(13).

Additional information


We strive for prompt delivery of each order, so we ship by FedEx 2-day service in lightweight, sturdy, and reusable/biodegradable packaging with an insulated cooler and moisture-resistant refrigerant gel packs. Shipping days are Mon-Wed so product does not sit in transit over the weekend. Web store ships to US & Canada only, contact sales for other locations.

Protocol for Use


Kit Volume

5mL, 30mL

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