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#C1201N 3CLPro L50F Expression Kit


Express 3CLpro with the L50F 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 mutation Expression Kit

L50F is a compensatory substitution that aids in maintaining the virus’s fitness (Jochmans et al. 2023; Zhou et al. 2022; Iketani et al. 2023). In a recombinant SARS-CoV-2 assay conducted in huh7-ACE2 cells, L50F has a 4.2-fold resistance to nirmatrelvir (Iketani et al. 2023). Structurally, the L50F mutation is located in the S2 subsite of 3CLpro and demonstrates increased catalytic activity compared to wild-type 3CLpro in kinetic assays (Duan et al. 2023). This mutation has been detected in patients and documented in the GISAID database (Shu and McCauley 2017).

  • Identify protease inhibitors that maintain efficacy against the L50F 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 in BacMam

• Sodium Butyrate, 500 mM in H2O


Duan, Y., Zhou, H., Liu, X., Iketani, S., Lin, M., Zhang, X., Bian, Q., Wang, H., Sun, H., Hong, S. J., Culbertson, B., Mohri, H., Luck, M. I., Zhu, Y., Liu, X., Lu, Y., Yang, X., Yang, K., Sabo, Y., … Yang, H. (2023). Molecular mechanisms of SARS-COV-2 resistance to Nirmatrelvir. Nature, 622(7982), 376–382.

Iketani, S., Mohri, H., Culbertson, B., Hong, S. J., Duan, Y., Luck, M. I., Annavajhala, M. K., Guo, Y., Sheng, Z., Uhlemann, A.-C., Goff, S. P., Sabo, Y., Yang, H., Chavez, A., & Ho, D. D. (2023). Multiple pathways for SARS-COV-2 resistance to Nirmatrelvir. Nature, 613(7944), 558–564.

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).

Zhou, Y., Gammeltoft, K. A., Ryberg, L. A., Pham, L. V., Tjørnelund, H. D., Binderup, A., Duarte Hernandez, C. R., Fernandez-Antunez, C., Offersgaard, A., Fahnøe, U., Peters, G. H., Ramirez, S., Bukh, J., & Gottwein, J. M. (2022). Nirmatrelvir-resistant SARS-COV-2 variants with high fitness in an infectious cell culture system. Science Advances, 8(51).

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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