Have you ever questioned the quality or reproducibility of your recombinant growth factors or cytokines? Learn more about the testing we do to ensure that our recombinant proteins are bioactive and stable.

First, each lot is tested to ensure it is >95% pure, filtered, endotoxin tested, and run on gels to confirm the molecular weight. Next, we perform a relevant bioassay, such as proliferation or cytokine production assays, to ensure the product is bioactive. We also perform testing to ensure our proteins are stable after multiple freeze-thaws and during long-term storage.

Recombinant Mouse TIGIT-Fc Chimera Recombinant Rat TNF-α
Recombinant protein was aliquoted in PBS pH 7.2 at 0.2 mg/mL. Aliquots were frozen and thawed four times (4x Freeze/Thaw) or kept at 4°C, RT, or 37°C for one week. Recombinant CD155 binding to immobilized TIGIT was measured. Recombinant proteins stored at -80°C for 10 years were tested for bioactivity as compared to a fresh competitor lyophilized protein. The ability of Rat TNF-α to induce cytotoxicity of L929 cells was measured.

The majority of our recombinant proteins are provided in a liquid format with a comparable shelf-life to lyophilized proteins. Advantages of a liquid format include:

  • Ready-to-use
  • Longer in-use shelf life
  • No buffer preparation or pH adjustment
  • No filtration
  • Reduced chance for contamination
  • No risk of protein aggregation during reconstitution

Reported activity values for recombinant proteins can be difficult to interpret as they depend on the specific assay and conditions used to generate those values. To make comparing activity values easier, we’re testing our recombinants against international standards. Keep an eye out, as we continue to test more proteins, we'll be adding this information to each product TDS.

Protein NIBSC Reference Standard Specific Activity (IU/µg)
Human IL-2 86/500 2.36 x 104
Human IL-3 91/510 1.64 x 103
Human IL-12 (p70) 95/544 1.32 x 104
Human GM-CSF 88/646 1.60 x 104
Human TNF-α 12/154 5.35 x 104
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