Verified vs. Unverified Recombinant Proteins: Making the Right Choice for Your Research

1. What Are Verified Recombinant Proteins?

The term "verified" typically refers to recombinant proteins that have undergone rigorous testing and validation to confirm their biological activity. So verified recombinant proteins can be simply considered active recombinant proteins.

Commercially verified recombinant proteins are generally tested for endotoxin content and purity in addition to activity verification.

The activity of recombinant proteins may be affected by misfolding or incomplete folding, post-translational modifications, and purification conditions during the production process. These factors may cause the recombinant protein to have little or no activity.

Validating the activity of recombinant proteins is particularly important in biological and biochemical research, which ensures that the activity of the protein is consistent with expectations, guaranteeing accurate, reliable, and reproducible results.

2. What Are Unverified Recombinant Proteins?

In contrast, the activity of unverified recombinant proteins is unknown, inconsistent, or different from what is expected. They ma ybe active or have no activity. Unverified recombinant proteins are produced in the same way as verified counterparts but lack comprehensive validation.

Of course, you can also validate the activity of unverified recombinant proteins. However, the verification processes are complicated and time-consuming.

3. Which Types of Experiments Are Verified Recombinant Proteins Suitable for?

Verified recombinant proteins are biologically active and known to function as intended, such as binding to a specific receptor, reacting with an antibody, catalyzing a reaction, or interacting with other molecules. So verified recombinant proteins are essential for functional studies, drug development and testing, and in vivo studies.

3.1 Functional Studies

① Cell-based Assays

Verified active recombinant proteins are often used in cell-based assays to investigate how they influence various cellular functions, including cell proliferation, differentiation, apoptosis, and migration.

② Enzyme Activity Assays

Active recombinant enzymes are employed to assess enzymatic functions such as kinase activity, protease activity, or other catalytic processes. They are essential in studying reaction mechanisms, substrate specificity, and the effects of inhibitors or activators.

③ Receptor Binding Studies

Active recombinant ligands or hormones can be used to study receptor-ligand interactions, signal transduction pathways, or receptor activation in cell cultures.

④ Protein-Protein Interaction Studies

Validated active recombinant proteins are used in techniques such as co-immunoprecipitation (co-IP), surface plasmon resonance (SPR), or pull-down assays, helping to map interaction networks and determine binding affinities between proteins.

3.2 Drug Screening and Development

Validated active recombinant proteins serve as targets in high-throughput screening of potential drug candidates. Researchers can use active recombinant proteins to study drug-protein interactions in a simulated physiological condition and test compound efficacy. For regulatory submissions or clinical trials, verified proteins are often required to meet stringent quality standards.

A study demonstrated the use of recombinant trimeric SARS-CoV-2 spike (S) protein in a cell-free system to screen for compounds that inhibit its binding to ACE2, highlighting the utility of recombinant proteins in identifying potential therapeutics for viral infections ^[1]. This approach minimizes cytotoxic effects associated with live-virus assays and allows for a focused investigation of drug efficacy ^[1].

3.3 In Vivo Studies

Active recombinant proteins can be administered to animal models to study their physiological effects, such as inducing a response in gene expression or metabolism.

4. Which Types of Experiments Are Unverified Recombinant Proteins Suitable for?

Unverified recombinant proteins have uncertainty in their activity. If they do not function as anticipated, it may result in misleading results or require additional controls to determine whether observed effects are due to the proteins themselves or other factors.

So unverified recombinant proteins are suitable for experiments where the functionality of the protein is not required, including structural studies, protein folding and stability studies, antibody production, and control experiments.

4.1 Structural Analysis

In X-ray crystallography and NMR, unverified recombinant proteins are used to determine the protein structure, providing a clear view of the protein’s architecture. Unverified recombinant proteins are employed in cryo-electron microscopy to visualize the protein's structure, particularly when the active conformation might be too flexible.

4.2 Protein Folding and Stability Studies

Unverified recombinant proteins can be used to study protein folding, misfolding, and refolding mechanisms. They also invest in research on protein stability and aggregation without the interference of enzymatic or binding activities.

4.3 Antibody Production

Unverified recombinant proteins can be used as immunogens for generating antibodies. Immunizing animals with recombinant protein can produce and obtain antibodies. When preparing antibodies, recombinant proteins with high purity should be selected. The higher the protein purity, the easier to prepare high-performance specific antibodies against the target protein.

4.4 Control Experiments

Unverified recombinant proteins can serve as negative controls in functional assays to confirm that observed effects are due to the active form of the protein. They also help to validate the specificity and sensitivity of assays designed to detect active proteins.

Conclusion

Different types of experiments have different requirements for protein performance. The choice for different types of recombinant proteins depends on whether the protein's activity is essential or potentially disruptive to the experiment's goals. Verified recombinant proteins are suitable for studies requiring biological function while unverified recombinant proteins are selected for those that do not need biological activity.

CUSABIO provides a large number of active recombinant proteins, including cytokines, drug target proteins, enzymes, hormones, and other proteins. The majority of them are characterized by high purity, low endotoxin, and active verification. If you just conduct some basic research such as structural analyses and control experiments, we also offer unverified recombinant proteins that are more cost-effective than active counterparts.

References

[1] Tsegay KB, Adeyemi CM, et al A Repurposed Drug Screen Identifies Compounds That Inhibit the Binding of the COVID-19 Spike Protein to ACE2 [J]. Front Pharmacol. 2021 Jun 14;12:685308.