Recombinant SARS-CoV-2 CAL.20C S1 Subunit His Protein, CF

Recombinant SARS-CoV-2 CAL.20C Spike S1 Subunit His-tag (Catalog # 10779-CV) binds Recombinant Human ACE-2 His-tag (933-ZN) in a functional ELISA.

2 μg/lane of Recombinant SARS-CoV-2 CAL.20C S1 Subunit His-tag (Catalog # 10779-CV) was resolved with SDS-PAGE under reducing (R) and non-reducing (NR) conditions and visualized by Coomassie® Blue staining, showing bands at 105-117 kDa.

Recombinant SARS-CoV-2 CAL.20C variant Spike protein S1 subunit was immobilized on a Biacore Sensor Chip CM5, and binding to recombinant human ACE-2 (933-ZN) was measured at a concentration range between 0.046 nM and 47.2 nM. The double-referenced sensorgram was fit to a 1:1 binding model to determine the binding kinetics and affinity, with an affinity constant of KD=1.040 nM.

• Reactivity: V
• Applications: Bioactivity
• Format: Carrier-Free

Recombinant SARS-CoV-2 CAL.20C S1 Subunit His Protein, CF Summary

• Additional Information: W152C, L452R, D614G
• Details of Functionality: Measured by its binding ability in a functional ELISA with Recombinant Human ACE-2 His-tag (Catalog # 933-ZN).
• Source: Human embryonic kidney cell, HEK293-derived sars-cov-2 Spike S1 Subunit protein
  Val16-Pro681 (Trp152Cys, Leu452Arg, Asp614Gly), with a C-terminal 6-His tag
• Accession #: YP_009724390.1
• N-terminal Sequence: Val16
• Protein/Peptide Type: Recombinant Proteins
• Purity: >95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
• Endotoxin Note: <0.10 EU per 1 μg of the protein by the LAL method.

Applications/Dilutions

• Dilutions:
  • Bioactivity
• Theoretical MW: 75 kDa.
  Disclaimer note: The observed molecular weight of the protein may vary from the listed predicted molecular weight due to post translational modifications, post translation cleavages, relative charges, and other experimental factors.
• SDS-PAGE: 105-117 kDa, under reducing conditions

Packaging, Storage & Formulations

• Storage: Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
  • 12 months from date of receipt, -20 to -70 °C as supplied.
  • 1 month, 2 to 8 °C under sterile conditions after reconstitution.
  • 3 months, -20 to -70 °C under sterile conditions after reconstitution.
• Buffer: Lyophilized from a 0.2 μm filtered solution in PBS with Trehalose.
• Purity: >95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
• Reconstitution Instructions: Reconstitute at 500 μg/mL in PBS.

Notes

This product is produced by and ships from R&D Systems, Inc., a Bio-Techne brand.

Alternate Names for Recombinant SARS-CoV-2 CAL.20C S1 Subunit His Protein, CF

• 2019-nCoV S Protein
• 2019-nCoV Spike
• COVID-19 Spike
• E2
• Human coronavirus spike glycoprotein
• Peplomer protein
• S glycoprotein
• S Protein
• SARS-COV-2 S protein
• SARS-COV-2 Spike glycoprotein
• SARSCOV2 Spike protein
• SARS-CoV-2
• Severe Acute Respiratory Syndrome Coronavirus 2 Spike Protein
• Spike glycoprotein
• Spike
• surface glycoprotein

Background

SARS-CoV-2, which causes the global pandemic coronavirus disease 2019 (Covid-19), belongs to a family of viruses known as coronaviruses that are commonly comprised of four structural proteins: Spike protein(S), Envelope protein (E), Membrane protein (M), and Nucleocapsid protein (N) (1). SARS-CoV-2 Spike Protein (S Protein) is a homotrimeric glycoprotein that mediates membrane fusion and viral entry. As with most coronaviruses, proteolytic cleavage of the SARS-CoV-2 S protein into two distinct peptides, S1 and S2 subunits, is required for activation. The S1 subunit is focused on attachment of the protein to the host receptor while the S2 subunit is involved with cell fusion (2-5). A SARS-CoV-2 variant (named CAL.20C) carrying the S1 subunit amino acid (aa) change W152C, L452R, and D614G emerged in Southern Califonia (6,7). Based on structural biology studies, the receptor binding domain (RBD), located in the C-terminal region of S1, can be oriented either in the up/standing or down/lying state (8). The standing state is associated with higher pathogenicity and both SARS-CoV-1 and MERS can access this state due to the flexibility in their respective RBDs. A similar two-state structure and flexibility is found in the SARS-CoV-2 RBD (9). Based on amino acid (aa) sequence homology, the SARS-CoV-2 S1 subunit has 65% identity with SARS-CoV-1 S1 subunit, but only 22% homology with the MERS S1 subunit. The low aa sequence homology is consistent with the finding that SARS and MERS bind different cellular receptors (10). The S Protein of the SARS-CoV-2 virus, like the SARS-CoV-1 counterpart, binds Angiotensin-Converting Enzyme 2 (ACE-2), but with much higher affinity and faster binding kinetics (11). Before binding to the ACE-2 receptor, structural analysis of the S1 trimer shows that only one of the three RBD domains in the trimeric structure is in the "up" conformation. This is an unstable and transient state that passes between trimeric subunits but is nevertheless an exposed state to be targeted for neutralizing antibody therapy (12). Polyclonal antibodies to the RBD of the SARS-CoV-2 S1 subunit have been shown to inhibit interaction with the ACE-2 receptor, confirming S1 subunit especially the RBD as an attractive target for vaccinations or antiviral therapy (13). There is also promising work showing that the RBD may be used to detect presence of neutralizing antibodies present in a patient's bloodstream, consistent with developed immunity after exposure to the SARS-CoV-2 virus (14). Lastly, it has been demonstrated the S Protein can invade host cells through the CD147/EMMPRIN receptor and mediate membrane fusion (15, 16).

1. Wu, F. et al. (2020) Nature 579:265.
2. Tortorici, M.A. and D. Veesler (2019) Adv. Virus Res. 105:93.
3. Bosch, B.J. et al. (2003) J. Virol. 77:8801.
4. Belouzard, S. et al. (2009) Proc. Natl. Acad. Sci. 106:5871.
5. Millet, J.K. and G.R. Whittaker (2015) Virus Res. 202:120.
6. Zhang, W. et al. (2021) JAMA https://doi.org/10.1001/jama.2021.1612.
7. Zhang, W. et al. (2021). MedRxiv https://doi.org/10.1101/2021.01.18.21249786.
8. Yuan, Y. et al. (2017) Nat. Commun. 8:15092.
9. Walls, A.C. et al. (2010) Cell 180:281.
10. Jiang, S. et al. (2020) Trends. Immunol. https://doi.org/10.1016/j.it.2020.03.007.
11. Ortega, J. T. et al. (2020) EXCLI J. 19:410.
12. Wrapp, D. et al. (2020) Science 367:1260.
13. Tai, W. et al. (2020) Cell. Mol. Immunol. https://doi.org/10.1016/j.it.2020.03.007.
14. Okba, N.M.A. et al. (2020). Emerg. Infect. Dis. https://doi.org/10.3201/eid2607.200841.
15. Wang, X. et al. (2020) https://doi.org/10.1038/s41423-020-0424-9.
16. Wang, K. et al. (2020) ioRxiv https://www.biorxiv.org/content/10.1101/2020.03.14.988345v1.

Bioinformatics

• Uniprot:
  • YP_009724390.1(Llama)