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Recombinant SARS-CoV-2 Spike S1 Protein
BP003054: Recombinant SARS-CoV-2 Spike S1-His-Avi Protein (Spike Protein S1 Subunit)
Source: recombinant SARS-CoV-2 spike protein S1 subunit (Gln14-Arg683) was expressed in mammalian cells with a His tag and Avi at the C-terminus.
Predicted molecular mass: 77.9 kDa. Due to glycosylation, the recombinant SARS-CoV-2 S protein S1 subunit migrates to 110-120 kDa based on the Bis-Tris PAGE result.
Endotoxin: Less than 1 EU per ug by the LAL method.
Activity: Immobilized recombinant SARS-CoV-2 Spike S1-His-Avi protein at 0.5 ug/ml (100 ul/well). Dose response curve for the biotinylated recombinant human ACE2-His fusion protein with the EC50 of 0.2 ug/ml determined by ELISA.
Formulation: The recombinant SARS-CoV-2 Spike S1-His-Avi protein was lyophilized from 0.22 um filtered solution in 20 mM PB (pH 7.4). Normally 5% trehalose is added as protectant before lyophilization.
Purity: > 95% by PAGE under reduced condition, and SEC-HPLC.
Shipping: The recombinant SARS-CoV-2 Spike S1-His-Avi protein is shipped with ice packs. Upon receipt, store it immediately at the temperature recommended below.
Stability & 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.
There are two subunits, S1 and S2, in the SARS-CoV-2 spike (S) glycoprotein which plays the most important roles in viral attachment, fusion and entry, and serves as a target for development of virus entry inhibitors, neutralizing antibodies, and vaccines. The S1 subunit, the N-terminal 14–685 amino acids of S protein, contains N-terminal domain (NTD), receptor binding domain (RBD), and receptor binding motif (RBM). The SARS-CoV and SARS-CoV-2 S proteins mediate viral entry into host cells by binding to a host receptor, angiotensin-converting enzyme 2 (ACE2), through the receptor-binding domain (RBD) in the S1 subunit, and then fusing the viral and host membranes through the S2 subunit.
Please ask for a quote if you need protein mutants or a protein with different modification or components.
To check more Syd Labs SARS-CoV-2 (2019-nCoV) Antigen and Antibody Reagents and Discovery Services
Syd Labs also provide custom antibody discovery services to screen more and better antibodies for therapeutic drugs, diagnostic immunoassays, and research reagents:
SARS-CoV-2-specific human neutralizing monoclonal antibody development service: If a client or collaborator provides PBMC from recovered COVID-19 patients or people with SARS-CoV-2 vaccines, Syd Labs can do single B cell sorting and culturing. We can send out about 70 ul supernatant per well (clonal single B cell) for quick screening. Then you tell us which single B cell clone you like. We sequence the antibody VH/VL and produce the recombinant human monoclonal antibody for your confirmation. The efficiency is much higher than antibody cloning and sequencing immediately after single B cell sorting; of course, the total cost is much lower. A few groups have used the single B cell method without culturing after sorting to identify some neutralizing monoclonal antibodies against the SARS-CoV-2 spike protein, especially its S1 RBD. It remains unknown how good they are to become therapeutic drugs. Using the strategy without culturing, one may screen antibodies from hundreds of single B cells after a lot of efforts; however, one may easily screen antibodies from thousands of cultured single B cells.
SARS-CoV-2 Spike S1 rabbit monoclonal antibody development service: Syd Labs immunized rabbits with SARS-CoV-2 S protein S1 subunit, then did single B cell sorting and culturing. S1 subunit may be better than its RBD as the immunogen. There will be about 70 ul supernatant per well (clonal single B cell). If a client is interested in rabbit monoclonal antibodies against SARS-CoV-2 Spike protein (S protein), we can send you some supernatant for quick screening. Then you tell us which single B cell clone you like. We sequence the antibody VH/VL and produce a recombinant rabbit monoclonal antibody for your confirmation. You can pay for the antibody or the clone.
SARS-CoV-2 spike S1 VHH nanobody development service: Syd Labs will immunize alpaca with SARS-CoV-2 S protein S1 subunit protein, then do single B cell sorting and culturing or construct VHH nanobody phage display libraries. All the process is the same as "SARS-CoV-2 Spike S1 rabbit monoclonal antibody development service". The spike nanobodies may be good candidates for therapeutic drugs alone or by combination with other proteins or antibodies.
To know more about our human, rabbit, and alpaca (camelid) monoclonal antibody development services, please visit:
Questions and Answers:
Question: Is your recombinant spike protein S1 subunit trimer or monomer?
Answer: Different from the spike protein in the virus, the S1 subunit is a monomer.
Question: Do you have SARS-CoV-2 spike protein S1 subunit-based rapid test kit or ELISA kit?
Answer: They are under development.
Question: What is the advantage of spike protein S1 subunit-based immunoassay kits to nucleocapsid-based kits?
Answer: S1 subunit-based immunoassay kits have better specificity.
Question: Is S1 subunit or its RBD a better immunogen for antibody development?
Answer: S1 subunit is better since it is bigger with more potential epitopes possibly better for neutralizing antibody development. Even for RBD, some antibodies binds to RBD but does not block the interaction between RBD and the receptor ACE2.