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Recombinant SARS-CoV-2 spike RBD-Fc, and biotinylated His-tag and Fc-fused spike RBD are available.
Price/availability/specifications subject to change without notice. Unless otherwise indicated, our catalog and customized products are for research use only and not intended for human or animal diagnostic or therapeutic use.
Phone: 1-617-401-8149
Fax: 1-617-606-5019
Email: message@sydlabs.com
Or leave a message with a formal purchase
order (PO) Or credit card.
Source: Recombinant SARS-CoV-2 Spike RBD protein (S protein RBD, S1 RBD, Arg319-Asn532) was expressed in mammalian cells with a His tag and Avi at the C-terminus.
Accession: QHD43416.1
Predicted molecular mass: 27 kDa. Due to glycosylation, the recombinant SARS-CoV-2 Spike RBD protein migrates to 36-40 kDa based on the Bis-Tris PAGE result.
Endotoxin: Less than 1 EU per ug by the LAL method.
Formulation: The recombinant SARS-CoV-2 Spike RBD-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 RBD-His-Avi protein is shipped at ambient temperature. 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.
Questions and answers:
Question: Are the spike protein RBDs between SARS-CoV-2 and SARS-CoV highly conserved? How about their epitope sequences?
Answer: The spike protein RBD from SARS-CoV-2 shows about 74% similarity with the SARS-CoV homologue. Binding test results of SARS-CoV S1 RBD monoclonal antibodies against SARS-CoV-2 spike S1 subunit RBD suggests that difference between the RBD epitope sequences and post-translational modification may play important role in host immune response. It is better to use the SARS-CoV-2 spike S1 subunit or S1 RBD and their specific antibodies in manufacturing of SARS-CoV-2 IgG/IgM antibody test kits and antigen test kits.
Question: Is there false positive result if the spike S1 or S1 RBD-based SARS-CoV-2 IgG/IgM antibody rapid test kit is used for clinical diagnostic test?
Answer: Yes though the possibility is significantly lower than nucleocapsid-based test kit. The cross-reactivity possibility with other coronavirus(es) has to be tested and excluded.
Question: Then why are the nucleocapsid-based SARS-CoV-2 IgG/IgM antibody test kits still widely used?
Answer: The nucleocapsid protein is the most abundant protein in SARS-CoV-2 and is highly immunogenic, it is often used as a marker in diagnostic immunoassays in the ELISA and colloidal gold-based rapid test kits. Its sensitivity is high though crossactivity is also high.
Question: Do you have discount if we place bulk order of the recombinant SARS-CoV-2 (2019-nCoV) spike protein RBD-His-Avi for IVD material?
Answer: Sure. We also sell monoclonal human and rabbit spike RBD antibodies as well as alpaca S1 RBD VHH antibodies as research reagent and IVD materials.
Biotinylated Recombinant SARS-CoV-2 Spike RBD-His-Avi
Recombinant SARS-CoV-2 Spike RBD-His-Avi
Recombinant SARS-CoV-2 Spike RBD-Fc-Avi
Biotinylated Recombinant SARS-CoV-2 Spike S1-His-Avi Protein
Recombinant SARS-CoV-2 Spike S1-His-Avi Protein
Recombinant SARS-CoV-2 Spike S1-Fc-Avi Protein
Recombinant SARS-CoV-2 Spike S-Fc-Avi Protein
Biotinylated Recombinant SARS Spike RBD-His-Avi
Recombinant SARS Spike RBD-His-Avi
Recombinant SARS-CoV-2 Nucleocapsid Protein-His-Avi
Biotinylated Recombinant Human ACE2-His-Avi Protein
Recombinant Human ACE2-His-Avi Protein
Recombinant Human ACE2-Fc-Avi Protein
To check more Syd Labs SARS-CoV-2 (2019-nCoV) Antigen and Antibody Reagents and Discovery Services
Background
The S1 subunit and its receptor binding domain (RBD) of the SARS-CoV-2 (2019-nCoV) spike (S) glycoprotein 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. There are two subunits, S1 and S2, in the SARS-CoV-2 spike (S) glycoprotein. The S1 subunit, the N-terminal 14–685 amino acids of the S protein, contains N-terminal domain (NTD), receptor binding domain (RBD, 331-524), and receptor binding motif (RBM). The SARS-CoV and SARS-CoV-2 spike proteins mediate viral entry into host cells by binding to a host receptor, angiotensin-converting enzyme 2 (ACE2), through the receptor-binding domain (RBD), and then fusing the viral and host membranes through the S2 subunit. The ACE2-binding affinity of the Spike RBD of SARS-CoV-2 is 10- to 20-fold higher than that of SARS-CoV.
The SARS-CoV-2 spike RBD has become a popular target of antibodies for diagnostics tests. It is critical to use an active protein with natural conformation and post-translational modification as the antigen, even for the SARS-CoV-2 IgM/IgG test kit (S protein) which is popularly used to check people already carrying immune response against the COVID-19 virus. Thus, the spike RBD should be expressed in mammalian cells, such as HEK 293 and CHO cells.
The amino-acid sequence identity is around 74% between the RBDs in the SARS-CoV and SARS-CoV-2 spike proteins, similar to the 77% identity between the whole spike proteins of SARS-CoV and SARS-CoV-2. Such a high degree of sequence similarity raises the possibility that cross-reactive epitopes may exist. Although the SARS-CoV spike RBD polyclonal antibodies can recognize both viruses, only one out of a few published spike RBD monoclonal antibodies neutralizing SARS-CoV binds to SARS-CoV-2 spike RBD. Out of the 28 residues in the epitope of the spike RBD monoclonal antibody, only 4 residues (86%) in SARS-CoV-2 are different from SARS-CoV. However, the spike RBD mAb binds to SARS-CoV spike RBD (Kd = 1 nM) with a much higher affinity than to SARS-CoV-2 spike RBD (Kd = 115 nM, or 6.3 nM measured by another lab).
Recombinant SARS-CoV-2 spike RBD-Fc and RBD-His proteins are both available with an Avi site, which is for biotinylation. Biotinylated recombinant SARS-CoV-2 spike RBD-His and RBD-Fc proteins are also available. Please ask for a quote if you need SARS-CoV-2 spike protein RBD mutants or a protein with different modification or components.
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