Recombinant SARS-CoV-2 Spike Glycoprotein

What it means: Target is the identity of the recombinant protein on this page. The target listed here is SARS-CoV-2 Spike Glycoprotein.

How to interpret here: Use SARS-CoV-2 Spike Glycoprotein to confirm you are ordering the correct antigen/standard for your assay or binding study. The sequence origin is listed as Coronavirus—this helps you match the right organism/strain (important for cross-reactivity and epitope differences). The expressed region is aa 16-1213, so you can check whether your epitope/domain of interest is included. The expression system is HEK293 cells, which can affect folding and post‑translational modifications. The protein carries C-terminal His-Avi Tag, which can be useful for purification/immobilization but may affect some functional or antibody-binding assays. The listed molecular weight is 180 kDa, which helps you verify the band size on SDS‑PAGE/Western blot. Choose this when the target name, origin, region, and expression system match your intended application; consider another construct if you need a different domain, a tag‑free version, or a mammalian/insect-expressed protein for native PTMs.

Why it matters for buying:

• Assay relevance: Different isoforms/construct regions can change binding to antibodies, receptors, or aptamers.
• Reproducibility: Using a defined construct (region + tag + expression system) helps you reproduce results across batches and publications.
• Downstream fit: Purity and formulation influence background signal and stability in immunoassays and surface-immobilization experiments.

Helpful selection notes for this listing:

• Database cross-check: The UniProt accession is P0DTC2—use it to align sequence/domain annotations with your experimental plan.
• Synonyms: Spike glycoprotein, S glycoprotein.

Practical guidance:

• Confirm the region: Map your antibody epitope or functional domain to the expressed region before ordering for a critical assay.
• Plan controls: Include a negative control protein and, when possible, a known-binding antibody/ligand to confirm activity/binding on arrival.
• Check purity expectations: If you are using the protein as an ELISA standard or for sensitive binding, higher purity and low endotoxin can reduce background and non-specific effects.

What to watch out for:

• Tag effects: Tags can introduce extra epitopes or steric effects; if your assay is tag-sensitive, consider tag-free options or ensure the tag location is compatible.
• Expression-system differences: Bacterial expression typically lacks glycosylation and some native PTMs—this can change binding for PTM-dependent antibodies or receptors.
• Construct mismatch: A protein fragment may not behave like full-length protein in functional assays.
• Purity context: This listing notes purity as Greater than 90% as determined by SDS-PAGE.; remaining impurities can affect low-signal assays—pilot test at working concentrations.

What it means: Species refers to the organism the protein sequence/antigen is derived from. The value on this page is Coronavirus.

How to interpret here: Use Coronavirus to decide whether the protein matches the biology you’re studying (and the antibodies/ligands you plan to use). This listing is for SARS-CoV-2 Spike Glycoprotein derived from Coronavirus. Choose this when your binding reagents are expected to recognize that organism’s sequence; validate if you intend to use it to test cross-reactivity across species/strains.

Why it matters for buying:

• Epitope differences: Even small sequence changes across species/strains can change antibody binding.
• Assay controls: The origin helps you select appropriate positive controls and interpret unexpected binding.
• Translatability: If you’re modeling a human assay with a non-human protein, treat results as “comparative” and validate with the human ortholog when needed.

Practical guidance:

• Match your reagents: Check your antibody datasheet (immunogen/epitope) against the species/strain shown here.
• Use orthologs strategically: For cross-reactivity studies, test a panel of ortholog proteins under identical conditions.
• Document the construct: Record species + region + expression system in methods to support reproducibility.

What to watch out for:

• Assuming “species” equals expression host: Species here describes sequence origin, not the expression host (see Expression system).
• Viral/bacterial targets: For pathogen proteins, sequence variants can differ—confirm the exact region/strain coverage if critical.

What it means: Expression Region indicates which portion of the protein sequence is expressed/purified (full-length vs fragment). The region listed here is aa 16-1213.

How to interpret here: Use aa 16-1213 to confirm your epitope/domain of interest is included. This listing is for SARS-CoV-2 Spike Glycoprotein covering aa 16-1213. Choose this when the construct matches your assay design (antibody epitope mapping, receptor binding, enzymatic domain testing); consider a different region if you need full-length protein or a specific domain not covered.

Why it matters for buying:

• Epitope inclusion: Antibodies raised against one domain may not bind a fragment missing that region.
• Function vs binding: Many functional assays require correct domain architecture; fragments may bind but not function (or vice versa).
• Background reduction: Fragments can reduce non-specific interactions compared with full-length proteins in some assays.

Practical guidance:

• Map your epitope: If you know the epitope (aa range or domain), confirm it overlaps with the expressed region.
• Confirm expected size: Use the region and molecular weight (if provided) to verify band size on SDS-PAGE/Western.
• Plan orthogonal validation: For critical decisions, confirm binding/function with a second method (e.g., Western, BLI/SPR, activity assay).

What to watch out for:

• Signal peptide/transmembrane regions: Truncated constructs often remove these; that’s normal but may change conformation and binding.
• PTM-dependent epitopes: If your antibody recognizes a glycosylated epitope, a bacterial fragment may not reproduce it.

What it means: Expression system is the host used to produce the recombinant protein. The expression system listed here is HEK293 cells.

How to interpret here: Use HEK293 cells to predict folding and post‑translational modifications (PTMs) and to anticipate handling/validation needs. For SARS-CoV-2 Spike Glycoprotein, choose the expression system that best matches the biology you need (e.g., native-like PTMs vs rapid bacterial production). Choose this when the expression host is compatible with your assay; consider mammalian/insect expression if native glycosylation, disulfide formation, or complex folding is critical.

Why it matters for buying:

• PTM and conformation: Expression host influences glycosylation, disulfide bonding, and folding—key for receptor binding and many antibodies.
• Assay performance: Host-related impurities (and endotoxin for bacterial systems) can increase background or affect cell-based work.
• Reproducibility: Using the same host across experiments reduces variability when comparing binding/activity.

Practical guidance:

• Match the host to your question: For immunoassay standards or binding assays, confirm that the host provides the epitope/conformation you need.
• Validate early: Run a small pilot with your antibody/ligand to confirm binding before scaling up.

What to watch out for:

• Glycosylation-sensitive antibodies: A lack of glycosylation can reduce binding for some epitopes.
• Aggregation: Some recombinant proteins aggregate depending on host and buffer—check solubility after reconstitution and store as recommended.
• Interpreting “activity”: Host choice can strongly affect activity; confirm that “activity” is actually provided/validated if you need it.

What it means: Tag describes tags or conjugated features on the recombinant protein (often used for purification, detection, or immobilization). The conjugate/tag listed here is C-terminal His-Avi Tag.

How to interpret here: Use C-terminal His-Avi Tag to decide how you will capture, detect, or orient the protein in your workflow. Common affinity tags can simplify purification and surface immobilization (e.g., Ni-NTA for His-tag), but the tag can also affect binding in some assays. Choose this when the tag supports your downstream method; consider tag-free or alternate tags if your assay is tag-sensitive or if you need native termini.

Why it matters for buying:

• Workflow integration: Tags determine how easily you can purify, immobilize, or detect the protein.
• Assay interference risk: Tags can introduce extra epitopes or steric effects that change antibody/receptor binding.
• Orientation control: For surface binding (ELISA coating, BLI/SPR), tag-based capture can improve reproducibility versus passive adsorption.

Practical guidance:

• Plan capture strategy: If you want consistent orientation, use tag-capture surfaces rather than random adsorption when possible.
• Check tag location: N- vs C-terminal tags can affect different binding sites; confirm whether your binding region overlaps the tag end.
• Control for tag: Include a tag-only or unrelated His-tagged protein control to detect tag-driven background binding.

What to watch out for:

• Anti-tag antibodies: If your assay uses anti-tag reagents, ensure they do not cross-react with other components in your system.
• Protease cleavage assumptions: Do not assume tags are cleavable unless explicitly stated in the datasheet.
• Immobilization density: Overloading tag-capture surfaces can cause steric crowding and reduce apparent binding.

What it means: Form describes the physical state the protein is supplied in. The form listed here is Lyophilized powder.

How to interpret here: Use Lyophilized powder to plan reconstitution, aliquoting, and storage. Lyophilized proteins typically require careful reconstitution (gentle mixing) and benefit from aliquoting after reconstitution to avoid repeated freeze–thaw. The formulation/buffer is listed in the dataset—review it to ensure compatibility with your downstream assay (e.g., immobilization chemistry or enzymatic activity). Choose this when the supplied form and buffer fit your workflow; plan buffer exchange if your application is sensitive to salts, stabilizers, or carrier components.

Why it matters for buying:

• Stability: Form and excipients affect long-term stability and shipping tolerance.
• Ease of use: Lyophilized powder is convenient for storage but requires correct reconstitution to avoid loss of activity/binding.
• Assay compatibility: Buffer components (e.g., trehalose, salts) can influence coating efficiency, immobilization, and background.

Practical guidance:

• Formulation listed: Lyophilized from a 0.2 μm filtered solution of 10 mM Hepes, 150 mM NaCl with 5% trehalose, pH 7.4.
• Reconstitution note: Centrifuge the vial before opening, reconstitute in sterile distilled water to a concentration of 0.1-1 mg/ml by gently pipetting 2-3 times, don't vortex.
• Storage guidance: The lyophilized protein is stable at -20 °C for up to 1 year. For extended storage, it is recommended to further dilute in working aliquots after reconstitution. The protein solution is stable at ≤ -20 °C for 3 months, or 2-7 days at 2-8 °C under sterile conditions.Avoid repeated freeze/thaw cycle.

What to watch out for:

• Solubility: Some proteins reconstitute slowly; allow time and use gentle mixing to avoid aggregation.
• Buffer mismatch: If you need a specific buffer (e.g., for activity assays), consider buffer exchange after reconstitution.
• Concentration accuracy: After reconstitution, verify concentration if quantitative work is sensitive to dosing (e.g., standards, kinetics).

What it means: Purity describes how clean the protein preparation is and how it was assessed. The purity statement on this page is Greater than 90% as determined by SDS-PAGE..

How to interpret here: Use Greater than 90% as determined by SDS-PAGE. to judge whether the protein is suitable for your application’s sensitivity. Choose this when the stated purity aligns with your assay needs; consider higher-purity/low-endotoxin options for cell-based work, structural studies, or low-background quantitative assays.

Why it matters for buying:

• Background and specificity: Impurities can increase non-specific binding and background signal in ELISA and surface binding assays.
• Reproducibility: Higher purity generally reduces lot-to-lot variability in sensitive applications.
• Downstream compatibility: For cell culture or immune assays, contaminants (including endotoxin) can change biology independent of the target protein.

Practical guidance:

• Match purity to use-case: For immunogen use or basic binding screens, moderate purity may be acceptable; for quantitative standards and kinetics, cleaner prep reduces noise.
• Run a quick QC: Verify band size and major species by SDS‑PAGE/Western on arrival if the application is critical.
• Consider buffer effects: Some “purity” statements reflect gel-based estimates; if your assay is extremely sensitive, confirm by your own QC where possible.

What to watch out for:

• Purity method differences: SDS‑PAGE estimates and chromatographic purity can differ; interpret the statement as guidance, not an absolute guarantee of a single species.
• Aggregate/fragment species: Purity does not always report aggregation; check solubility and run conditions that reveal aggregates if needed.
• Cell-based assays: If you see unexpected cytokine-like responses, consider endotoxin/contaminants as a confounder and validate with controls.