Recombinant SARS-CoV-2 S-trimer Protein (His Tag)

What it means: Mammalian (HEK293) — this protein was produced using a Mammalian (HEK293) recombinant expression system, determining its post-translational modification profile, folding characteristics, and suitability for specific research applications.

Why it matters:

• Mammalian systems (HEK293) support human-like glycosylation and disulfide bond formation — important for cytokines, immune checkpoint proteins, and receptor-binding assays requiring native-like structure.
• Baculovirus/insect cell systems offer high-yield expression with partial glycosylation; E. coli provides non-glycosylated protein at scale; Yeast (Pichia) is used for selected glycoproteins requiring secreted expression.

How to interpret here: This protein was expressed in Mammalian (HEK293). For assays sensitive to glycosylation patterns (receptor binding, cell-based activity), verify the expression system is appropriate for your experimental requirements.

What it means: > 95% as determined by reducing SDS-PAGE. — purity was assessed by reducing SDS-PAGE to confirm the proportion of the preparation that is the correctly-sized target protein.

Why it matters:

• High purity minimises contaminant-derived background in sensitive assays such as SPR/BLI, ELISA, enzyme kinetics, and cell-based activity studies.
• Consistent lot-to-lot purity is essential for reproducibility in quantitative dose-response experiments.

How to interpret here: > 95% as determined by reducing SDS-PAGE. by SDS-PAGE confirms the preparation meets release specifications. Lot-specific gel images are available on the Certificate of Analysis. Contact technical support if ultra-high purity (>98%) is required for biophysical measurements.

What it means: LAL-tested, <1.0 EU/µg — endotoxin content was measured by the Limulus Amebocyte Lysate (LAL) chromogenic assay, confirming the preparation is below the <1.0 EU per µg release specification.

Why it matters:

• Endotoxin contamination activates NF-κB and innate immune pathways in cultured cells, causing artefactual cytokine induction that masks true protein bioactivity and confounds functional assay results.
• LAL-tested proteins are required for cell stimulation experiments, primary cell culture, and any assay measuring immune activation or cytokine secretion.

How to interpret here: <1.0 EU/µg confirms suitability for cell-based assays and cell culture applications. Lot-specific endotoxin data is available on the Certificate of Analysis.

What it means: C-His — this affinity tag is fused to the recombinant protein to facilitate chromatographic purification and enables tag-specific antibody detection in downstream assays.

Why it matters:

• His-tag enables one-step IMAC purification; GST-tag enables glutathione-affinity purification with improved solubility for some proteins; Fc-tag enables protein A/G purification and extends half-life in binding assays.
• The position (N- or C-terminal) of the tag may affect folding, activity, and binding domain accessibility — consider this when designing binding or functional assays.

How to interpret here: The C-His tag is available for detection using anti-His, anti-GST, or anti-Fc antibodies in ELISA, pull-down, or flow-based assays. Verify the tag does not interfere with the target domain in your assay system.

What it means: 12 months — this is the expected product shelf life when stored under recommended conditions as stated on the product label and Certificate of Analysis.

Why it matters:

• Knowing the shelf life enables planning for long-running experiments and verifying whether the remaining lot will be valid for the full duration of a project or assay campaign.
• Shelf life assumes recommended storage conditions (−20 to −80°C for lyophilized; −20°C for liquid) and minimal freeze-thaw cycles of the bulk stock.

How to interpret here: 12 months from the date of receipt under recommended storage. Working aliquots from reconstituted lyophilized protein are typically stable for 3 months at −80°C. Check the expiry date on the product vial before use.

What it means: This protein has been tested and confirmed for functional activity. Activity summary: Loaded Human ACE-2-Fc on Protein A Biosensor, can bind 2019-nCoV S-trimer Protein-His with an affinity constant of 0.125 nM as determined in BLI assay

Why it matters:

• Functional activity validation confirms the protein is correctly folded and biologically active, making it suitable for bioassays, receptor binding studies, and enzyme kinetics in addition to structural or antibody applications.
• Specific activity data (e.g. ED50, enzyme kinetics, EC50 values) provides a quantitative basis for comparing lots and designing dose-response experiments.

How to interpret here: Lot-specific bioactivity data is available on the Certificate of Analysis. Contact technical support for guidance on optimising the functional assay for your experimental conditions.

What it means: UniProt accession P0DTC2 is the stable, unique identifier for this protein in the Universal Protein Resource (UniProtKB) database.

Why it matters:

• The UniProt entry provides the canonical sequence, known isoforms, PTM sites, disease associations, and curated literature — essential for experimental design and data interpretation.
• Cross-referencing results to UniProt enables standardised reporting and integration with other databases (PDB, STRING, OMIM, Ensembl).

How to interpret here: Use accession P0DTC2 at uniprot.org to retrieve the full sequence, confirm the expressed region covered by this product, verify isoform representation, and identify known functional domains and active sites.