22-S2SOM1-TCg-F

SARS-CoV-2 Spike glycoprotein Omicron (B.1.1.529) variant trimeric ectodomain from mammalian CHO cells, frozen

Description: SARS-CoV-2 recombinant Spike Omicron variant (SCoV2-rSο) glycoprotein ectodomain expressed as secreted trimeric protein in mammalian (hamster) CHO cells. It contains thirty-four mutations in comparison to the reference SARS-CoV-2 Spike protein sequence (UniProtKB accession number: P0DTC2 (SPIKE_SARS2)): A67V, HV69/70del, T95I, G142D, VYY143-145del, N211I, L212del, ins214EPE, G339D, S371L, S373P, S375F, K417N, N440K, G446S, S477N, T478K, E484A, Q493R, G496S, Q498R, N501Y, Y505H, T547K, D614G, H655Y, N679K, P681H, N764K, D796Y, N856K, Q954H, N969K, L981F; expressed ectodomain includes amino acids (aa) 1-1208. Whole expression construct includes: full-length SCoV2-S ectodomain (aa 1 – 1208) w/o transmembrane and cytoplasmic aa, furin cleavage site “RRAR” mutated to “GSAS”, C-terminal GSN4 trimerization motif fused to protein sequence, then follows thrombin cleavage site, Strep-tag II and His6-tag. Two mutations (K986P and V987P) were introduced into SCoV2-S sequence to stabilize the trimer in the pre-fusion conformation. SCoV2-rSο glycoprotein was purified from culture medium under native (non-denaturing) conditions using convenient chromatographic techniques. Then it was dialyzed against PBS, filter-sterilized, aliquoted and frozen for storage.

Form: Frozen liquid in PBS (pH 7.4) with 0.05% of Tween 20.

Storage: The product is shipped with dry ice (shipment cost to Europe: 160 €). Store at -80°C for the long term. After thawing may be stored for short-term at 4°C (stable at least 2 weeks at this temperature). Avoid repeated freeze/thaw cycles.

Concentration: 1.0 mg/ml.

Purity: >90 % including truncated forms of the same protein, as determined by SDS-PAGE and Western blot.

Image: SDS-PAGE showing SCoV2-rSο product 22-S2SOM1-TCg-F at approximately 160 kDa (1, 3 and 5 μg/lane).

Applications (tested): ELISA, other immunoassays, biochemical and biophysical analyses, electrophoretic analysis, Western blotting.

Quality: According to the expressed construct, purified SCoV2-rSο protein should be trimer in the stabilized prefusion conformation. Full-length trimeric protein enables detection of more antibodies against SCoV2-S, than shorter protein constructs (e.g., RBD or S1). It provides a tool to develop highly sensitive immunoassays. This product 22-S2SOM1-TCg-F showed similar sensitivity and specificity with COVID-19 positive and negative patient sera in ELISA, as initial sequence SCoV2-rS protein construct (see product 20-S2S-TCg-G information), but quantitative results (reactivity with Covid-19 positive samples) were rather different and strain-specific. Note: a lesser number of individual sera was tested, than with initial sequence SCoV2-rS protein variant.

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Note: Biotinylated form of this product is available under request.