Description：Recombinant COVID-19 S1 protein is produced by our Mammalian expression system and the target gene encoding Cys15-Arg685 (A67V, HV69-70del, T95I, G142D, VYY143-145del, N211del, L212I, ins214EPE, G339D, S371L, S373P, S375F, K417N, N440K, G446S, S477N, T478K, E484A, Q493R, G496S, Q498R, N501Y, Y505H, T547K, D614G, H655Y, N679K, P681H) is expressed with a 10His tag at the C-terminus. The mutations were identified in the COVID-19 variant (known as Omicron/B.1.1.529 lineage) which emerged in South Africa.Form：Liquid in a 0.2 μm filtered solution of PBS, pH 7.4.Alternative Names：S1 protein; SARS-CoV-2 S1 protein; coronavirus S1 Protein; cov S1 Protein Entrez Gene (Human)： 43740568; SwissProt (Human)： P0DTC2; Purity：Greater than 95% as determined by reducing SDS-PAGE.Directions for Use：Please minimize freeze-thaw cycles.Quality Control：Endotoxin: Less than 0.1 ng/µg (1 IEU/µg) as determined by LAL test.Storage/Stability：Store it at -20°C to -80°C for one year. It is recommended that the protein be aliquoted for optimal storage. Avoid repeated freeze-thaw cycles.

• 
  Greater than 95% as determined by reducing SDS-PAGE.
• 
  Loaded Human ACE-2 on Protein A Biosensor, can bind Recombinant COVID-19 S1 Protein (Omicron, B.1.1.529) with an affinity constant of 11.9 nM as determined in bioactivity assay.
• 
  Loaded Anti-COVID-19 S1 mAb on Protein A Biosensor, can bind Recombinant COVID-19 S1 Protein (Omicron, B.1.1.529) with an affinity constant of 1 uM as determined in bioactivity assay.