Target Name: SARS-CoV2 Spike RBD Protein, RBD Protein 
Source: SARS-CoV-2 Spike protein (accession number QHD43416.1) RBD domain (Arg319-Phe541) with C-terminus 8xHis tag and an Avi-tag is expressed in HEK293 cells. This protein was site-specifically labeled with Biotin by BirA ligase. The labeling efficiency is greater than 90% by gel shift assay.
Molecular Weight: The 253 amino acid protein has a predicted molecular weight of 28.5 kDa. The protein migrates at approximately 30-40 kDa on SDS-PAGE with DTT-reduced conditions.
Purity: >95% based on SDS-PAGE
Formulation: PBS, 0.22 µm filtered
Vial Size: 25µg, 100µg
Protein Concentration: 25µg size is bottled at 0.2mg/mL concentration. 100 µg size is bottled at lot specific concentration.
Storage and Handling: Quick spin the vial after receiving. An unopened vial can be stored at 4°C for 2 weeks or at -20°C and below for six months. The protein can be further diluted to 0.1 mg/mL with 0.22 µm filtered PBS.  This stock solution should be aliquoted and stored at ≤ -70°C to minimize the freeze/thaw cycles. Carrier proteins such as FBS and BSA need to be added if further dilution is needed.