DNA fragments encoding SARS-CoV-2 Nsp13 residues A5325-G5925 were amplified via PCR and sub-cloned into the pFBD-BirA expression vector. The insert was positioned downstream of the AviTag for in vivo biotinylation and upstream of a HisTag. The resulting plasmid was transformed into DH10Bac™ competent E. coli (Invitrogen) and a recombinant viral bacmid DNA was purified and followed by a recombinant baculovirus generation for baculovirus mediated protein production in Sf9 insect cells. Biotin was added to the medium at a final concentration of 10 μg/mL. Cells were harvested by centrifugation at low speed (2500 rpm for 10 minutes at 4 °C in a Beckman Coulter centrifuge) when cell viability dropped to 70-80%. The cells were resuspended in extraction buffer (20 mM Tris-HCI, pH 7.2, 500 mM NaCl, 5% glycerol, 5 mM Imidazole + 1 ml PI cocktail (Aprotinin, Leupeptin, Pepstatin A, and E-64) and lysed chemically by adding NP40 (final concentration of 0.5%) and 5 µl/L Benzonase Nuclease (in-house) followed by sonication at the frequency of 7.0 kHz (5" on/17" off) for 3 min (Sonicator 3000, Misoni). The crude extract was then clarified by high-speed centrifugation (60 min at 36,000 ×g at 4 ˚C) in a Beckman Coulter centrifuge to remove the cellular debris. The clarified lysate was first sent through a Ni-NTA resin column followed by passage through Gel filtration HiLoadTM 26/600 Superdex (Cytiva) with 50 mM Tris, pH 7.2, 200 mM NaCl, 5% glycerol, 0.5 mM TCEP to enrich nsp13_SARS2 to 95% purity. Following the identification of the protein eluting fraction and purity using SDS-PAGE gels, and mass confirmation, the fractions were pooled, concentrated, snap-frozen, and stored at -80 0 C until use. Protein mass was confirmed by LC-MS.