SDS-PAGE of full length SARS CoV-2 N 5′ 6X-HIS and N-terminal domain with SR region(NTD-SR) 5′ 6X-HIS, produced in E. coli, and purified through HIS spin-columns. Two E. coli clones were grown and induced for 2 hours with IPTG, either at room temperature or at 37C. Full length SARS CoV-2 N is highly expressed expressed as a 50 kDa polypeptide in cultures induced at 37C (lanes 3, 5), but produced only trace amounts of protein at room temperature (lanes 2, 4). A 23 kDa NTD-SR fragment was highly expressed and purified from cultures induced and grown at 37C (lanes 7, 9). Cultures induced at RT produced only trace amounts of protein (lanes 6, 8). SDS-PAGE molecular weight marker (lane 1) is shown for size estimation.