Fig. 1.
SARS N-protein refolding and proteolysis. (A) SARS N-protein produced in M15 cells and purified was refolded by gradual dialysis and the engineered (His)6-tag was removed using Qiagen DAPase as described in Materials and methods. Ten microliters of the protein mixtures were loaded onto 12% SDS–PAGE and stained using Coomassie blue. Lane M, molecular weight markers; lane 1, SARS N-protein in 8 M urea; lane 2, 0.5 M urea; lane 3, 0 M urea; lane 4, 0 M urea; lane 5, 10 min following DAPase addition; lane 6, 20 min following DAPase addition; lane 7, 30 min following DAPase addition. (B) SARS N-protein was produced and refolded without DAPase. Samples were separated on 12% SDS–PAGE and stained with Sypro Ruby Red lane 1, SARS N-protein in 2 M urea; lane 2, 1 M urea; and lane 3, 0.5 M urea.