Why is the molecular weight of SARS-CoV-2 Spike (trimeric) (16-1208) Recombinant Protein (8xHis-Tag) #65444 136 kDa under both reduced and non-reduced conditions?

Even without DTT, non-reducing conditions are harsh on protein structure. In-house, samples are heated to 95°C for 5 min in the presence of SDS, so the protein (including the trimerization domain) is fully denatured. This results in a loss of its ability to trimerize. It is possible a native gel would run closer to the trimeric molecular weight. We have also run SEC-HPLC on this product to confirm that we observe the expected MW of a trimeric protein when it is in solution. 

Last updated: February 26, 2024