Gloria,
Why don't you introduce TEV-cleavage site? You can clone it between His- and sumo-protein_of_interest (if you want co-crystallise sumo with your protein) or between His-sumo and protein_of_interest (if you want to crystallise your protein only).
Vitali
My fellow crystallographers,
We are thinking the SUMO/His vectors would be nice to have in the lab
aresenal... but. The stumbling block is that the protease needed for
cleavage is very expensive at crystallography scale. SUMO(ULP-1)
protease costs ~$700/mg fusion protein. It would not be a problem
for labs using micrograms of protein, but is prohibitive at our level
of protein purification.
Has anyone found a way around this? Your pal, Gloria