I want a protein of 15kDa but only see a protein of 10Da when its purified - any thoughts?

I am trying to express a 15kDa protein in E.coli strain BL-21 DE3 but when I expressit I get a protein with a molecular weight of 10,700Da. My system is pET-22b with the export tag cut out with...

07 July 2014 5,622 8 View