PAGE proteolysis? help!!
TLDR I ran a gel for a his tagged protein I'm expressing in E. coli and I'm really not sure what to make of the smeared band I observe where I expect to see my protein, looks to me like proteolysis or (hopefully, tbh) just a gel running issue?
My target (his tag, SUMO for tag cleavage, "Rex3" is a 20AA IDR of interest, and 2x nanoluciferase) ought to be 52.2 kDa, and there's clearly something around that range but it doesn't look like it's coming out in one piece. My first (terrifying) thought was proteolysis despite the inhibitors (Roche cOmplete, EDTA-free) in the lysis buffer, but I also wonder if it could just be overloaded in a funky way or running weird or even modified in bacteria (looked to me like ubiquitination almost, if it wasn't e coli). Any help much appreciated!!