What is the explanation of u shaped bands in the low molecular weight region (~5 kDa), while high molecular weight bands appear as straight lines?

I do peptide western blot, with Tricine SDS PAGE, and try to separate 4.7 kDa and 5.1 kDa proteins. I use my own mini gel: 16.5% separating, thin layer of 10%, and 4% stacking gel. I usually run...

01 January 2014 1,627 2 View