I am currently working on beta-endorphin (3.5 kDa). I made a 10% tricine gel with the modified method (Haider 2012) which works quite well for my molecular weight marker (GE Healthcare) and the recombinant beta-endorphin (in 0.1 % acetic acid). But my samples extracted in RIPA buffer or different tris based-buffer migrate only until 12 kDa.
Can you offer advice on a more appropriate extraction buffer for separation in a tricine gel ?