Practice question

Stacking gel with low acrylamide percentage and pH 6.8 Tris-HCl concentrates dilute protein samples into extremely sharp zones before resolution through isotachophoresis, also called Kohlrausch discontinuity. Chloride from Tris-HCl acts as highly mobile leading ion, while glycine at this pH is predominantly zwitterionic with low mobility as trailing ion. Proteins possess intermediate mobility and become sandwiched between them, stacking into narrow bands of micrometer thickness. Upon entering resolving gel at pH 8.8, glycine becomes fully anionic, overtakes proteins, and sieving separation begins. This ensures superior band sharpness.