SDS-PAGE Spacer Buffer [4x] (pH 6.8)

SDS-PAGE Gel Spacer Buffer (pH 6.8) is used in the preparation of stacking gel mix while performing SDS-PAGE. It is used for the separation of proteins through electrophoresis and it is based on the fact that charged molecules will migrate through a matrix upon application of an electrical field. The matrix for protein electrophoresis separation is polyacrylamide.

SDS-PAGE uses two types of buffer systems: the continuous buffer system and the discontinuous buffer system. In the continuous buffer system, the pH of the gel matrix remains constant throughout the separation. In contrast, the discontinuous buffer system consists of a narrow layer of stacking gel (of large pore size and acidic pH, 6.8) above the main separating gel matrix of alkaline pH.

The stacking gel contains chloride ions, which migrate more quickly through the gel than the protein sample, while the electrophoresis buffer contains glycine ions, which migrate more slowly. The protein molecules are trapped in a sharp band between these ions. The stacking gel concentrates the protein sample before entering the separating gel which enhances the resolution. SDS-PAGE with a discontinuous buffer system is the most popular electrophoresis technique used to analyze polypeptides.

The buffer consists Tris Base & SDS in recommended concentrations at pH 6.8. The buffer is supplied in 4x concentrate and should be diluted prior to use in electrophoresis.