A sodium dodecyl sulfate--polyacrylamide gel electrophoresis system that separates peptides and proteins in the molecular weight range of 2500 to 90,000.

A discontinuous sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis system is described which provides superior resolution of polypeptides with molecular weights from approximately 2500 to 90,000. The system utilizes a relatively low-mobility acetate ion in the stacking gel and high-mobility strong anions, sulfate and chloride, as leading and trailing ions in the separating gel. The entire system is run at pH 7.8. The separating gel contains 8 M urea, and can be used at acrylamide concentrations from 5 to 18%, all with 5% crosslinker concentrations. Using a number of protein standards, the calibration curves obtained with this system are linear over the molecular weight range from 2500 to 90,000, regardless of acrylamide concentration. These studies indicate that by providing good resolution of small peptides, this system greatly extends the utility of one-dimensional peptide mapping techniques.