[18] Slab gel system for the resolution of oligopeptides below molecular weight of 10,000

The systems of polyacrylamide gel electrophoresis that are in current use for the molecular weight determinations of conventional proteins are not well suited for resolving proteins below 10,000. This chapter describes certain modifications of the basic Swank and Munkres procedure that allow the gels to be slab-cast. The method is favorable, particularly for the resolution of small oligopeptides that are between Mr 1500 and 10,000. In preparing the gel, add everything except the SDS, TEMED, and ammonium persulfate to a small beaker; place the beaker in a 50-55° C water bath, and swirl gently until solid material is completely dissolved. After the gel is mounted on the gel apparatus and the buffer added, the sample wells must be washed out thoroughly just before application of the samples. Excess urea must be removed if the gel is to be dried back for autoradiography without prior staining or if it is to be treated for fluorography.