A Facile System for Processing Polyacrylamide Disc Gels Following Electrophoresis Polyacrylamide gel electrophoresis is one of the most widely employed modern biochemical techniques. When used with sodium dodecyl sulfate for example i t rapidly gives quite accurate molecular weight values. The combination of detailed published protocols1together with the modest equipment required to ohtain research quality results makes this methodology quite attractive for instructional purposes. The one drawback is the gel processing which follows the electropharesis. Most often the gels are placed in individual tubes and the solutions must be changed frequently over a period of days for fixing, staining, washing, and destaining. This is time-consuming and tedious. The following apparatus is simple t o use, easy to make, and very low in cost. A number of plastic test tubes (e.g., 16 X 125 mm Falcon Plastic) are pierced with a red hot nail enough times to produce approximately 20 holes distributed along the length of the tuhe. After electrophoresis eaeh gel is marked a t the tracking dye and placed in a plastic tube. Don't put a hole in the bottom of the tube since the little devils are wont to slither out. The gels need never be touched after this and can he observed, washed, etc., with no chance of damage. The tuhe is corked (the cork carries the gel number designation) and placed in a 4-1 beaker with the first processing solution; the tuhe will float. A magnetic stirrer and stir bar complete the apparatus. The stirring action moves the tubes through the solution and leads to a very efficient exchange of liquid next t o the gel. This, coupled with the large solution volume accounts for extremely effective processing and only one volume of solution is required a t eaeh step. For the destaining step we hang a cloth hag of charcoal in the beaker to adsorb dye (ewmassie brilliant blue) although an ion exchange resin may also be used. If a separate staining step is used this can be done in a 400-ml beaker to conserve stain, and the tubes washed under the tap before transfer to the next solution.
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Maizel, J. V.,Meth. In. Virology, 5,179 (1971).
Dartmouth College Hanover, New Hampshire 03755
644 / Journal of Chemical Education
P a u l M. Horowitz
