b'Precast vs. handcast gels Choosing the right gel percentage Traditionally, researchers poured their own gels usingIn general, the size of the molecule being separated should standard recipes that are widely available in the proteindictate the acrylamide or agarose percentage you choose. methods literature. Today, more researchers rely on theUse a lower percentage gel to resolve larger molecules convenience and consistency of commercially available,and a higher percentage gel to resolve smaller ones. ready-to-use precast gels. We offer precast gels in aThe exception to this rule is when performing isoelectric variety of percentages, including difficult-to-pour gradientfocusing. Refer to the gel migration charts throughout this gels that provide excellent resolution and that separatechapter to find the gel best suited for your application. proteins over the widest possible range of molecularAs a general rule, molecules should migrate through about weights. Precast gels are also available with several70% of the length of the gel for the best resolution. When different buffer formulations (e.g., Tris-glycine, Tris-acetate,protein molecular weights are wide ranging or unknown, Bis-Tris, and tricine), which are designed to optimize shelfgradient gels are usually the best choice.life, run time, and protein resolution. More importantly, precast polyacrylamide gels eliminate the need to workChoosing a well format and gel thicknesswith acrylamide, which is a known neurotoxin and suspected carcinogen. Two thicknesses (1.0 mm and 1.5 mm) are available for popular gel types. If loading large sample volumes (30 L), However, some scientists need unique gel formulationsa thicker gel (1.5 mm) with fewer wells (e.g., 5-well) may be not available in precast gel formats. In those cases, themore appropriate. Another consideration for large sample gel-pouring process can be made easier by using newer,volumes is choosing a wedge-well format that is found in leak-free handcast systems, such as the Invitrogenour Bolt Bis-Tris Plus or Novex Tris-Glycine gels. When SureCast system, or by using preassembled emptyblotting, remember that proteins will transfer more easily gel cassettes.from a 1.0 mm thick gel than from a 1.5 mm thick gel. We offer most of our polyacrylamide gels in nine different well formats (17-well, 15-well, 12-well, 10-well, 9-well, 5-well, 1-well, 2D/preparative well, IPG well).Wedge-shaped well of Bolt Bis-Tris Plus and Novex Tris-Glycine WedgeWell format gels.Did you knowOver 45 years ago, Ulrich K. Laemmli first published on SDS-PAGE as a method for cleavage analysis of structural proteins in bacteriophage T4.10'