[8] Use of Gel Electrophoresis to Characterize Multimolecular Aggregates

The procedures for identifying, isolating, characterizing, and quantitating multimolecular complexes are electrophoresis in gels. Electrophoresis in multisample slab gels can be used to detect and quantitate the particles in hundreds of samples simultaneously subjected to electrophoresis in a single gel bed. Agarose gels appear to have the best handling characteristics and range of pore sizes for the electrophoresis of multimolecular complexes with radii above 5-10 nm—i.e., almost all viruses. To characterize such complexes, the techniques presented in this chapter are designed for determining electrophoretic mobility (μ) in agarose gels as a function of agarose percentage (A) in the gel, and the following data can be calculated: (1) μ in the absence of a gel (μ_o; directly proportional to the average electrical surface charge density), and (2) outer radius (R) of spherical particles (or effective R of nonspherical particles). Although agarose gels are used with the procedures described in this chapter, some of these procedures have potential for use (possibly with modification) with other types of gels.