Behavior of unreduced polymeric and monomdric immunoglobulins in sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Investigation of the electrophoretic behavior, in SDS-polyacrylamide and SDS-polyacrylamide-agarose gels, of IgMs and low mol. wt. Igs from four classes of vertebrates, as well as fragments derived from them, was carried out. A clear but unexpected straight-line relationship was observed for all Igs (and fragments) tested when relative mobility was plotted against log mol. wt for the unreduced molecules. Aberrant behavior of the low mol. wt Ig of Bufo marinus was shown to be due to the complete dissociation of the molecule into free light chains and heavy-chain dimers, in the presence of SDS.