Multiple bands on the sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels of proteins due to intermolecular disulfide cross-linking.

Gel electrophoresis has been used extensively as an analytical technique to check the purity and to determine the molecular weight of proteins. Improved levels of detection of proteins by silver staining of the gels have made the technique more sensitive in detecting heterogeneity. We report here some interesting observations about the anomalous behavior of some proteins in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). This report is concerned with the appearance of multiple bands, after silver staining, on the SDS-PAGE gels of proteins which are shown by HPLC to be homogeneous. We also show the reasons for the appearance of bands that originate from 2-mercaptoethanol itself.