Size-dependent separation of proteins denatured in SDS by capillary electrophoresis using a replaceable sieving matrix.

The determination of molecular weights by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) is one of the most powerful electrophoretic techniques for protein characterization. A separation media has been developed which allows this type of analysis to be performed in the capillary format. A replaceable polymeric solution rather than a polymerized gel was used as the sieving matrix. This solution allowed for the separation of proteins denatured in SDS in a size-dependent manner as demonstrated by the linear correlation between the proteins' relative migration and the concentration of the sieving matrix (Ferguson plot). The logarithm of the molecular weight of protein standards correlated linearly with the relative mobility of the denatured proteins over the molecular weight range of 14,000 to 205,000. The calculated resolution at half-peak height was such that proteins that differed by as little as 4% in molecular weight would be resolved. Finally, the integrated peak areas at 215 nm were linearly proportional to the mass of the protein injected.