Free-solution electrophoresis of proteins in an improved density gradient column and by capillary electrophoresis

Abstract

The electrophoretic mobilities of bovine serum albumin, β-lactoglobulin A and B, α-lactalbumin and myoglobin were measured in free solution using an improved version of the Boltz-Todd vertical density-gradient electrophoresis column. Dialysis membranes were used for the isolation of the side-arm electrodes from the column and large-volume electrode containers were connected to each other by a circulating buffer loop. The improvements increased reliability, facilitated removal of electrode gas, prevented proteins from contacting electrodes and allowed the use of low conductivity buffers without ion depletion. A low conductivity buffer (Tris-glycine) allows the use of high fields for rapid separations. The apparatus is modular and allows easy modification of column dimensions. We have also measured the electrophoretic mobility of these proteins in a coated capillary in the absence of significant electroosmotic flow.