Charge shift electrophoresis: simple method for distinguishing between amphiphilic and hydrophilic proteins in detergent solution.

Seventeen hydrophilic proteins and five amphiphilic membrane proteins were subjected to agarose gel electrophoresis in the presence of a nonionic detergent (Triton X-100), a mixture of anonionic and an anionic detergent (Triton X-100 and sodium deoxycholate), and a mixture of a nonionic and a cationic detergent (Triton X-100 and cetyltrimethylammonium bromide). The electrophoretic mobility of the hydrophilic proteins was unaffected in the three detergent mixtures. However, the mobility of the amphiphilic proteins shifted anodally in the Triton X-100-deoxycholate system and cathodally in the Triton X-100-cetyltrimethylammonium bromide system when compared to the mobility in Triton X-100 alone. The detergent-induced shift in mobility provides a simple, rapid, and sensitive method for distinguishing between hydrophilic and amphiphilic proteins.