Two-dimensional electrophoresis for the isolation of integral membrane proteins and mass spectrometric identification.

Acrylamide concentration, urea content, and the trailing ion used for sodium dodecyl sulfate (SDS)-gels modify electrophoretic protein mobilities in a protein-dependent way. Varying these parameters we coupled two SDS-gels to a two-dimensional (2-D) electrophoresis system. Protein spots in 2-D gels are dispersed around a diagonal. Hydrophobic proteins are well separated from water-soluble proteins which is the essential advantage of the novel technique. Mass spectrometric identification of previously unaccessible hydrophobic proteins is now possible.