Two-dimensional gel electrophoresis/liquid chromatography for the micropreparative isolation of proteins.

Although comprehensive, column-based two-dimensional separation techniques offer enormous resolving power for a complex mixture, they often lack the ability to isolate the separated species for further analysis (e.g., proteins for Edman sequencing). This paper describes a micropreparative two-dimensional separation system for the isolation of proteins from complex mixtures, such as cell lysates. The system is composed of commercially available equipment: continuous-elution tube gel electrophoresis as the first dimension followed by gradient elution, reversed-phase perfusion liquid chromatography as the second dimension with a two-loop sampling valve as the interface between dimensions. The two-dimensional electrophoresis/liquid chromatography system (2D-EP/LC) shows high resolution of proteins since each dimension has orthogonal separation mechanisms (electrophoresis, size/charge; LC, hydrophobicity). Identification of proteins for further analysis is accomplished by superimposing a grid on the computer-generated 3D image.