Two-dimensional analysis of recombinant E. coli proteins using capillary isoelectric focusing electrospray ionization mass spectrometry.

On-line combination of capillary isoelectric focusing with electrospray ionization mass spectrometry is applied for a two-dimensional analysis of Escherichia coli proteins. The proteins are focused and cathodically mobilized in a polyacrylamide coated capillary. At the end of the capillary, various protein zones are analyzed by mass spectrometry coupled through an electrospray interface. Comparisons with silver-stained two-dimensional gel electrophoresis are made with regard to mass determination, resolution, speed, and sensitivity. Direct identification of a recombinant fusion protein of glutathione S-transferase and striped bass growth hormone is achieved without any prior protein isolation procedures.