Mass spectrometry for direct determination of proteins in cells: applications in biotechnology and microbiology

A number of different procedures have been developed in recent years that u tilize mass spectrometry for the direct determination of proteins in comple x mixtures of biological origin. Specific examples of these include the use of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS ) or directly combined liquid chromatography-electrospray ionization mass s pectrometry (LC/ESI-MS) for rapid profiling of protein expression in bacter ial and eucaryotic cells and cell-free extracts. Approaches to sample clean up, contaminant removal, and initial separation of analytes on-line for the direct determination of proteins in cells using MALDI- and ESI-MS are disc ussed. Advantages of these techniques over traditional biochemical methods are highlighted, and a critical review of their utility and potential as st andard tools in the biomolecular and microbiological research laboratory is presented.