Determination of protein-protein interactions by matrix-assisted laser desorption/ionization mass spectrometry.

A number of different procedures have been developed for use with matrix-assisted laser desorption/ionization mass spectrometry (MALDI/MS) for the analysis of non-covalent protein-protein complexes. These include use of specific matrix and laser combinations, accumulation of "first shot" spectra, modification of pH and solvent conditions during sample preparation and use of cross-linking agents to attach the monomers covalently to each other in the complex. The results have shown the techniques to be effective with some but not all complexes, although cross-linking is the most successful. The physical and chemical nature of the complex is critical and therefore a diversity of approaches is recommended for such studies.