Analysis of protein sequences and protein complexes by matrix-assisted laser desorption/ionization mass spectrometry

In the context of proteome analysis, matrix-assisted laser desorption/ioniz ation mass spectrometry (MALDI-MS) can fulfil the two tasks of primary stru cture verification and protein identification. As an illustration of the fi rst of these tasks, the sequence of Eschericha colt isoleucyl-tRNA syntheta se, a protein with 15 reported sequence conflicts, has been established by means of MALDI mass mapping. The identification of mitochondrial proteins p articipating in a yeast supramolecular complex exhibiting NADH dehydrogenas e activity highlights the performances of MALDI-MS for the second task. The spectral suppression phenomenon occurring for complex peptide mixtures ana lysed by MALDI is discussed, as well as the role of post-source decay analy sis for confident protein identification.