Tandem Mass Spectrometry for Peptide and Protein Sequence Analysis

Proteins are involved in nearly every aspect of cellular function. In fact, the characterization of proteins has become such a significant part of modern biology, it has inspired a new discipline: proteomics—the classification of the protein complement expressed by the genome of an organism. Technology development has driven, and continues to drive, rapid evolution in this field. Seventeen years ago innovations in biomolecule ionization [electrospray (1) and matrix-assisted laser desorption/ionization (2), ESI and MALDI, respectively] placed mass spectrometry (MS) at the forefront of this emerging discipline. Although biological MS was pursued prior to this work, these techniques are generally credited for expanding the field substantially. With these tools, mass spectrometrists could for the first time, easily and robustly, convert condensed phase peptides or even whole proteins to intact gas phase ions.