Preferential Fragmentation of Protonated Gas-Phase Peptide Ions Adjacent to Acidic Amino Acid Residues

摘要

Matrix-assisted laser desorption/ionization (MALDI) is an effective method for producing protonated peptide and protein ions in the gas phase. Together with electrospray ionization, MALDI has become an ionization method of choice for analyzing peptides and proteins by mass spectrometry (MS). The analyses are usually carried out by measuring the molecular masses of the intact polypeptides or peptide fragments produced by proteolysis or chemical degradation of proteins in solution. An alternative method for obtaining detailed primary structural information uses fragmentation of the protonated peptides in the gas phase followed by MS analysis of the fragment ions. A powerful variation of this approach, called tandem MS, employs mass spectrometric selection of the peptide ion of interest prior to fragmentation, followed by analysis of the fragment ions.