Ion manipulation and enrichment mass spectrometer for cleavage of disulfide bond via ion/ion reaction.

A novel mass spectrometer with the capability of ion manipulation and enrichment was developed to perform gas-phase ion/ion reactions followed by product ions accumulation. The development of this apparatus opens opportunities for more complex sequences of ion manipulations， thus offers the potential on extensive application involving ion/ion reaction. Here， cleavage of disulfide bond in peptide was demonstrated based upon this ion manipulation and enrichment mass spectrometer. Two typical peptides including S-glutathionylated ARACAKA with an intermolecular disulfide bond， and oxytocin with an intramolecular disulfide bond were chosen as typical samples to demonstrate the ability of the apparatus. After ion/ion reaction between selected peptide cations and periodate ions (IO )， two kinds of product ions (eg， [M + O + H] and [M + H + Na + IO ] ) were enriched with a number of accumulation events. Afterwards， the enriched ions were subjected to activation， and the disulfide bond cleavage was clearly observed from the tandem mass spectra. These results illustrate the potential of this apparatus for ion manipulation performing ion/ion reaction， and low abundance product ion enrichment.