Beam‐type collisional activation of polypeptide cations that survive ion/ion electron transfer

Abstract

Doubly protonated peptides that undergo an electron transfer reaction without dissociation in a linear ion trap can be subjected to beam-type collisional activation upon transfer from the linear ion trap into an adjacent mass analyzer, as demonstrated here with a hybrid triple quadrupole/linear ion trap system. The activation can be promoted by use of a DC offset difference between the ion trap used for reaction and the ion trap into which the products are injected of 12-16 V, which gives rise to energetic collisions between the transferred ions and the collision/bath gas employed in the linear ion trap used for ion/ion reactions. Such a process can be executed routinely on hybrid linear ion trap/triple quadrupole tandem mass spectrometers and is demonstrated here with several model peptides as well as a few dozen tryptic peptides. Collisional activation of the peptide precursor ions that survive electron transfer frequently provides structural information that is absent from the precursor ions that fragment spontaneously upon electron transfer. The degree to which additional structural information is obtained by collisional activation of the surviving singly charged peptide ions depends upon peptide size. Little or no additional structural information is obtained from small peptides (<8 residues) due to the high electron transfer dissociation (ETD) efficiencies noted for these peptides as well as the extensive sequence information that tends to be forthcoming from ETD of such species. Collisional activation of the surviving electron transfer products provided greatest benefit for peptides of 8-15 residues.

Charge state dependent fragmentation of gaseous α-synuclein cations via ion trap and beam-type collisional activation

“…Beam-type CID experiments were performed using the same instrument. The experimental procedures for ion parking and beam-type CID used here have been reported in detail elsewhere [50,51]. In brief, the following experimental sequence was used: 1) cation accumulation (200–250 ms) in Q0; 2) ion parking in Q0 (to obtain low charge state species); 3) precursor ion isolation via Q1; 4) beam-type CID in Q2 with the injection energy determined by the DC rod offset difference between Q0 and Q2; 5) mutual storage mode ion-ion reactions in Q2; and 6) mass analysis of ions using a reflectron time-of-flight mass analyzer.…”

Coupling Capillary Zone Electrophoresis with Electron Transfer Dissociation and Activated Ion Electron Transfer Dissociation for Top-Down Proteomics

“…, higher m/z values). 37–39 As precursor m/z values increase, so increases the likelihood of non-dissociative electron transfer (ETnoD), 40 a process in which backbone bond cleavage occurs but the fragment ions remain bound together by non-covalent interactions. ETnoD reduces precursor-to-product ion conversion, limiting the sequence information gleaned from an ETD MS/MS event.…”

Enhanced Electron Transfer Dissociation of Peptides Modified at C-terminus with Fixed Charges

“…For example, McLafferty et al developed activated ion ECD, a method combining electron capture and collisional activation, to increase sequence coverage for top-down proteomics applications [30]. Both the Coon [27] and McLuckey groups [31,32] have developed methods that combine electron activation with subsequent collisional activation of the charge-reduced ions (in a tandem process sometimes abbreviated as ETcaD), resulting in improved sequence coverage for peptides in low charge states. Our group also reported that ETcaD of N-terminal derivatized peptides afforded simplified MS/MS spectra containing predominantly C-terminal z-type ions, leading to successful de novo sequencing of peptides [33].…”