TitleElectron Capture Dissociation of Sodium-Adducted Peptides on a Modified Quadrupole/Time-of-Flight Mass Spectrometer.
Publication TypeJournal Article
Year of Publication2015
AuthorsVoinov VG, Hoffman PD, Bennett SE, Beckman JS, Barofsky DF
JournalJ Am Soc Mass Spectrom
Date Published2015 Dec
KeywordsAmino Acid Sequence, Electrons, Equipment Design, Mass Spectrometry, Models, Molecular, Peptides, Sodium

Electron capture dissociation (ECD), which generally preserves the position of labile post-translational modifications, can be a powerful method for de novo sequencing of proteins and peptides. In this report, ECD product-ion mass spectra of singly and doubly sodiated, nonphosphorylated, and phosphorylated peptides are presented and compared with the ECD mass spectra of their protonated counterparts. ECD of doubly charged, singly sodiated peptides yielded essentially the same sequence information as was produced by the corresponding doubly protonated peptides. The presence of several sodium binding sites on the polypeptide backbone, however, resulted in more complicated spectra. This situation is aggravated by the zwitterionic equilibrium of the free acid peptide precursors. The product-ion spectra of doubly and triply charged peptides possessing two sodium ions were further complicated by the existence of isomers created by the differential distribution of sodium binding sites. Triply charged, phosphorylated precursors containing one sodium, wherein the sodium is attached exclusively to the PO4 group, were found to be as useful for sequence analysis as the fully protonated species. Although sodium adducts are generally minimized during sample preparation, it appears that they can nonetheless provide useful sequence information. Additionally, they enable straightforward identification of a peptide's charge state, even on low-resolution instruments. The experiments were carried out using a radio frequency-free electromagnetostatic cell retrofitted into the collision-induced dissociation (CID) section of a hybrid quadrupole/time-of-flight tandem mass spectrometer. Graphical Abstract ᅟ.

Alternate JournalJ. Am. Soc. Mass Spectrom.
PubMed ID26266643
Grant ListP30 ES000210 / ES / NIEHS NIH HHS / United States
8P41GM103481 / GM / NIGMS NIH HHS / United States
ES000210 / ES / NIEHS NIH HHS / United States
R01RR026275 / RR / NCRR NIH HHS / United States