Top-down protein characterization facilitated by ion/ion reactions on a quadrupole/time of flight platform.
In comparison to bottom-up proteomics approaches, whereby peptides derived from proteolytic digestion are analyzed, top-down approaches, involving direct analysis of intact proteins, provide higher specificity for protein identification and are better-suited for the characterization of sequence variants. However, top-down protein characterization usually requires more sophisticated instrumentation and methodologies to deal with the more complex tandem mass spectra derived from dissociation of high mass multiply charged intact proteins. Gas-phase ion/ion reactions are universally applicable and have proved to be useful in mixture analysis and top-down biomolecule characterization. The coupling of the ion/ion proton transfer reaction in the context of MS/MS has been demonstrated to expand informing power in top-down protein characterization, particularly with platforms that employ electrodynamic ion trap and TOF mass analysis. In addition, probing protein primary structure using ion/ion electron transfer dissociation usually provides extensive structurally informative fragmentation and also allows for the localization of labile PTMs. Here, the performance of the widely used quadrupole/TOF platform, equipped with ion/ion reaction functionality, for top-down protein characterization is summarized, and various methodologies employing ion/ion reactions are reviewed.
Huang
Teng-Yi
TY
Department of Chemistry, Purdue University, West Lafayette, IN 47907-2084, USA.
McLuckey
Scott A
SA
D000595:Amino Acid Sequence; D000818:Animals; D007477:Ions / Q000737:chemistry*; D008969:Molecular Sequence Data; D011506:Proteins / Q000032:analysis*; D040901:Proteomics / Q000295:instrumentation / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000295:instrumentation / Q000379:methods
D007477:Ions; D011506:Proteins