Radical Reactions in the Gas Phase: Recent Development and Application in Biomolecules

Yang Gao,Zhou Peng,Jiexun Bu,Biwei Yang

doi:10.1155/2014/570863

Abstract

This review summarizes recent literature describing the use of gas phase radical reactions for structural characterization of complex biomolecules other than peptides. Specifically, chemical derivatization, in-source chemical reaction, and gas phase ion/ion reactions have been demonstrated as effective ways to generate radical precursor ions that yield structural informative fragments complementary to those from conventional collision-induced dissociation (CID). Radical driven dissociation has been applied to a variety of biomolecules including peptides, nucleic acids, carbohydrates, and phospholipids. The majority of the molecules discussed in this review see limited fragmentation from conventional CID, and the gas phase radical reactions open up completely new dissociation channels for these molecules and therefore yield high fidelity confirmation of the structures of the target molecules. Due to the extensively studied peptide fragmentation, this review focuses only on nonpeptide biomolecules such as nucleic acids, carbohydrates, and phospholipids.

Highlights

The innovation and implementation of novel ion dissociation methods remain the forefront field of mass spectrometry research due to the demand to generate structural informative fragmentation patterns for better identification of a diverse array of molecules
As the size and complexity of the analyte continue to increase, the need for alternatives to collision-induced dissociation (CID) has led to the development of many other dissociation techniques, including electron capture dissociation (ECD) [14], electron transfer dissociation (ETD) [15], ion-ion reactions [16, 17], and photodissociation (PD) [18,19,20]
In order to take advantage of the radical mediated fragmentation without being limited to electron impact ionization (EI), electron transfer reactions have been applied to lipids [59, 60] analogous to the contemporary methods used in the proteomics community

Summary

Introduction

The innovation and implementation of novel ion dissociation methods remain the forefront field of mass spectrometry research due to the demand to generate structural informative fragmentation patterns for better identification of a diverse array of molecules. As the size and complexity of the analyte continue to increase, the need for alternatives to CID has led to the development of many other dissociation techniques, including electron capture dissociation (ECD) [14], electron transfer dissociation (ETD) [15], ion-ion reactions [16, 17], and photodissociation (PD) [18,19,20] Most of these techniques involve the generation of a radical site on the parent ion, and the fragmentation patterns follow an odd electron dissociation mechanism. The radical mediated dissociation technique has been expanded to fields other than peptide and proteins The booming of this technique suggests the wide application of gas phase radical chemistry in biomolecular structural elucidation, including proteins, nucleic acids, glycans, and lipids. Most of the nonconventional ways of generating radical ions in the gas phase discussed in the review require specially modified instrument that is not commercially available, which provides directions for future instrumentation development that can better facilitate the biological researches

Radical Reaction of Nucleic Acids

Radical Reaction of Oligosaccharides

Radical Reaction of Lipids

Conclusion