Gas-Phase Oxidation via Ion/Ion Reactions: Pathways and Applications

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Biochemistry

Background:

• Gas-phase ion/ion reactions offer unique pathways for chemical modification of biomolecules.
• Selective oxidation of specific residues and bonds in peptides and DNA is crucial for structural analysis.
• Understanding oxidation mechanisms is key to developing novel analytical tools.

Purpose of the Study:

• To provide an overview of gas-phase oxidation pathways for peptides and DNA via ion/ion reactions.
• To explore potential applications of these oxidation chemistries in biomolecular analysis.
• To compare the efficacy of different oxidizing reagents, namely periodate and persulfate anions.

Main Methods:

• Utilized ion/ion reactions with periodate and peroxymonosulfate anions for oxidation of thioethers, disulfide bonds, and S-nitrosylated cysteine residues.
• Investigated oxidation of neutral basic sites on peptides, generating various oxidized species.
• Employed sulfate radical anion for efficient generation of molecular radical cations from peptides.

Main Results:

• Demonstrated oxidation of thioethers, disulfide bonds, and S-nitrosylated cysteine residues to [M+H+O]+ derivatives.
• Showcased oxidation of neutral basic sites yielding [M+H+O]+, [M-H]+, and [M-H-NH3]+ species.
• Successfully generated molecular radical cations from peptides, enabling side-chain fragmentation and dehydroalanine formation for residue localization.

Conclusions:

• Gas-phase ion/ion oxidation reactions provide versatile pathways for generating diverse oxidized structures from peptides and DNA.
• These chemistries are applicable for identifying and localizing S-alkyl cysteine residues, cleaving disulfide bonds, and generating radical cations.
• The presented methods offer powerful tools for advanced structural characterization of peptides and DNA.