Electron Transfer Dissociation of Oligonucleotide Cations

Area of Science:

• Mass Spectrometry
• Analytical Chemistry
• Biochemistry

Background:

• Oligonucleotide analysis is crucial for understanding biological processes.
• Electron transfer dissociation (ETD) and collision activated dissociation (CAD) are established mass spectrometry techniques for biomolecule fragmentation.
• Limitations exist in achieving comprehensive sequence information for multi-protonated oligonucleotides using traditional methods.

Purpose of the Study:

• To compare the efficacy of ETD and CAD for fragmenting multi-protonated oligonucleotides and duplexes.
• To investigate the synergistic potential of combining ETD and CAD (ETcaD) for enhanced oligonucleotide sequencing.
• To evaluate the fragmentation patterns and ion abundances generated by ETcaD.

Main Methods:

• Electron transfer dissociation (ETD) was applied to multi-protonated oligonucleotides (6-20mer) and duplexes (12- and 14-mer).
• Collision activated dissociation (CAD) was used as a comparative fragmentation method.
• A sequential approach, termed electron transfer collision activated dissociation (ETcaD), combined ETD followed by CAD on charge-reduced species.

Main Results:

• ETD alone yielded limited backbone cleavage and low-abundance sequence ions, primarily causing charge reduction.
• ETcaD produced rich fragmentation, generating abundant w, a, z, and d ions, while reducing base loss and internal fragments.
• Complete sequencing was achieved for most oligonucleotides studied using ETcaD, with specific backbone cleavages observed in duplexes.

Conclusions:

• ETcaD significantly enhances oligonucleotide sequencing by combining ETD's charge reduction with CAD's extensive fragmentation.
• The ETcaD method provides a powerful tool for comprehensive analysis of oligonucleotide sequences and structures.
• This approach offers improved sequence coverage and reduced artifact ions compared to ETD or CAD alone.