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Updated: Jul 1, 2025
11:44
Synthesis and Mass Spectrometry Analysis of Oligo-peptoids
Published on: February 21, 2018
10.9K
Mobilize a Proton to Transform the Collision-Induced Dissociation Spectral Pattern of a Cyclic Peptide
Takemichi Nakamura1, Yayoi Hongo1, Ken-Ichi Harada2
1Molecular Structure Characterization Unit, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
Mass Spectrometry (Tokyo, Japan)
|March 4, 2024
Summary
Collision-induced dissociation (CID) of anabaenopeptins revealed distinct fragmentation patterns between anabaenopeptin A and B. The presence of arginine in anabaenopeptin B sequesters protons, hindering cyclic fragmentation, unlike anabaenopeptin A.
Area of Science:
- Analytical Chemistry
- Biochemistry
- Mass Spectrometry
Background:
- Anabaenopeptins are cyclic peptides produced by cyanobacteria.
- Understanding their fragmentation patterns is crucial for structural elucidation and toxin identification.
Purpose of the Study:
- To investigate the collision-induced dissociation (CID) behaviors of anabaenopeptins.
- To elucidate the structural basis for differing fragmentation patterns between anabaenopeptin A and B.
Main Methods:
- Liquid chromatography-tandem mass spectrometry (LC-MS/MS).
- Energy-resolved CID experiments.
- Enzymatic hydrolysis.
Main Results:
- Anabaenopeptin A and B exhibit markedly different CID fragmentation patterns despite similar macrocyclic structures.
- The arginine residue in anabaenopeptin B acts as a protonation site, immobilizing the proton and preventing fragmentation within the cyclic moiety.
- Enzymatic removal of the guanidino group in anabaenopeptin B restored proton mobility and resulted in fragmentation patterns similar to anabaenopeptin A.
Conclusions:
- The exocyclic amino acid residue dictates the protonation site and subsequent fragmentation behavior in anabaenopeptins.
- Proton mobility is key to charge-directed fragmentation in cyclic peptides, consistent with the mobile proton model.
- These findings enhance the structural analysis capabilities for cyanobacterial cyclic peptides using mass spectrometry.
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