Related Experiment Video
Updated: Jul 24, 2025
11:44
Synthesis and Mass Spectrometry Analysis of Oligo-peptoids
Published on: February 21, 2018
11.0K
Gas Phase Fragmentation Behavior of Proline in Macrocyclic b7 Ions
Cagdas Tasoglu1, Alper Arslanoglu2, Talat Yalcin3
1National Mass Spectrometry Application and Research Center, Integrated Research Centers, Izmir Institute of Technology, Urla-Izmir 35430, Turkey.
Summary
Proline-containing heptapeptides exhibit unique fragmentation, forming macrocyclic structures via head-to-tail cyclization. This unusual behavior under collision-induced dissociation (CID) leads to specific fragmentation pathways involving oxazolone formation.
Area of Science:
- Analytical Chemistry
- Mass Spectrometry
- Proteomics
Background:
- Understanding peptide fragmentation is crucial for protein sequencing and analysis.
- Proline residues significantly influence peptide fragmentation patterns due to their unique cyclic structure.
Purpose of the Study:
- To investigate the detailed fragmentation characteristics of b7 ions from proline-containing heptapeptides.
- To elucidate the unusual fragmentation pathways and structural transformations of these peptides under collision-induced dissociation (CID).
Main Methods:
- Synthesis and analysis of various C-terminally amidated proline-containing heptapeptide model systems.
- Utilized collision-induced dissociation (CID) mass spectrometry to study fragmentation patterns.
- Detailed analysis of b7 ion fragmentation and subsequent product ions.
Main Results:
- Observed that b7 ions undergo head-to-tail cyclization to form macrocyclic structures.
- Fragmentation under CID conditions yields nondirect sequence ions, irrespective of proline position.
- Identified a consistent pathway involving ring opening, N-terminal proline positioning, and oxazolone formation (e.g., PXoxa).
Conclusions:
- Proline-containing heptapeptides display unique and unusual fragmentation behavior.
- Head-to-tail cyclization and subsequent ring opening dictate the fragmentation pathway, leading to specific oxazolone-type ions.
- The findings provide insights into the mass spectrometry-based analysis of peptides containing proline.
Keywords:
ESI MS/MS mass spectrometrymacrocyclizationnondirect sequence ionspeptide fragmentationprolinescrambling of sequenceMore Related Videos
Related Concept Videos
01:20Mass Spectrometry: Molecular Fragmentation Overview
3.3K
The ionization of a molecule into a molecular ion inside the mass spectrometer causes instability in the molecule's structure due to the loss of an electron. This eventually leads to the fragmentation or breaking of some bonds in the molecule. The fragmentation occurs predominantly at specific bonds to yield relatively stable fragments.
One type of fragmentation pattern is the cleavage of a single bond in the molecular ion. The cleavage leads to a radical and a cation. The cleavage can...
One type of fragmentation pattern is the cleavage of a single bond in the molecular ion. The cleavage leads to a radical and a cation. The cleavage can...
3.3K
01:01Mass Spectrometry: Carboxylic Acid, Ester, and Amide Fragmentation
1.4K
The fragmentation patterns observed for compounds such as carboxylic acids, esters, and amides in the mass spectra include ⍺-cleavage and McLafferty rearrangement. Fragmentation by ⍺-cleavage preferentially occurs at the carbon-carbon bond at the ⍺-position next to the carboxylic group to generate a neutral radical and a cation. Long chain compounds with hydrogen at their γ-carbon undergo McLafferty rearrangement to give a radical cation and a neutral alkene.
For example,...
For example,...
1.4K
01:05Mass Spectrometry: Cycloalkane Fragmentation
1.4K
In mass spectrometry, cycloalkanes exhibit distinct fragmentation patterns due to the inherent stability of their molecular ions compared to linear or branched alkanes. The ring structure of cycloalkanes provides additional stability to the molecular ions, often resulting in prominent ion peaks in the mass spectrum.
For example, cyclohexane molecular ions have a mass-to-charge ratio (m/z) of 84, which tends to produce a stronger signal than linear alkanes like hexane. This stability comes from...
For example, cyclohexane molecular ions have a mass-to-charge ratio (m/z) of 84, which tends to produce a stronger signal than linear alkanes like hexane. This stability comes from...
1.4K
00:53Mass Spectrometry: Alkyne Fragmentation
1.5K
The fragmentation of alkynes preferentially occurs at the carbon–carbon bond between the α and β carbon of the alkyne bond to generate a 3-propynyl cation (or propargyl cation). In terminal alkynes, there is the only type of fragmentation that yields the 3-propynyl cation. The unsubstituted 3-propynyl cation exhibits a peak at a mass-to-charge ratio of 39. In internal alkynes, the 3-propynyl cation is substituted. For example, 2-pentyne fragments into methyl-substituted...
1.5K
01:13¹H NMR: Complex Splitting
1.3K
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
1.3K
01:19Mass Spectrometry of Amines
4.3K
In mass spectroscopy, amines undergo fragmentation to give parent ions with odd molecule weights. This observed mass spectrum follows the nitrogen rule: a molecule with an odd number of nitrogen atoms produces a parent ion with an odd molecular weight. The remaining fragments have an even mass.
Amines undergo fragmentation through α cleavage, producing nitrogen-containing cations—iminium ions—and alkyl radicals. Mass spectra of aromatic and cyclic aliphatic amines exhibit...
Amines undergo fragmentation through α cleavage, producing nitrogen-containing cations—iminium ions—and alkyl radicals. Mass spectra of aromatic and cyclic aliphatic amines exhibit...
4.3K