Infrared spectroscopic confirmation of α‐lactone formation in the dissociation of a gaseous amino acid

Wenthold, Paul G.; Koirala, Damodar; Somogyi, Árpád; Poutsma, John C.

doi:10.1002/poc.3606

Cited by 4 publications

(2 citation statements)

References 55 publications

(77 reference statements)

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“…This step at 103 kJ mol –1 was the most energetically demanding of the sequence, but overall the fragmentation pathway was the most energetically favorable of all those computed for the MS 3 ions, in agreement with m/z 121 being the most prominent ion in the MS 3 spectrum (Figure ). The neutral α-lactone has two very different C–O bond lengths, in agreement with computations on other α-lactones. , There is also experimental evidence for the loss of an α-lactone neutral after multiphoton activation …”

Section: Resultssupporting

confidence: 83%

“…30,31 There is also experimental evidence for the loss of an α-lactone neutral after multiphoton activation. 32 Formation of m/z 81, which must be lithiated propanoic acid (Figure 6b), can be envisaged to occur from a variety of the MS 2 ions presented in Figures 3, S4, and S5. A possible pathway is shown in Figure 6b, computations being made from 6P2.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Fragmentation Pathways of Cationized, Saturated, Short-Chain Triacylglycerols: Lithiated and Sodiated Tripropanoyl- and Trihexanoylglycerol

Grossert

Ramaley

2019

J. Am. Soc. Mass Spectrom.

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Many methods, often depending on tandem mass spectrometry, have been developed for analysis of complex mixtures of triacylglycerols (TAGs), especially in clinical diagnostics and food authentication. Understanding the fragmentation mechanisms of cationized TAGs has proved problematic. To obtain a better understanding of viable mechanisms, detailed studies including double- and triple-stage tandem mass spectrometry were made using electrospray ionization on lithiated and sodiated tripropanoyl- and trihexanoylglycerols. Density functional theory computations, including a functional parameterized for van der Waals interactions, were used to correlate computed energies with mass spectra. Losses of both a neutral salt and a neutral acid corresponding to a glycerol side chain were observed as major product ions in MS2 experiments. Signal intensities at low collision energies correlated well with computed energies. However, an important difference between the lithiated and sodiated ions was the appearance of the sodium cation as a major fragmentation product. Computations on the product ions resulting from the loss of a neutral acid indicated multiple structures for the lithiated ions but mainly a single structure for the sodiated ions. The lithiated product ions could be fragmented further (pseudo-MS3) to give additional structural information, whereas the sodiated ions gave only m/z 23. The longer chain TAG, while giving a much less intense mass spectrum than the shorter chain TAG, gave comparable MS2 and MS3 product ion spectra. Taken together, the spectral and computational work described herein offer a new and detailed pathway for collision-induced fragmentation of lithiated and sodiated saturated TAGs.

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Section: Resultssupporting

confidence: 83%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Fragmentation Pathways of Cationized, Saturated, Short-Chain Triacylglycerols: Lithiated and Sodiated Tripropanoyl- and Trihexanoylglycerol

Grossert

Ramaley

2019

J. Am. Soc. Mass Spectrom.

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Infrared Multiphoton Dissociation Spectroscopy with Free‐Electron Lasers: On the Road from Small Molecules to Biomolecules

Jašíková

Roithová

2018

Chemistry A European J

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Infrared multiphoton dissociation (IRMPD) spectroscopy is commonly used to determine the structure of isolated, mass-selected ions in the gas phase. This method has been widely used since it became available at free-electron laser (FEL) user facilities. Thus, in this Minireview, we examine the use of IRMPD/FEL spectroscopy for investigating ions derived from small molecules, metal complexes, organometallic compounds and biorelevant ions. Furthermore, we outline new applications of IRMPD spectroscopy to study biomolecules.

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Participation of C-H Protons in the Dissociation of a Proton Deficient Dipeptide

Koirala

Mistry

Wenthold

2017

J. Am. Soc. Mass Spectrom.

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The dissociation of anionic dipeptides Phe*Gly and GlyPhe*, where Phe* refers to sulfonated phenyl alanine, has been investigated by using ion trap mass spectrometry. The dipeptides undergo collision-induced dissociation (CID) to give the same products, indicating that they rearrange to a common structure before dissociation. The rearrangement does not occur with the dipeptide methyl esters. The structures of the b ions were investigated to determine the effect that having a remote, anionic site has on product formation. Comparison with the CID spectra for authentic structures shows that the b ion obtained from GlyPhe* has predominantly a diketopiperazine structure. The CID spectra for the Phe*Gly b ion and the authentic oxazolone are similar, but differences in intensity suggest a two-component mixture. Isotopic labeling studies are consistent with the formation of two products, with one resulting from loss of a non-mobile proton on the Gly α-carbon. The results are attributed to the formation of an oxazole and oxazolone enol product. Electronic structure calculations predict that the enol structure of the Phe*Gly b ion is lower in energy than the keto version due to intramolecular hydrogen bonding with the sulfonate group. Graphical Abstract ᅟ.

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Infrared spectroscopic confirmation of α‐lactone formation in the dissociation of a gaseous amino acid

Cited by 4 publications

References 55 publications

Fragmentation Pathways of Cationized, Saturated, Short-Chain Triacylglycerols: Lithiated and Sodiated Tripropanoyl- and Trihexanoylglycerol

Fragmentation Pathways of Cationized, Saturated, Short-Chain Triacylglycerols: Lithiated and Sodiated Tripropanoyl- and Trihexanoylglycerol

Infrared Multiphoton Dissociation Spectroscopy with Free‐Electron Lasers: On the Road from Small Molecules to Biomolecules

Participation of C-H Protons in the Dissociation of a Proton Deficient Dipeptide

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