Dissociation of Even‐Electron Ions

Afonso, Carlos; Cole, Richard B.; Tabet, Jean‐Claude

doi:10.1002/9780470588901.ch17

Cited by 8 publications

(13 citation statements)

References 191 publications

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“…These tautomers provide the critical link between the complex dissociation pathways observed for uracil and a simple theory that can describe dissociation via chargedirected mechanisms [24] to form products with a stabilized charge [25]. By taking tautomerization into account, we can now explain all observed experimental data from an extensive isotopic labeling study, accurate mass measurements, and sequential tandem MS.…”

Section: Ionization Tautomerization and Collisional Activation Of Umentioning

confidence: 88%

“…For small, highly conjugated ions such as uracil, the charge site mediates all reaction steps, including proton transfer, charge redistribution, tautomerization, and ultimately dissociation [24]. Charge-directed dissociations proceed through favorable (stabilized) transition states to produce stable neutral molecules and product-ions.…”

Section: Ionization Tautomerization and Collisional Activation Of Umentioning

confidence: 99%

“…Based on the hundreds of reaction mechanisms we have examined in our previously published [1,[4][5][6][7]18] and unpublished studies and the fundamental basics of ion dissociation [24,25], we have developed a unique approach for describing MS/MS reactions of small conjugate ions during CID. In general: (1) Reaction steps can be described as charge-directed processes [24].…”

Section: Introductionmentioning

confidence: 99%

“…Ions with a fixed charge site or little conjugation can undergo charge-remote dissociation that is similar in mechanism to thermal degradation of neutral molecules [23,24]. In contrast, the small, highly conjugated ions of NA bases typically react through charge-mediated processes [1,4,6,7,18,24]. Intramolecular chemical reactions of precursor ions are initiated by a charge site, and the stability of specific conformations of precursor ions and product-ions are determined by inductive effects, steric effects, and resonance in the conjugated system of double bonds.…”

Section: Introductionmentioning

confidence: 99%

“…In general: (1) Reaction steps can be described as charge-directed processes [24]. (2) Collisionally excited ions can adopt higher energy conformations that are the precursors to dissociation [18,24,26].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Revisiting the Reactivity of Uracil During Collision Induced Dissociation: Tautomerism and Charge-Directed Processes

Beach

Gabryelski

2012

J. Am. Soc. Mass Spectrom.

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In our recent work towards the nontarget identification of products of nucleic acid (NA) damage in urine, we have found previous work describing the dissociation of NA bases not adequate to fully explain their observed reactivity. Here we revisit the gas-phase chemistry of protonated uracil (U) during collision induced dissociation (CID) using two modern tandem mass spectrometry techniques; quadrupole ion trap (QIT) and quadrupole time of flight (Q-TOF). We present detailed mechanistic proposals that account for all observed products of our experiments and from previous isotope labeling data, and that are supported by previous ion spectroscopy results and theoretical work. The diverse product-ions of U cannot be explained adequately by only considering the lowest energy form of protonated U as a precursor. The tautomers adopted by U during collisional excitation make it possible to relate the complex reactivity observed to reasonable mechanistic proposals and feasible product-ion structures for this small highly conjugated heterocycle. These reactions proceed from four different stable tautomers, which are excited to a specific activated precursor from which dissociation can occur via a charge-directed process through a favorable transition state to give a stabilized product. Understanding the chemistry of uracil at this level will facilitate the identification of new modified uracil derivatives in biological samples based solely on their reactivity during CID. Our integrated approach to describing ion dissociation is widely applicable to other NA bases and similar classes of biomolecules.

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Section: Ionization Tautomerization and Collisional Activation Of Umentioning

confidence: 88%

Section: Ionization Tautomerization and Collisional Activation Of Umentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Revisiting the Reactivity of Uracil During Collision Induced Dissociation: Tautomerism and Charge-Directed Processes

Beach

Gabryelski

2012

J. Am. Soc. Mass Spectrom.

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Origin and characterization of cyclodepsipeptides: Comprehensive structural approaches with focus on mass spectrometry analysis of alkali‐cationized molecular species

Liuu,

Damont,

Perret

et al. 2024

Mass Spectrometry Reviews

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Cyclodepsipeptides (CDPs) represent a huge family of chemically and structurally diverse molecules with a wide ability for molecular interactions. CDPs are cyclic peptide‐related natural products made up of both proteinogenic and nonproteinogenic amino acids linked by amide and ester bonds. The combined use of different analytical methods is required to accurately determine their integral structures including stereochemistry, thus allowing deeper insights into their often‐intriguing bioactivities and their possible usefulness. Our goal is to present the various methods developed to accurately characterize CDPs. Presently, Marfey's method and NMR (nuclear magnetic resonance) are still considered the best for characterizing CDP configuration. Nevertheless, electrospray‐high resolution tandem mass spectrometry (ESI‐HRMS/MS) is of great value for efficiently resolving CDP's composition and sequences. For instance, recent data shows that the fragmentation of cationized CDPs (e.g., [M + Li]+ and [M + Na]+) leads to selective cleavage of ester bonds and specific cationized product ions (b series) useful to get unprecedented sequence information. Thus, after a brief presentation of their structure, biological functions, and biosynthesis, we also provide a historic overview of these various analytical approaches as well as their advantages and limitations with a special emphasis on the emergence of methods based on HRMS/MS through recent fundamental works and applications.

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Atypical cleavage of protonated N-fatty acyl amino acids derived from aspartic acid evidenced by sequential MS3 experiments

Boukerche¹,

Alvès²,

Faouder³

et al. 2016

Amino Acids

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Lipidomics calls for information on detected lipids and conjugates whose structural elucidation by mass spectrometry requires to rationalization of their gas phase dissociations toward collision-induced dissociation (CID) processes. This study focused on activated dissociations of two lipoamino acid (LAA) systems composed of N-palmitoyl acyl coupled with aspartic and glutamic acid mono ethyl esters (as LAA and LAA). Although in MS/MS, their CID spectra show similar trends, e.g., release of water and ethanol, the [(LAA+H)-CHOH] product ions dissociate via distinct pathways in sequential MS experiments. The formation of all the product ions is rationalized by charge-promoted cleavages often involving stepwise processes with ion isomerization into ion-dipole prior to dissociation. The latter explains the maleic anhydride or ketene neutral losses from N-palmitoyl acyl aspartate and glutamate anhydride fragment ions, respectively. Consequently, protonated palmitoyl acid amide is generated from LAA whereas LAA leads to the [*E+H-HO] anhydride. The former releases ammonia to provide acylium, which gives the C H and C H carbenium series. This should offer structural information, e.g., to locate either unsaturation(s) or alkyl group branching present on the various fatty acyl moieties of lipo-aspartic acid in further studies based on MS experiments.

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Dissociation of Even‐Electron Ions

Cited by 8 publications

References 191 publications

Revisiting the Reactivity of Uracil During Collision Induced Dissociation: Tautomerism and Charge-Directed Processes

Revisiting the Reactivity of Uracil During Collision Induced Dissociation: Tautomerism and Charge-Directed Processes

Origin and characterization of cyclodepsipeptides: Comprehensive structural approaches with focus on mass spectrometry analysis of alkali‐cationized molecular species

Atypical cleavage of protonated N-fatty acyl amino acids derived from aspartic acid evidenced by sequential MS3 experiments

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