Benzophenone used as the photochemical reagent for pinpointing C=C locations in unsaturated lipids through shotgun and liquid chromatography-mass spectrometry approaches

Xu, Tengfei; Pi, Zifeng; Song, Fengrui; Liu, Shu; Liu, Zhiqiang

doi:10.1016/j.aca.2018.04.046

Cited by 41 publications

(35 citation statements)

References 31 publications

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“…1f, for analysis of PC 16:0/18:1(9Z) standard, m/z 489 and m/z 578 were diagnostic ions for the C=C location while m/z 396 and m/z 466 could serve as diagnostic ions for C18:1 at sn-2 and C16:0 at sn-2. A systematic screening was performed for a group of carbonyl compounds 52,53 (Supplementary Fig. 7 and Supplementary Table 3) using the nanoESI-MS platform shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Large-scale lipid analysis with C=C location and sn-position isomer resolving power

Cao¹,

Cheng²,

Yang³

et al. 2020

Nat Commun

129

183

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Lipids play a pivotal role in biological processes and lipid analysis by mass spectrometry (MS) has significantly advanced lipidomic studies. While the structure specificity of lipid analysis proves to be critical for studying the biological functions of lipids, current mainstream methods for large-scale lipid analysis can only identify the lipid classes and fatty acyl chains, leaving the C=C location and sn-position unidentified. In this study, combining photochemistry and tandem MS we develop a simple but effective workflow to enable large-scale and near-complete lipid structure characterization with a powerful capability of identifying C=C location(s) and sn-position(s) simultaneously. Quantitation of lipid structure isomers at multiple levels of specificity is achieved and different subtypes of human breast cancer cells are successfully discriminated. Remarkably, human lung cancer tissues can only be distinguished from adjacent normal tissues using quantitative results of both lipid C=C location and sn-position isomers.

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Section: Resultsmentioning

confidence: 99%

Large-scale lipid analysis with C=C location and sn-position isomer resolving power

Cao¹,

Cheng²,

Yang³

et al. 2020

Nat Commun

129

183

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“…Further MS/MS data analysis revealed that photoadducts mask two different photoinduced reactivities of the Bzp towards lipids: C-C bond formation (molecules 2 and 3) and [2+2] cycloaddition leading to oxetane formation (Paternò-Büchi reaction, P-B) on unsaturated OA, LoA (molecule 5 and Figure S13) and oxidised MA. [21][22][23] These two pathways lead to products with the same elemental composition, which makes them undistinguishable at the MS level. MS/MS spectra of the intact photoadducts therefore contain fragment ions originating from both species.…”

Section: Uv-induced Covalent Bond Formation and Rupturementioning

confidence: 99%

“…Bzp is a P-B reagent used for characterisation and quantification of unsaturated lipids in solution or in the gas-phase by MS/MS. 21,24,25 Giving energy to the system results in a retro Paternò-Büchi (retro P-B) reaction leading to ions characteristics of the position of the double bond. 21,26,27 The corresponding  and β ions observed in our study (schemed in Figure 4) are directly observed in MALDI and ESI MS spectra.…”

Section: Uv-induced Covalent Bond Formation and Rupturementioning

confidence: 99%

“…21,24,25 Giving energy to the system results in a retro Paternò-Büchi (retro P-B) reaction leading to ions characteristics of the position of the double bond. 21,26,27 The corresponding  and β ions observed in our study (schemed in Figure 4) are directly observed in MALDI and ESI MS spectra. They are present in MS/MS with very low intensity and with consecutive fragments  and  (Figure 4) in the low m/z region ( Figure 5) proving that both C-C bond and oxetane ring formation coexist.…”

Section: Uv-induced Covalent Bond Formation and Rupturementioning

confidence: 99%

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Benzophenone Photoreactivity in a Lipid Bilayer To Probe Peptide/Membrane Interactions: Simple System, Complex Information

et al. 2019

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Affinity photocrosslinking coupled to mass spectrometry, using benzophenone (Bzp)-functionalized peptides, was used to study the non-covalent interactions of cell-penetrating peptides and lipid membranes. Using biomimetic lipid vesicles composed of saturated and unsaturated negatively charged lipids: DMPG (14:0), DPPG (16:0), DOPG (18:1 cis Δ 9), 18:1 (trans Δ 9) PG and DLoPG (18:2 cis Δ 9, 12), allowed to observe all the classical and less common reactivities of Bzp described in the literature by direct MS analysis: C=C double bond formation on saturated fatty acids, covalent adducts formation via classical CC bond and Paternò-Büchi oxetane formation followed or not by fragmentation (retro-Paternò-Büchi) as well as photosensitisation of unsaturated lipids leading to lipid dimers. All these reactions can occur concomitantly in a single complex biological system: a membrane-active peptide inserted within a phospholipid bilayer. We also detect oxidation species due to the presence of radical oxygen species. This work represents a noteworthy improvement for the characterisation of interacting partners using Bzp photocrosslinking, and shows how to exploit in an original way the different reactivities of Bzp in the context of a lipid membrane. We propose an analytical workflow for the interpretation of MS spectra, giving access to information on the CPP/lipid interaction at a molecular level such as depth of insertion or membrane fluidity in the CPP vicinity. An application of this workflow illustrates the role of cholesterol in the CPP/lipids interaction. Supporting information Available Detailed experimental procedures and (R/W)9 results are given in the Supporting Information.

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“…Thus, a micro‐flow reactor based on a microchip is a promising future setup for further reduction of reaction times. An additional point of interest is the realization of the LC/PB‐MS method with other carbonyl compounds, e.g., benzophenone, aiming at higher quantum yields . However, direct hyphenation of the online reaction with HPLC showed encouraging results for future analysis of further complex mixtures and lipid structures of various origin.…”

Section: Discussionmentioning

confidence: 99%

Localization of double‐bond positions in lipids by tandem mass spectrometry succeeding high‐performance liquid chromatography with post‐column derivatization

Jeck

Korf

Vosse

et al. 2018

Rapid Comm Mass Spectrometry

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Rationale: Lipids are a group of biomolecules known for their importance in a broad variety of biological tasks, which is attributed to the diversity of their molecular structures.The exact position of the double bond in a lipid affects its biological properties. Therefore, the determination of its position is highly important. Nevertheless, the unambiguous assignment is still a challenging task and requires the development of new approaches. Methods: A novel method for pinpointing double-bond positions in lipids is presented based on the photochemical Paternὸ-Büchi reaction. Therefore, the reaction was performed using a post-column derivatization by ultraviolet (UV) light irradiation (254 nm) and an additional constant flow of acetone. The acetone adduct was formed due to the reaction of acetone with the double bond resulting in an oxetane. Subsequent fragmentation experiments generated diagnostic fragments allowing the localization of double-bond positions. Results: Intending online hyphenation with high-performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS), the reaction was optimized regarding parameters such as reaction time and the influence of trace oxygen as well as solvents. An additional separation of the reaction products by means of HPLC enabled further characterization of the chemical structures formed by UV irradiation. To demonstrate the applicability of the developed method, a mixture of the constitutional phospholipid isomers bis(monooleoylglycero) phosphate and dioleoyl-phosphatidylglycerol was analyzed regarding their double-bond positions, and lipids from an extract of the green alga Chlamydomonas reinhardtii were investigated. Conclusions: The successful hyphenation of HPLC/MS/MS with the online reaction was demonstrated for localization of double bonds in single lipids, lipid mixtures, and complex biological samples. Matrix effects can be reduced and further structural information, for example in case of constitutional isomers, can be obtained. This opens up new avenues for pinpointing lipid double-bond positions even in complex samples.

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Benzophenone used as the photochemical reagent for pinpointing C=C locations in unsaturated lipids through shotgun and liquid chromatography-mass spectrometry approaches

Cited by 41 publications

References 31 publications

Large-scale lipid analysis with C=C location and sn-position isomer resolving power

Large-scale lipid analysis with C=C location and sn-position isomer resolving power

Benzophenone Photoreactivity in a Lipid Bilayer To Probe Peptide/Membrane Interactions: Simple System, Complex Information

Localization of double‐bond positions in lipids by tandem mass spectrometry succeeding high‐performance liquid chromatography with post‐column derivatization

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