Toward Revealing Microcystin Distribution in Mouse Liver Tissue Using MALDI-MS Imaging

Cyanotoxins can be found in water and air during cyanobacterial harmful algal blooms (cHABs) in lakes and rivers. Therefore, it is very important to monitor their potential uptake by animals and humans as well as their health effects and distribution in affected organs. Herein, the distribution of hepatotoxic peptide microcystin-LR (MC-LR) is investigated in liver tissues of mice gavaged with this most common MC congener. Preliminary matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) imaging experiments performed using a non-automated MALDI matrix deposition device and a MALDI-time-of-flight (TOF) mass spectrometer yielded ambiguous results in terms of MC-LR distribution in liver samples obtained from MC-LR-gavaged mice. The tissue preparation for MALDI-MS imaging was improved by using an automated sprayer for matrix deposition, and liver sections were imaged using an Nd:YAG MALDI laser coupled to a 15 Tesla Fourier-transform ion cyclotron resonance (FT-ICR)-mass spectrometer. MALDI-FT-ICR-MS imaging provided unambiguous detection of protonated MC-LR (calculated m/z 995.5560, z = +1) and the sodium adduct of MC-LR (m/z 1017.5380, z = +1) in liver sections from gavaged mice with great mass accuracy and ultra-high mass resolution. Since both covalently bound and free MC-LR can be found in liver of mice exposed to this toxin, the present results indicate that the distribution of free microcystins in tissue sections from affected organs, such as liver, can be monitored with high-resolution MALDI-MS imaging.

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Molecular characterization of petroporphyrins in crude oil by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

Canadian Journal of Chemistry ◽

10.1139/v00-153 ◽

2001 ◽

Vol 79 (5-6) ◽

pp. 546-551 ◽

Cited By ~ 60

Author(s):

Ryan P Rodgers ◽

Christopher L Hendrickson ◽

Mark R Emmett ◽

Alan G Marshall ◽

Mark Greaney ◽

...

Keyword(s):

Mass Spectrometry ◽

Fourier Transform ◽

Crude Oil ◽

Electrospray Ionization ◽

Cyclotron Resonance ◽

Spectrometric Analysis ◽

Ionization Mass ◽

Ion Cyclotron Resonance ◽

Ion Cyclotron ◽

Ft Icr

Petroporphyrin compositional analysis of a heavy crude oil has been realized by isolation and subsequent ESI-FT-ICR mass spectrometric analysis of the porphyrin-containing fractions. Vanadium octaethyl (V=O(II)OEP) and nickel octaethyl (Ni(II)OEP) porphyrin standards were analyzed to determine favorable electrospray ionization conditions and provide insight as to the molecular species present (e.g., adducts, multimers). Standard V=O(II)OEP and Ni(II)OEP solutions revealed the presence of both monomer and dimer species with a greater relative abundance of monomers. In contrast, mass spectral analysis of a porphyrin fraction from Cerro Negro crude oil was dominated by dimeric species. MS3 analysis identified a dioctylphthalate (DOP) contaminant, likely introduced during fractionation of the crude oil. DOP-porphyrin complexes and porphyrin-porphyrin dimers were then identified. Infrared multiphoton dissociation (IRMPD) of dimeric species produced the corresponding monomers with minimal fragmentation. The monomeric petroporphyrins were analyzed to reveal the metal (Ni(II) or V=O(II)), porphyrin type (e.g., etio vs. DPEP), and distribution of alkylation.Key words: petroporphyrin, porphyrin, petroleum, electrospray ionization, mass spectrometry, Fourier transform, ion cyclotron resonance, ICR, FT-ICR, FTMS.

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Laser post-ionisation combined with a high resolving power orbitrap mass spectrometer for enhanced MALDI-MS imaging of lipids

Chemical Communications ◽

10.1039/c7cc02325a ◽

2017 ◽

Vol 53 (53) ◽

pp. 7246-7249 ◽

Cited By ~ 37

Author(s):

S. R. Ellis ◽

J. Soltwisch ◽

M. R. L. Paine ◽

K. Dreisewerd ◽

R. M. A. Heeren

Keyword(s):

Mass Spectrometer ◽

Fold Increase ◽

Maldi Ms ◽

Resolving Power ◽

Coupling Laser ◽

Ms Imaging ◽

Orbitrap Mass Spectrometer

Coupling laser post-ionisation with a high resolving power MALDI Orbitrap mass spectrometer has realised an up to ∼100-fold increase in the sensitivity and enhanced the chemical coverage for MALDI-MS imaging of lipids relative to conventional MALDI.

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Introduction of a 20 kHz Nd:YVO4 laser into a hybrid quadrupole time-of-flight mass spectrometer for MALDI-MS imaging

Analytical and Bioanalytical Chemistry ◽

10.1007/s00216-010-3874-6 ◽

2010 ◽

Vol 397 (8) ◽

pp. 3409-3419 ◽

Cited By ~ 65

Author(s):

Paul J. Trim ◽

Marie-Claude Djidja ◽

Sally J. Atkinson ◽

Keith Oakes ◽

Laura M. Cole ◽

...

Keyword(s):

Mass Spectrometer ◽

Time Of Flight ◽

Maldi Ms ◽

Flight Mass Spectrometer ◽

Ms Imaging

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High-mass MALDI-MS unravels ligand-mediated G protein–coupling selectivity to GPCRs

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2024146118 ◽

2021 ◽

Vol 118 (31) ◽

pp. e2024146118

Author(s):

Na Wu ◽

Agnieszka M. Olechwier ◽

Cyrill Brunner ◽

Patricia C. Edwards ◽

Ching-Ju Tsai ◽

...

Keyword(s):

Complex Formation ◽

G Protein ◽

High Sensitivity ◽

Maldi Ms ◽

High Mass ◽

Ionization Mass ◽

Binding Affinities ◽

C Terminus ◽

Protein Complex Formation ◽

G Protein Coupled

G protein–coupled receptors (GPCRs) are important pharmaceutical targets for the treatment of a broad spectrum of diseases. Although there are structures of GPCRs in their active conformation with bound ligands and G proteins, the detailed molecular interplay between the receptors and their signaling partners remains challenging to decipher. To address this, we developed a high-sensitivity, high-throughput matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) method to interrogate the first stage of signal transduction. GPCR–G protein complex formation is detected as a proxy for the effect of ligands on GPCR conformation and on coupling selectivity. Over 70 ligand–GPCR–partner protein combinations were studied using as little as 1.25 pmol protein per sample. We determined the selectivity profile and binding affinities of three GPCRs (rhodopsin, beta-1 adrenergic receptor [β1AR], and angiotensin II type 1 receptor) to engineered Gα-proteins (mGs, mGo, mGi, and mGq) and nanobody 80 (Nb80). We found that GPCRs in the absence of ligand can bind mGo, and that the role of the G protein C terminus in GPCR recognition is receptor-specific. We exemplified our quantification method using β1AR and demonstrated the allosteric effect of Nb80 binding in assisting displacement of nadolol to isoprenaline. We also quantified complex formation with wild-type heterotrimeric Gαiβγ and β-arrestin-1 and showed that carvedilol induces an increase in coupling of β-arrestin-1 and Gαiβγ to β1AR. A normalization strategy allows us to quantitatively measure the binding affinities of GPCRs to partner proteins. We anticipate that this methodology will find broad use in screening and characterization of GPCR-targeting drugs.

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