| 1. |
- Curtis, J M, et al.
(författare)
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Electron ionization-tandem mass spectrometry of glycosphingolipids. I: The identiftcation of compound-specific sequence ions in the collision-induced dissociation spectra of the immonium ions of two isomeric hexaglycosylceramides.
- 1992
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305. ; 3:4, s. 353-9
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Tidskriftsartikel (refereegranskat)abstract
- A permethylated-reduced hexaglycosylceramide in a complex glycolipid mixture isolated from a unique human tissue has been identified by using tandem mass spectrometry (MS/MS). The mass spectrum of this glycolipid mixture, obtained by using in-beam electron ionization, is very complex, and fragment ions derived from the hexaglycosylceramide cannot be distinguished from other ions. Tandem mass spectrometry using a four-sector mass spectrometer gave the mass spectrum of the immonium ion of the permethylated-reduced hexaglycosykeramide (m / z 1645.8), which is characteristic of its structure. Comparison of this MS/MS spectrum with those of two similarly derivatized blood group hexaglycosylceramide isomers permitted identification of the unknown glycolipid structure.
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| 2. |
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| 3. |
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| 4. |
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Nilsson, Carol L, et al.
(författare)
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Characterization of the P13 membrane protein of Borrelia burgdorferi by mass spectrometry.
- 2002
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Ingår i: Journal of the American Society for Mass Spectrometry. - 1044-0305 .- 1879-1123. ; 13:4, s. 295-299
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Tidskriftsartikel (refereegranskat)abstract
- Borrelia burgdorferi sensu lato is a tick-borne pathogen that causes Lyme disease. The characterization of membrane proteins from this and other pathogens may yield a better understanding of the mechanisms of infection and information useful for vaccine design. Characterization of the highly hydrophobic Borrelia outer membrane component P13 from a mutant (OspA- OspB- OspC- and OspD-) strain was undertaken by use of a combination of mass spectrometric methods. In a previous investigation, an electrospray ionization (ESI) mass spectrum of the intact protein provided an average molecular weight that was 20 Da lower than the predicted molecular weight. The mass deviation could be explained by a modification of the N-terminus of the protein such as pyroglutamylation (-17 Da) in combination with the experimental error of measurement, however more information was required. New structural information for this membrane protein was provided by peptide mapping with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) and sequencing with ESI-quadrupole-TOF tandem MS.
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| 9. |
- Palmblad, Magnus, et al.
(författare)
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Automatic Analysis of Hydrogen/Deuterium Exchange Mass Spectra of Peptides and Proteins using Calculations of Isotopic Distributions
- 2001
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Ingår i: Journal of the American Society for Mass Spectrometry. - 1044-0305 .- 1879-1123. ; 12:11, s. 1153-1162
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Tidskriftsartikel (refereegranskat)abstract
- High mass-resolving power has been shown to be useful for studying the conformational dynamics of proteins by hydrogen/deuterium (H/D) exchange. A computer algorithm was developed that automatically identifies peptides and their extent of deuterium incorporation from H/D exchange mass spectra of enzymatic digests or fragment ions produced by collisionally induced dissociation (CID) or electron capture dissociation (ECD). The computer algorithm compares measured and calculated isotopic distributions and uses a fast calculation of isotopic distributions using the fast Fourier transform (FFT). The algorithm facilitates rapid and automated analysis of H/D exchange mass spectra suitable for high-throughput approaches to the study of peptide and protein structures. The algorithm also makes the identification independent on comparisons with undeuterated control samples. The applicability of the algorithm was demonstrated on simulated isotopic distributions as well as on experimental data, such as Fourier transform ion cyclotron resonance (FTICR) mass spectra of myoglobin peptic digests, and CID and ECD spectra of substance P.
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| 10. |
- Sjöberg, Per J. R., et al.
(författare)
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Factors influencing the determination of analyte ion surface partitioning coefficients in electrosprayed droplets
- 2001
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Ingår i: Journal of the American Society for Mass Spectrometry. - 1044-0305. ; 12:9, s. 1002-1010
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Tidskriftsartikel (refereegranskat)abstract
- The observed response in mass spectrometry utilizing electrospray as a sample introduction technique can be affected by a number of factors. In this study a series of two-electrolyte systems was investigated and the mass spectrometric responses were modeled by the use of droplet surface partitioning coefficients and instrumental response factors according to a recently reported method (Sjo¨berg et al., Anal. Chem. 2001, 73, 23–28). The partitioning coefficient and the instrumental response factor were found to be affected by the chosen experimental conditions. Experimental parameters that were investigated include spray position relative to the orifice, spray potential, nebulizer and curtain gas flow rates, ionic strength, and organic content of the sprayed solution. The time history of the generated droplets turned out to be of importance to both the partitioning coefficients and the instrumental response factor. For example, a general increase in the surface partitioning coefficients for the tetrapentylammonium ion was initially observed when the spray was aiming closer to the sampling orifice. Furthermore, it was shown with a small amount of deuterium labeled electrolyte that the total ionic strength and not just the electrolyte concentration influence the instrumental response factor. (J Am Soc Mass Spectrom 2001, 12, 1002–1010)
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| 11. |
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| 12. |
- Zubarev, Roman A., et al.
(författare)
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Isotope depletion of large biomolecules : Implications for molecular mass measurements
- 1998
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Ingår i: Journal of the American Society for Mass Spectrometry. - 1044-0305 .- 1879-1123. ; 9:2, s. 149-156
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Isotope depletion (or enrichment) of large biomolecules is a procedure already used in high resolution Fourier transform ion cyclotron resonance mass spectrometry for improving the reliability and accuracy of biomolecular mass characterization. In this work, effects of isotope depletion on a number of mass spectrometric parameters are systematically studied. Implementation of the isotope depletion techniques in conjunction with lower resolution mass analyzers is discussed as well. We investigate theoretically the position of the centroid of the isotopic mass distributions (centroid mass) and the shift between the monoisotopic and the centroid masses of biopolymers as a function of the isotope abundance (e.g., 12C:13C ratio). The behaviour of other additive mass parameters, like the ratio between the monoisotopic and the first isotopic peak, is also discussed. We address by computer simulations the effects of different instrumental parameters like mass resolution and ion statistics as a function of isotope abundances and from there the achievable mass accuracy for high-mass biopolymers. We assess some of the practical issues of the isotope depletion technique, viz., to what degree and with what accuracy the depletion procedure should be performed for achieving the desired mass accuracy.
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| 13. |
- Abrahamsson, Dimitri, et al.
(författare)
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In Silico Structure Predictions for Non-targeted Analysis : From Physicochemical Properties to Molecular Structures
- 2022
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 33:7, s. 1134-1147
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Tidskriftsartikel (refereegranskat)abstract
- While important advances have been made in high-resolution mass spectrometry (HRMS) and its applications in non-targeted analysis (NTA), the number of identified compounds in biological and environmental samples often does not exceed 5% of the detected chemical features. Our aim was to develop a computational pipeline that leverages data from HRMS but also incorporates physicochemical properties (equilibrium partition ratios between organic solvents and water; Ksolvent–water) and can propose molecular structures for detected chemical features. As these physicochemical properties are often sufficiently different across isomers, when put together, they can form a unique profile for each isomer, which we describe as the “physicochemical fingerprint”. In our study, we used a comprehensive database of compounds that have been previously reported in human blood and collected their Ksolvent–water values for 129 partitioning systems. We used RDKit to calculate the number of RDKit fragments and the number of RDKit bits per molecule. We then developed and trained an artificial neural network, which used as an input the physicochemical fingerprint of a chemical feature and predicted the number and types of RDKit fragments and RDKit bits present in that structure. These were then used to search the database and propose chemical structures. The average success rate of predicting the right chemical structure ranged from 60 to 86% for the training set and from 48 to 81% for the testing set. These observations suggest that physicochemical fingerprints can assist in the identification of compounds with NTA and substantially improve the number of identified compounds.
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| 14. |
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| 15. |
- Alves, G., et al.
(författare)
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Identification of Antibiotic Resistance Proteins via MiCId's Augmented Workflow. A Mass Spectrometry-Based Proteomics Approach
- 2022
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 33:6, s. 917-931
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Tidskriftsartikel (refereegranskat)abstract
- Fast and accurate identifications of pathogenic bacteria along with their associated antibiotic resistance proteins are of paramount importance for patient treatments and public health. To meet this goal from the mass spectrometry aspect, we have augmented the previously published Microorganism Classification and Identification (MiCId) workflow for this capability. To evaluate the performance of this augmented workflow, we have used MS/MS datafiles from samples of 10 antibiotic resistance bacterial strains belonging to three different species: Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The evaluation shows that MiCId's workflow has a sensitivity value around 85% (with a lower bound at about 72%) and a precision greater than 95% in identifying antibiotic resistance proteins. In addition to having high sensitivity and precision, MiCId's workflow is fast and portable, making it a valuable tool for rapid identifications of bacteria as well as detection of their antibiotic resistance proteins. It performs microorganismal identifications, protein identifications, sample biomass estimates, and antibiotic resistance protein identifications in 6-17 min per MS/MS sample using computing resources that are available in most desktop and laptop computers. We have also demonstrated other use of MiCId's workflow. Using MS/MS data sets from samples of two bacterial clonal isolates, one being antibiotic-sensitive while the other being multidrug-resistant, we applied MiCId's workflow to investigate possible mechanisms of antibiotic resistance in these pathogenic bacteria; the results showed that MiCId's conclusions agree with the published study.
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| 16. |
- Amini, Nahid, et al.
(författare)
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SALDI-MS Signal Enhancement Using Oxidized Graphitized Carbon Black Nanoparticles
- 2009
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 20:6, s. 1207-1213
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Tidskriftsartikel (refereegranskat)abstract
- The signal intensity of low-molecular-weight compounds analyzed using surface-assisted laserdesorption/ionization time-of-flight mass spectrometry (SALDI-TOF-MS) was significantlyenhanced when oxidized graphitized carbon black (GCB) particles were used as the desorption/ionization surface. The surface of oxidized GCB contains more carboxylic acid groupsthan non-oxidized GCB. Carboxylic acid groups enhance the efficiency of the ionizationprocess and the desorption of more hydrophobic compounds. A common pharmaceuticalcompound, propranolol, was successfully extracted from Baltic Sea blue mussels and quantifiedusing oxidized GCB as the SALDI surface, whereas deuterated propranolol was used asthe internal standard. The calibration curve showed a wide linear dynamic range of response(0.1–20 g/mL) and good reproducibility (RSD 10%). It was not possible to detectpropranolol in Baltic Sea blue mussels when non-oxidized GCB was used as the SALDI surface.
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| 17. |
- Aminlashgari, Nina, et al.
(författare)
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Surface Assisted Laser Desorption Ionization-Mass Spectrometry (SALDI-MS) for Analysis of Polyester Degradation Products
- 2012
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 23:6, s. 1071-1076
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Tidskriftsartikel (refereegranskat)abstract
- Novel surface assisted laser desorption ionization-mass spectrometry (SALDI-MS) method was developed for rapid analysis of low molecular mass polyesters and their degradation products by laser desorption ionization-mass spectrometry. Three polycaprolactone materials were analyzed by the developed method before and after hydrolytic degradation. The signal-to-noise values obtained by SALDI-MS were 20-100 times higher compared with the ones obtained by using traditional MALDI-MS matrices. A clean background at low mass range and higher resolution was obtained by SALDI-MS. Different nanoparticle, cationizing agent, and solvent combinations were evaluated. Halloysite nanoclay and magnesium hydroxide showed the best potential as SALDI surfaces. The SALDI-MS spectrum of the polyester hydrolysis products was verified by ESI-MS. The developed SALDI-MS method possesses several advantages over existing methods for similar analyses.
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| 18. |
- Anderson, Lissa C., et al.
(författare)
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Intact Protein Analysis at 21 Tesla and X-Ray Crystallography Define Structural Differences in Single Amino Acid Variants of Human Mitochondrial Branched-Chain Amino Acid Aminotransferase 2 (BCAT2)
- 2017
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305. ; 28:9, s. 1796-1804
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Tidskriftsartikel (refereegranskat)abstract
- Structural technologies are an essential component in the design of precision therapeutics. Precision medicine entails the development of therapeutics directed toward a designated target protein, with the goal to deliver the right drug to the right patient at the right time. In the field of oncology, protein structural variants are often associated with oncogenic potential. In a previous proteogenomic screen of patient-derived glioblastoma (GBM) tumor materials, we identified a sequence variant of human mitochondrial branched-chain amino acid aminotransferase 2 as a putative factor of resistance of GBM to standard-of-care-treatments. The enzyme generates glutamate, which is neurotoxic. To elucidate structural coordinates that may confer altered substrate binding or activity of the variant BCAT2 T186R, a ~45 kDa protein, we applied combined ETD and CID top-down mass spectrometry in a LC-FT-ICR MS at 21 T, and X-Ray crystallography in the study of both the variant and non-variant intact proteins. The combined ETD/CID fragmentation pattern allowed for not only extensive sequence coverage but also confident localization of the amino acid variant to its position in the sequence. The crystallographic experiments confirmed the hypothesis generated by in silico structural homology modeling, that the Lys59 side-chain of BCAT2 may repulse the Arg186 in the variant protein (PDB code: 5MPR), leading to destabilization of the protein dimer and altered enzyme kinetics. Taken together, the MS and novel 3D structural data give us reason to further pursue BCAT2 T186R as a precision drug target in GBM. [Figure not available: see fulltext.].
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| 19. |
- Bazoti, Fotini N., et al.
(författare)
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Localization of the noncovalent binding site between amyloid-beta-peptide and oleuropein using electrospray ionization FT-ICR mass spectrometry.
- 2008
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 19:8, s. 1078-1085:19, s. 1078-1085
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Tidskriftsartikel (refereegranskat)abstract
- Abnormal accumulation and aggregation of amyloid-alpha-peptide (AM) eventually lead to the formation and cerebral deposition of amyloid plaques, the major pathological hallmark in Alzheimer's disease (AD). Oleuropein (OE), an Olea europaea L. derived polyphenol, exhibits a broad range of pharmacological properties, such as antioxidant, anti-inflammatory, and antiatherogenic, which could serve as combative mechanisms against several reported pathways involved in the pathophysiology of AD. The reported noncovalent interaction between AM and OE could imply a potential antiamyloidogenic role of the latter on the former via stabilization of its structure and prevention of the adaptation of a toxic beta-sheet conformation. The established P-sheet conformation of the AM hydrophobic carboxy-terminal region and the dependence of its toxicity and aggregational propensity on its secondary structure make the determination of the binding site between AM and OF highly important for assessing the role of the interaction. In this study, two different proteolytic digestion protocols, in conjunction with high-sensitivity electrospray ionization mass spectrometric analysis of the resulting peptide fragments, were used to determine the noncovalent binding site of OE on AM and revealed the critical regions for the interaction.
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| 20. |
- Bazoti, Fotini N., et al.
(författare)
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Noncovalent interaction between amyloid-b-peptide (1-40) and oleuropein studied by electrospray ionization mass spectrometry.
- 2006
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 17:4, s. 568-575
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Tidskriftsartikel (refereegranskat)abstract
- Beta amyloid peptide (A beta) is the major proteinaceous component of senile plaques formed in Alzheimer's disease (AD) brain. The aggregation of A beta is associated with neurodegeneration, loss of cognitive ability, and premature death. It has been suggested that oxidative stress and generation of free radical species have implications in the fibrillation of A beta and its subsequent neurotoxicity. For this reason, it is proposed that antioxidants may offer a protective or therapeutic alternative against amyloidosis. This study is the first report of the formation of the noncovalent complex between A beta or its oxidized form and the natural derived antioxidant oleuropein (OE) by electrospray ionization mass spectrometry (ESI MS). ESI MS allowed the real time monitoring of the complex formation between A beta, OE, and variants thereof. Several experimental conditions, such as elevated orifice potential, low pH values, presence of organic modifier, and ligand concentration were examined, to assess the specificity and the stability of the formed noncovalent complexes.
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| 21. |
- Bieber, Stefan, et al.
(författare)
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Electrospray Ionization Efficiency Predictions and Analytical Standard Free Quantification for SFC/ESI/HRMS
- 2023
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Ingår i: Journal of the American Society for Mass Spectrometry. - 1044-0305 .- 1879-1123. ; 34:7, s. 1511-1518
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Tidskriftsartikel (refereegranskat)abstract
- Supercritical fluid chromatography (SFC) is a promising, sustainable, and complementary alternative to liquid chromatography (LC) and has often been coupled with high resolution mass spectrometry (HRMS) for nontarget screening (NTS). Recent developments in predicting the ionization efficiency for LC/ESI/HRMS have enabled quantification of chemicals detected in NTS even if the analytical standards of the detected and tentatively identified chemicals are unavailable. This poses the question of whether analytical standard free quantification can also be applied in SFC/ES/HRMS. We evaluate both the possibility to transfer an ionization efficiency predictions model, previously trained on LC/ESI/HRMS data, to SFC/ESI/HRMS as well as training a new predictive model on SFC/ESI/HRMS data for 127 chemicals. The response factors of these chemicals ranged over 4 orders of magnitude in spite of a postcolumn makeup flow, expectedly enhancing the ionization of the analytes. The ionization efficiency values were predicted based on a random forest regression model from PaDEL descriptors and predicted values showed statistically significant correlation with the measured response factors (p < 0.05) with Spearman’s rho of 0.584 and 0.669 for SFC and LC data, respectively. Moreover, the most significant descriptors showed similarities independent of the chromatography used for collecting the training data. We also investigated the possibility to quantify the detected chemicals based on predicted ionization efficiency values. The model trained on SFC data showed very high prediction accuracy with median prediction error of 2.20×, while the model pretrained on LC/ESI/HRMS data yielded median prediction error of 5.11×. This is expected, as the training and test data for SFC/ESI/HRMS have been collected on the same instrument with the same chromatography. Still, the correlation observed between response factors measured with SFC/ESI/HRMS and predicted with a model trained on LC data hints that more abundant LC/ESI/HRMS data prove useful in understanding and predicting the ionization behavior in SFC/ESI/HRMS.
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| 22. |
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| 23. |
- Buijs, J, et al.
(författare)
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Inter- and intra-molecular migration of peptide amide hydrogens during electrospray ionization
- 2001
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Ingår i: JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY. - : ELSEVIER SCIENCE INC. - 1044-0305. ; 12:4, s. 410-419
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Tidskriftsartikel (refereegranskat)abstract
- The isotopic exchange of amide hydrogens in proteins in solution strongly depends on the surrounding protein structure, thereby allowing structural studies of proteins by mass spectrometry. However, during electrospray ionization (ESI), gas phase processe
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| 24. |
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| 25. |
- Bökman, C.F., et al.
(författare)
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Relating chromatographic retention and electrophoretic mobility to the ion distribution within electrosprayed droplets
- 2006
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 17:3, s. 318-324
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Tidskriftsartikel (refereegranskat)abstract
- Ions that are observed in a mass spectrum obtained with electrospray mass spectrometry can be assumed to originate preferentially from ions that have a high distribution to the surface of the charged droplets. In this study, a relation between chromatographic retention and electrophoretic mobility to the ion distribution (derived from measured signal intensities in mass spectra and electrospray current) within electrosprayed droplets for a series of tetraalkylammonium ions, ranging from tetramethyl to tetrapentyl, is presented. Chromatographic retention in a reversed-phase system was taken as a measure of the analyte's surface activity, which was found to have a large influence on the ion distribution within electrosprayed droplets. In addition, different transport mechanisms such as electrophoretic migration and diffusion can influence the surface partitioning coefficient. The viscosity of the solvent system is affected by the methanol content and will influence both diffusion and ion mobility. However, as diffusion and ion mobility are proportional to each other, we have, in this study, chosen to focus on the ion mobility parameter. It was found that the influence of ion mobility relative to surface activity on the droplet surface partitioning of analyte ions decreases with increasing methanol content. This effect is most probably coupled to the decrease in droplet size caused by the decreased surface tension at increasing methanol content. The same observation was made upon increasing the ionic strength of the solvent system, which is also known to give rise to a decreased initial droplet size. The observed effect of ionic strength on the droplet surface partitioning of analyte ions could also be explained by the fact that at higher ionic strength, a larger number of ions are initially closer to the droplet surface and, thus, the contribution of ionic transport from the bulk liquid to the liquid/air surface interface (jet and droplet surface), attributable to migration or diffusion will decrease.
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| 26. |
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| 27. |
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| 28. |
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| 29. |
- Egorov, Dmitrii, et al.
(författare)
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Near-Edge Soft X-ray Absorption Mass Spectrometry of Protonated Melittin
- 2018
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305. ; 29:11, s. 2138-2151
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the photoionization and photofragmentation yields of gas-phase multiply protonated melittin cations for photon energies at the K-shell absorption edges of carbon, nitrogen, and oxygen. Two similar experimental approaches were employed. In both experiments, mass selected [melittin+qH]q+ (q=2–4) ions were accumulated in radiofrequency ion traps. The trap content was exposed to intense beams of monochromatic soft X-ray photons from synchrotron beamlines and photoproducts were analyzed by means of time-of-flight mass spectrometry. Mass spectra were recorded for fixed photon energies, and partial ion yield spectra were recorded as a function of photon energy. The combination of mass spectrometry and soft X-ray spectroscopy allows for a direct correlation of protein electronic structure with various photoionization channels. Non-dissociative single and double ionization are used as a reference. The contribution of both channels to various backbone scission channels is quantified and related to activation energies and protonation sites. Soft X-ray absorption mass spectrometry combines fast energy deposition with single and double ionization and could complement established activation techniques. [Figure not available: see fulltext.].
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| 30. |
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| 31. |
- Gatchell, Michael, et al.
(författare)
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Protonated Clusters of Neon and Krypton
- 2019
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 30:12, s. 2632-2636
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Tidskriftsartikel (refereegranskat)abstract
- We present a study of cationic and protonated clusters of neon and krypton. Recent studies using argon have shown that protonated rare gas clusters can have very different magic sizes than pure, cationic clusters. Here, we find that neon behaves similarly to argon, but that the cationic krypton is more similar to its protonated counterparts than the lighter rare gases are, sharing many of the same magic numbers.
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| 32. |
- Goloborodko, AA, et al.
(författare)
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Sequence scrambling in shotgun proteomics is negligible
- 2011
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1879-1123 .- 1044-0305. ; 22:7, s. 1121-1124
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Tidskriftsartikel (refereegranskat)
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| 33. |
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| 34. |
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| 35. |
- Grayson, Scott M., et al.
(författare)
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Advantages of Monodisperse and Chemically Robust "SpheriCal" Polyester Dendrimers as a "Universal" MS Calibrant
- 2014
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 25:3, s. 303-309
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Tidskriftsartikel (refereegranskat)abstract
- The utilization of dendrimer calibrants as an alternative to peptides and proteins for high mass calibration is explored. These synthetic macromolecules exhibited a number of attractive advantages, including exceptional shelf-lives, broad compatibility with a wide range of matrices and solvents, and evenly spaced calibration masses across the mass range examined, 700-30,000 u. The exceptional purity of these dendrimers and the technical simplicity of this calibration platform validate their broad relevance for high molecular weight mass spectrometry.
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| 36. |
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| 37. |
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| 38. |
- Hakansson, K, et al.
(författare)
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Mechanistic studies of multipole storage assisted dissociation
- 2000
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Ingår i: JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY. - : ELSEVIER SCIENCE INC. - 1044-0305. ; 11:3, s. 210-217
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Tidskriftsartikel (refereegranskat)abstract
- The degree and onset of fragmentation in multipole storage assisted dissociation (MSAD) have been investigated as functions of several hexapole parameters. Strict studies of hexapole charge density (number of ions injected) and hexapole storage time were
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| 39. |
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| 40. |
- Jones, Emrys A., et al.
(författare)
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High Speed Data Processing for Imaging MS-Based Molecular Histology Using Graphical Processing Units
- 2012
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 23:4, s. 745-752
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Tidskriftsartikel (refereegranskat)abstract
- Imaging MS enables the distributions of hundreds of biomolecular ions to be determined directly from tissue samples. The application of multivariate methods, to identify pixels possessing correlated MS profiles, is referred to as molecular histology as tissues can be annotated on the basis of the MS profiles. The application of imaging MS-based molecular histology to larger tissue series, for clinical applications, requires significantly increased computational capacity in order to efficiently analyze the very large, highly dimensional datasets. Such datasets are highly suited to processing using graphical processor units, a very cost-effective solution for high speed processing. Here we demonstrate up to 13x speed improvements for imaging MS-based molecular histology using off-the-shelf components, and demonstrate equivalence with CPU based calculations. It is then discussed how imaging MS investigations may be designed to fully exploit the high speed of graphical processor units.
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| 41. |
- Kaldmae, Margit, et al.
(författare)
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Gas-Phase Collisions with Trimethylamine-N-Oxide Enable Activation-Controlled Protein Ion Charge Reduction
- 2019
-
Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 30:8, s. 1385-1388
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Tidskriftsartikel (refereegranskat)abstract
- Modulating protein ion charge is a useful tool for the study of protein folding and interactions by electrospray ionization mass spectrometry. Here, we investigate activation-dependent charge reduction of protein ions with the chemical chaperone trimethylamine-N-oxide (TMAO). Based on experiments carried out on proteins ranging from 4.5 to 35kDa, we find that when combined with collisional activation, TMAO removes approximately 60% of the charges acquired under native conditions. Ion mobility measurements furthermore show that TMAO-mediated charge reduction produces the same end charge state and arrival time distributions for native-like and denatured protein ions. Our results suggest that gas-phase collisions between the protein ions and TMAO result in proton transfer, in line with previous findings for dimethyl- and trimethylamine. By adjusting the energy of the collisions experienced by the ions, it is possible to control the degree of charge reduction, making TMAO a highly dynamic charge reducer that opens new avenues for manipulating protein charge states in ESI-MS and for investigating the relationship between protein charge and conformation.
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| 42. |
- Kaya, Ibrahim, et al.
(författare)
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Multimodal MALDI Imaging Mass Spectrometry Reveals Spatially Correlated Lipid and Protein Changes in Mouse Heart with Acute Myocardial Infarction
- 2020
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 31:10, s. 2133-2142
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Tidskriftsartikel (refereegranskat)abstract
- Acute myocardial infarction (MI) is a cardiovascular disease that remains a major cause of morbidity and mortality worldwide despite advances in its prevention and treatment. During acute myocardial ischemia, the lack of oxygen switches the cell metabolism to anaerobic respiration, with lactate accumulation, ATP depletion, Na+ and Ca2+ overload, and inhibition of myocardial contractile function, which drastically modifies the lipid, protein, and small metabolite profile in the myocardium. Imaging mass spectrometry (IMS) is a powerful technique to comprehensively elucidate the spatial distribution patterns of lipids, peptides, and proteins in biological tissue sections. In this work, we demonstrate an application of multimodal chemical imaging using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), which provided comprehensive molecular information in situ within the same mouse heart tissue sections with myocardial infarction. MALDI-IMS (at 30 mu m per pixel) revealed infarct-associated spatial alterations of several lipid species of sphingolipids, glycerophospholipids, lysophospholipids, and cardiolipins along with the acyl carnitines. Further, we performed multimodal MALDI-IMS (IMS3) where dual polarity lipid imaging was combined with subsequent protein MALDI-IMS analysis (at 30 mu m per pixel) within the same tissue sections, which revealed accumulations of core histone proteins H4, H2A, and H2B along with post-translational modification products, acetylated H4 and H2A, on the borders of the infarcted region. This methodology allowed us to interpret the lipid and protein molecular pathology of the very same infarcted region in a mouse model of myocardial infarction. Therefore, the presented data highlight the potential of multimodal MALDI imaging mass spectrometry of the same tissue sections as a powerful approach for simultaneous investigation of spatial infarct-associated lipid and protein changes of myocardial infarction.
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| 43. |
- Kaya, Ibrahim, et al.
(författare)
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On-Tissue Chemical Derivatization for Comprehensive Mapping of Brain Carboxyl and Aldehyde Metabolites by MALDI-MS Imaging
- 2023
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 34:5, s. 836-846
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Tidskriftsartikel (refereegranskat)abstract
- The visualization of small metabolites by MALDI mass spectrometry imaging in brain tissue sections is challenging due to low detection sensitivity and high background interference. We present an on-tissue chemical derivatization MALDI mass spectrometry imaging approach for the comprehensive mapping of carboxyls and aldehydes in brain tissue sections. In this approach, the AMPP (1-(4-(aminomethyl)phenyl)pyridin-1-ium chloride) derivatization reagent is used for the covalent charge-tagging of molecules containing carboxylic acid (in the presence of peptide coupling reagents) and aldehydes. This includes free fatty acids and the associated metabolites, fatty aldehydes, dipeptides, neurotoxic reactive aldehydes, amino acids, neurotransmitters and associated metabolites, as well as tricarboxylic acid cycle metabolites. We performed sensitive ultrahigh mass resolution MALDI-MS detection and imaging of various carboxyl-and aldehyde containing endogenous metabolites simultaneously in rodent brain tissue sections. We verified the AMPP-derivatized metabolites by tandem MS for structural elucidation. This approach allowed us to image numerous aldehydes and carboxyls, including certain metabolites which had been undetectable in brain tissue sections. We also demonstrated the application of on-tissue derivatization to carboxyls and aldehydes in coronal brain tissue sections of a nonhuman primate Parkinson's disease model. Our methodology provides a powerful tool for the sensitive, simultaneous spatial molecular imaging of numerous aldehydes and carboxylic acids during pathological states, including neurodegeneration, in brain tissue.
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| 44. |
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| 45. |
- Kulyk, Kostiantyn, et al.
(författare)
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Low-Energy Collisions of Protonated Enantiopure Amino Acids with Chiral Target Gases
- 2017
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 28:12, s. 2686-2691
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Tidskriftsartikel (refereegranskat)abstract
- Here we report on the gas-phase interactions between protonated enantiopure amino acids (l- and d-enantiomers of Met, Phe, and Trp) and chiral target gases [(R)- and (S)-2-butanol, and (S)-1-phenylethanol] in 0.1-10.0 eV low-energy collisions. Two major processes are seen to occur over this collision energy regime, collision-induced dissociation and ion-molecule complex formation. Both processes were found to be independent of the stereo-chemical composition of the interacting ions and targets. These data shed light on the currently debated mechanisms of gas-phase chiral selectivity by demonstrating the inapplicability of the three-point model to these interactions, at least under single collision conditions.
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| 46. |
- Kurczy, Michael, 1980, et al.
(författare)
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Nanotome Cluster Bombardment to Recover Spatial Chemistry After Preparation of Biological Samples for SIMS Imaging
- 2010
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 21:5, s. 833-836
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Tidskriftsartikel (refereegranskat)abstract
- A C-60(+) cluster ion projectile is employed for sputter cleaning biological surfaces to reveal spatio-chemical information obscured by contamination overlayers. This protocol is used as a supplemental sample preparation method for time of flight secondary ion mass spectrometry (ToF-SIMS) imaging of frozen and freeze-dried biological materials. Following the removal of nanometers of material from the surface using sputter cleaning, a frozen-patterned cholesterol film and a freeze-dried tissue sample were analyzed using ToF-SIMS imaging. In both experiments, the chemical information was maintained after the sputter dose, due to the minimal chemical damage caused by C-60(+) bombardment. The damage to the surface produced by freeze-drying the tissue sample was found to have a greater effect on the loss of cholesterol signal than the sputter-induced damage. In addition to maintaining the chemical information, sputtering is not found to alter the spatial distribution of molecules on the surface. This approach removes artifacts that might obscure the surface chemistry of the sample and are common to many biological sample preparation schemes for ToF-SIMS imaging.
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| 47. |
- Källsten, Malin, et al.
(författare)
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The potential use of supercharging agents for improved mass spectrometric analysis of monoclonal antibodies and antibody-drug conjugates
- 2022
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Ingår i: joural of the american society for mass spectronomy. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 33:7
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Tidskriftsartikel (refereegranskat)abstract
- The addition of supercharging (SC) reagents in electrospray ionization coupled mass spectrometry (ESI-MS) has demonstrated several advantages for protein analysis such as reduced required mass range of the instrument, narrowed charge-state distribution, increased sensitivity, and adduct suppression. The potential use of SC reagents to improve analyses of larger and complex protein molecules such as monoclonal antibodies and antibody–drug conjugates (ADCs) has not been previously reported. In this study, the effect of seven SC reagents (meta-nitrobenzyl alcohol (m-NBA), dimethyl sulfoxide (DMSO), ortho-nitroanisole (o-NA), propane sultone (PS), ethylene carbonate (EC), propylene carbonate (PC), and sulfolane) on ESI-MS acquired spectra of deglycosylated, intact, and reduced trastuzumab and a vcMMAE–trastuzumab ADC was investigated under denaturing conditions. The addition of any of the SC reagents resulted in a higher average charge state observed for all tested reagents for both trastuzumab and the ADC and a narrower charge-state envelope for o-NA and 1% sulfolane for trastuzumab. However, improved peak shapes or increased sensitivity was observed for several reagents, overall increasing the spectra quality. Finally, it was shown that SC reagents can be safely used for ADC analysis without impacting the obtained drug-to-antibody (DAR) values, as all DAR values were within 0.1 from the control sample.
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| 48. |
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| 49. |
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| 50. |
- Lillja, Johan, et al.
(författare)
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Determination of Monounsaturated Fatty Acid Isomers in Biological Systems by Modeling MS3 Product Ion Patterns
- 2020
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Ingår i: Journal of the American Society for Mass Spectrometry. - WASHINGTON DC USA : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 31:12, s. 2479-2487
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Tidskriftsartikel (refereegranskat)abstract
- Unsaturated free fatty acids are natively present in biological samples as isomers, where double bonds can be situated on different carbons in the acyl chain. While these isomers can have different actions and impacts on biological systems, they are inherently difficult to identify and differentiate by mass spectrometry alone. To address this challenge, several techniques for derivatization of the double bond or metal cationization at the carboxylic group have yielded diagnostic product ions for the respective isomer in tandem mass spectrometry. However, diagnostic product ions do not necessarily reflect quantitative isomeric ratios since fatty acid isomers have different ionization and fragmentation efficiencies. Here, we introduce a simple and rapid approach to predict the quantitative ratio of isomeric monounsaturated fatty acids. Specifically, empirically derived MS3 product ion patterns from fatty acid silver adducts are modeled using a stepwise linear model. This model is then applied to predict the proportion oleic and vaccenic acid in chemically complex samples at individual concentrations between 0.45 and 5.25 mu M, with an average accuracy and precision below 2 and 5 mol %, respectively. We show that by simply including silver ions in the electrospray solvent, isomeric ratios are rapidly predicted in neat standards, rodent plasma, and tissue extract. Furthermore, we use the method to directly map isomeric ratios in tissue sections using nanospray desorption electrospray ionization MS3 imaging without any sample preparation or modification to the instrumental setup. Ultimately, this approach provides a simple and rapid solution to differentiate monounsaturated fatty acids using commonly available commercial mass spectrometers without any instrumental modifications.
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