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In light of recent conflicting reports regarding the hydroformylation catalytic activity derived from cationic Co(II) precatalysts of the form [Co(acac)(bis(phosphine))]BF4, the synthetic procedures and characterization of [Co(acac)(dppBz)]BF4, 1, are evaluated. Leveraging calibrated ESI-TOF MS methodologies, substantial quantities of Co(acac)2(dppBz), 2, were observed within samples of 1. The source of the impurity, 2, is determined to derive from incomplete protonolysis of the Co(acac)2 precursor and ligand scrambling occurring during the synthesis of 1. Revised synthetic procedures using lower temperature conditions and longer reaction times afford analytically pure samples of 1 based on ESI-TOF MS and NMR spectroscopic analysis. Complex 1 is demonstrated to act as a hydroformylation precatalyst for the conversion of 1-hexene to 1-heptanal under relatively mild conditions at 51.7 bar and 140 °C. The presence of impurity 2 is shown to dramatically decrease the catalytic performance derived from 1.
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We report the structural, biochemical, and functional characterization of the product of gene PA0962 from Pseudomonas aeruginosa PAO1. The protein, termed Pa Dps, adopts the Dps subunit fold and oligomerizes into a nearly spherical 12-mer quaternary structure at pH 6.0 or in the presence of divalent cations at neutral pH and above. The 12-Mer Pa Dps contains two di-iron centers at the interface of each subunit dimer, coordinated by conserved His, Glu, and Asp residues. In vitro, the di-iron centers catalyze the oxidation of Fe2+ utilizing H2O2 (not O2) as an oxidant, suggesting Pa Dps functions to aid P. aeruginosa to survive H2O2-mediated oxidative stress. In agreement, a P. aeruginosa Δdps mutant is significantly more susceptible to H2O2 than the parent strain. The Pa Dps structure harbors a novel network of Tyr residues at the interface of each subunit dimer between the two di-iron centers, which captures radicals generated during Fe2+ oxidation at the ferroxidase centers and forms di-tyrosine linkages, thus effectively trapping the radicals within the Dps shell. Surprisingly, incubating Pa Dps and DNA revealed unprecedented DNA cleaving activity that is independent of H2O2 or O2 but requires divalent cations and 12-mer Pa Dps.
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Proteínas Bacterianas , División del ADN , Proteínas de Unión al ADN , Peróxido de Hidrógeno , Estrés Oxidativo , Pseudomonas aeruginosa , Proteínas Bacterianas/metabolismo , Cationes Bivalentes , ADN/metabolismo , Peróxido de Hidrógeno/metabolismo , Hierro/metabolismo , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/metabolismo , Proteínas de Unión al ADN/metabolismoRESUMEN
Stem cell-based therapies carry significant promise for treating human diseases. However, clinical translation of stem cell transplants for effective treatment requires precise non-destructive evaluation of the purity of stem cells with high sensitivity (<0.001% of the number of cells). Here, a novel methodology using hyperspectral imaging (HSI) combined with spectral angle mapping-based machine learning analysis is reported to distinguish differentiating human adipose-derived stem cells (hASCs) from control stem cells. The spectral signature of adipogenesis generated by the HSI method enables identifying differentiated cells at single-cell resolution. The label-free HSI method is compared with the standard techniques such as Oil Red O staining, fluorescence microscopy, and qPCR that are routinely used to evaluate adipogenic differentiation of hASCs. HSI is successfully used to assess the abundance of adipocytes derived from transplanted cells in a transgenic mice model. Further, Raman microscopy and multiphoton-based metabolic imaging is performed to provide complementary information for the functional imaging of the hASCs. Finally, the HSI method is validated using matrix-assisted laser desorption/ionization-mass spectrometry imaging of the stem cells. The study presented here demonstrates that multimodal imaging methods enable label-free identification of stem cell differentiation with high spatial and chemical resolution.
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Post-traumatic stress disorder (PTSD) is a widespread psychiatric injury that develops serious life-threatening symptoms like substance abuse, severe depression, cognitive impairments, and persistent anxiety. However, the mechanisms of post-traumatic stress injury in brain are poorly understood due to the lack of practical methods to reveal biochemical alterations in various brain regions affected by this type of injury. Here, we introduce a novel method that provides quantitative results from Raman maps in the paraventricular nucleus of the thalamus (PVT) region. By means of this approach, we have shown a lipidome comparison in PVT regions of control and PTSD rat brains. Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry was also employed for validation of the Raman results. Lipid alterations can reveal invaluable information regarding the PTSD mechanisms in affected regions of brain. We have showed that the concentration of cholesterol, cholesteryl palmitate, phosphatidylinositol, phosphatidylserine, phosphatidylethanolamine, sphingomyelin, ganglioside, glyceryl tripalmitate and sulfatide changes in the PVT region of PTSD compared to control rats. A higher concentration of cholesterol suggests a higher level of corticosterone in the brain. Moreover, concentration changes of phospholipids and sphingolipids suggest the alteration of phospholipase A2 (PLA2) which is associated with inflammatory processes in the brain. Our results have broadened the understanding of biomolecular mechanisms for PTSD in the PVT region of the brain. This is the first report regarding the application of Raman spectroscopy for PTSD studies. This method has a wide spectrum of applications and can be applied to various other brain related disorders or other regions of the brain.
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Núcleos Talámicos de la Línea Media , Trastornos por Estrés Postraumático , Animales , Encéfalo , Lipidómica , Fosfolípidos , RatasRESUMEN
A combination of matrix-assisted laser desorption ionization (MALDI) imaging and infrared (IR) laser ablation sampling with offline electrospray ionization mass spectrometry (ESI-MS) was used to determine the distribution of the fungicide imazalil in apples. MALDI images were used to determine the penetration depth of imazalil up to 7 days after its application. IR laser ablation sampling and ESI-MS were used to quantify the rate of penetration of the fungicide, which was determined to be approximately 1 mm per day. Imazalil concentration decreased in the apple skin over the course of the experiment, and after 7 days the fungicide was detected at 0.015 ppm 6 mm inside the apple. Approximately 60% of the pesticide remained in the skin after 7 days. This work demonstrates the utility of MALDI imaging for spatial localization of fungicide in fruit in combination with IR laser ablation and ESI-MS for quantitative analysis.
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Fungicidas Industriales/análisis , Rayos Láser , Malus/química , Espectrometría de Masa por Láser de Matriz Asistida de Ionización DesorciónRESUMEN
High resolving power ion mobility (IM) allows for accurate characterization of complex mixtures in high-throughput IM mass spectrometry (IM-MS) experiments. We previously demonstrated that pure component IM-MS data can be extracted from IM unresolved post-IM/collision-induced dissociation (CID) MS data using automated ion mobility deconvolution (AIMD) software [Matthew Brantley, Behrooz Zekavat, Brett Harper, Rachel Mason, and Touradj Solouki, J. Am. Soc. Mass Spectrom., 2014, 25, 1810-1819]. In our previous reports, we utilized a quadrupole ion filter for m/z-isolation of IM unresolved monoisotopic species prior to post-IM/CID MS. Here, we utilize a broadband IM-MS deconvolution strategy to remove the m/z-isolation requirement for successful deconvolution of IM unresolved peaks. Broadband data collection has throughput and multiplexing advantages; hence, elimination of the ion isolation step reduces experimental run times and thus expands the applicability of AIMD to high-throughput bottom-up proteomics. We demonstrate broadband IM-MS deconvolution of two separate and unrelated pairs of IM unresolved isomers (viz., a pair of isomeric hexapeptides and a pair of isomeric trisaccharides) in a simulated complex mixture. Moreover, we show that broadband IM-MS deconvolution improves high-throughput bottom-up characterization of a proteolytic digest of rat brain tissue. To our knowledge, this manuscript is the first to report successful deconvolution of pure component IM and MS data from an IM-assisted data-independent analysis (DIA) or HDMSE dataset.
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Infrared (IR) laser ablation was used to remove material from tissue sections mounted on microscope slides, with subsequent capture in a solvent-containing microcentrifuge tube. Experiments conducted with a 3200-bp double-stranded plasmid DNA template demonstrated IR-laser ablation transfer of intact DNA. The transfer efficiency and the molecular integrity of the captured DNA were evaluated using Sanger sequencing, gel electrophoresis, and fluorimetric analysis. The plasmid DNA was reproducibly transferred with an efficiency of 59 ± 3% at laser fluences of between 10 and 20 kJ/m2 at a wavelength of 3 µm. IR laser ablation sample transfer was then used to ablate and capture DNA from 50-µm-thick rat brain and kidney tissue sections. DNA was extracted from the captured material using five commercial DNA extraction kits that employed significantly divergent methodologies, with all kits recovering sufficient DNA for successful amplification by polymerase chain reaction (PCR). Four sets of primers were employed, targeting one region of the CYP 11b2 gene (376 bp) and three different regions of the Snn1g gene (298, 168, and 281 bp). The PCR results were not consistently reliable when using unpurified ablation samples; however, after extraction, all samples produced PCR products of the expected size. This work expands the sampling capabilities of IR laser ablation, demonstrating that DNA can be isolated from tissue samples for genomic assays. Due to the small size of the ablation regions (1 mm2), this technique will be useful for sampling discrete cell populations from tissue sections. Graphical abstract Infrared laser ablation transfer of intact DNA from a tissue section.
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ADN/análisis , Genómica/métodos , Terapia por Láser/métodos , Animales , Secuencia de Bases , Rayos Infrarrojos , Reacción en Cadena de la Polimerasa/métodos , Ratas , Manejo de EspecímenesRESUMEN
The concentration and size distribution were measured for particles ablated from tissue sections using an infrared optical parametric oscillator laser system. A scanning mobility particle sizer and light scattering particle sizer were used in parallel to realize a particle sizing range from 10 nm to 20 µm. Tissue sections from rat brain and lung ranging in thickness between 10 and 50 µm were mounted on microscope slides and irradiated with nanosecond laser pulses at 3 µm wavelength and fluences between 7 and 21 kJ m(-2) in reflection geometry. The particle size distributions were characterized by a bimodal distribution with a large number of particles 100 nm in diameter and below and a large mass contribution from particles greater than 1 µm in diameter. The large particle contribution dominated the ablated particle mass at high laser fluence. The tissue type, thickness, and water content did not have a significant effect on the particle size distributions. The implications of these results for laser ablation sampling and mass spectrometry imaging under ambient conditions are discussed.
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Rayos Infrarrojos , Terapia por Láser/métodos , Tamaño de la Partícula , Animales , Encéfalo/citología , Encéfalo/metabolismo , Encéfalo/efectos de la radiación , Pulmón/citología , Pulmón/metabolismo , Pulmón/efectos de la radiación , Ratas , Agua/metabolismoRESUMEN
Sampling thin tissue sections with cellular precision can be accomplished using laser ablation microsampling for mass spectrometry analysis. In this work, the use of a pulsed mid-infrared (IR) laser for selecting small regions of interest (ROI) in tissue sections for offline liquid chromatography-tandem mass spectrometry (LC-MS/MS) is described. The laser is focused onto the tissue section, which is rastered as the laser is fired. The ablated tissue is captured in a microwell array and processed in situ through reduction, alkylation, and digestion with a low liquid volume workflow. The resulting peptides from areas as small as 0.01 mm2 containing 5 ng of protein are analyzed for protein identification and quantification using offline LC-MS/MS.
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Terapia por Láser , Espectrometría de Masas en Tándem , Espectrometría de Masas en Tándem/métodos , Terapia por Láser/métodos , Cromatografía Liquida/métodos , Proteómica/métodos , Animales , Humanos , Rayos Infrarrojos , Rayos LáserRESUMEN
We report the biochemical, structural, and functional characterization of the protein coded by gene PA4880 in the P. aeruginosa PAO1 genome. The PA4880 gene had been annotated as coding a probable bacterioferritin. Our structural work shows that the product of gene PA4880 is a protein that adopts the Dps subunit fold, which oligomerizes into a 12-mer quaternary structure. Unlike Dps, however, the ferroxidase di-iron centers and iron coordinating ligands are buried within each subunit, in a manner identical to that observed in the ferroxidase center of P. aeruginosa bacterioferritin. Since these structural characteristics correspond to Dps-like proteins, we term the protein as P. aeruginosa Dps-like, or Pa DpsL. The ferroxidase centers in Pa DpsL catalyze the oxidation of Fe2+ utilizing O2 or H2O2 as oxidant, and the resultant Fe3+ is compartmentalized in the interior cavity. Interestingly, incubating Pa DpsL with plasmid DNA results in efficient nicking of the DNA and at higher concentrations of Pa DpsL the DNA is linearized and eventually degraded. The nickase and endonuclease activities suggest that Pa DpsL, in addition to participating in the defense of P. aeruginosa cells against iron-induced toxicity, may also participate in the innate immune mechanisms consisting of restriction endonucleases and cognate methyl transferases.
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Antioxidant therapies are of interest in the prevention and management of ocular disorders such as cataracts. Although an active area of interest, topical therapy with antioxidants for the treatment of cataracts is complicated by multiple ocular anatomical barriers, product stability, and solubility. Entrapment and delivery of antioxidants with poly(lactic-co-glycolic acid) nanoparticles is a possible solution to these challenges, however, little is known regarding their effects in vitro or in vivo. Our first aim was to investigate the impact of blank and lutein loaded PLGA nanoparticles on viability and development of reactive oxygen species in lens epithelial cells in vitro. Photo-oxidative stress was induced by ultraviolet light exposure with cell viability and reactive oxygen species monitored. Next, an in vivo, selenite model was utilized to induce cataract formation in rodents. Eyes were treated topically with both free lutein and lutein loaded nanoparticles (LNP) at varying concentrations. Eyes were monitored for the development of anterior segment changes and cataract formation. The ability of nanodelivered lutein to reach the anterior segment of the eye was evaluated by liquid chromatography coupled to mass spectrometry of aqueous humor samples and liquid chromatography coupled to tandem mass spectrometry (targeted LC-MS/MS) of lenses. LNP had a minimal impact on the viability of lens epithelial cells during the short exposure timeframe (24 h) and at concentrations < 0.2 µg LNP/µl. A significant reduction in the development of reactive oxygen species was also noted. Animals treated with LNPs at an equivalent lutein concentration of 1,278 µg /mL showed the greatest reduction in cataract scores. Lutein delivery to the anterior segment was confirmed through evaluation of aqueous humor and lens sample evaluation. Topical treatment was not associated with the development of secondary keratitis or anterior uveitis when applied once daily for one week. LNPs may be an effective in the treatment of cataracts.
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Administración Tópica , Catarata , Luteína , Nanopartículas , Copolímero de Ácido Poliláctico-Ácido Poliglicólico , Animales , Luteína/farmacología , Luteína/administración & dosificación , Copolímero de Ácido Poliláctico-Ácido Poliglicólico/química , Nanopartículas/química , Catarata/tratamiento farmacológico , Ratas , Cristalino/efectos de los fármacos , Cristalino/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Estrés Oxidativo/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Antioxidantes/farmacología , Antioxidantes/administración & dosificación , Humanos , Células Epiteliales/efectos de los fármacos , Células Epiteliales/metabolismo , Humor Acuoso/efectos de los fármacos , Humor Acuoso/metabolismo , Masculino , Línea Celular , Ácido Láctico/química , Ácido Poliglicólico/químicaRESUMEN
Lipid metabolism and glycolysis play crucial roles in the progression and metastasis of cancer, and the use of 3-bromopyruvate (3-BP) as an antiglycolytic agent has shown promise in killing pancreatic cancer cells. However, developing an effective strategy to avoid chemoresistance requires the ability to probe the interaction of cancer drugs with complex tumor-associated microenvironments (TAMs). Unfortunately, no robust and multiplexed molecular imaging technology is currently available to analyze TAMs. In this study, the simultaneous profiling of three protein biomarkers using SERS nanotags and antibody-functionalized nanoparticles in a syngeneic mouse model of pancreatic cancer (PC) is demonstrated. This allows for comprehensive information about biomarkers and TAM alterations before and after treatment. These multimodal imaging techniques include surface-enhanced Raman spectroscopy (SERS), immunohistochemistry (IHC), polarized light microscopy, second harmonic generation (SHG) microscopy, fluorescence lifetime imaging microscopy (FLIM), and untargeted liquid chromatography and mass spectrometry (LC-MS) analysis. The study reveals the efficacy of 3-BP in treating pancreatic cancer and identifies drug treatment-induced lipid species remodeling and associated pathways through bioinformatics analysis.
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Neoplasias Pancreáticas , Microambiente Tumoral , Ratones , Animales , Neoplasias Pancreáticas/diagnóstico por imagen , Neoplasias Pancreáticas/tratamiento farmacológico , Microscopía Fluorescente , Biomarcadores , Imagen Multimodal , Espectrometría RamanRESUMEN
Infrared (IR) laser ablation was used to remove localized tissue regions from which proteins were extracted and processed with a low volume sample preparation workflow for bottom-up proteomics by liquid chromatography tandem mass spectrometry (LC-MS/MS). A polytetrafluoroethylene (PTFE) coated glass slide with 2 mm diameter microwells was used to capture ablated rat brain tissue for in situ protein digestion with submicroliter solution volumes. The resulting peptides were analyzed with LC-MS/MS for protein identification and label-free quantification. The method was used to identify an average of 600, 1350, and 1900 proteins from ablation areas of 0.01, 0.04, and 0.1 mm2, respectively, from a 50 µm thick rat brain tissue section. Differential proteomics of 0.01 mm2 regions captured from cerebral cortex and corpus callosum was accomplished to demonstrate the capabilities of the approach.
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Terapia por Láser , Proteómica , Animales , Cromatografía Liquida , Rayos Infrarrojos , Terapia por Láser/métodos , Proteínas/análisis , Proteómica/métodos , Ratas , Espectrometría de Masas en Tándem/métodosRESUMEN
Ferritins are iron storage proteins assembled from 24 subunits into a spherical and hollow structure. The genomes of many bacteria harbor genes encoding two types of ferritin-like proteins, the bacterial ferritins (Ftn) and the bacterioferritins (Bfr), which bind heme. The genome of P. aeruginosa PAO1 (like the genomes of many bacteria) contains genes coding for two different types of ferritin-like molecules, ftnA (PA4235) and bfrB (PA3531). The reasons for requiring the presence of two distinct types of iron storage protein in bacterial cells have remained largely unexplained. Attempts to understand this issue in P. aeruginosa through the recombinant expression of the ftnA and bfrB genes in E. coli host cells, coupled to the biochemical and structural characterization of the recombinant 24-mer FtnA and 24-mer BfrB molecules, have shown that each of the recombinant molecules can form an Fe3+-mineral core. These observations led to the suggestion that 24-mer FtnA and 24-mer BfrB molecules coexist in P. aeruginosa cells where they share iron storage responsibilities. Herein, we demonstrate that P. aeruginosa utilizes a single heterooligomeric 24-mer Bfr assembled from FtnA and BfrB subunits. The relative content of the FtnA and BfrB subunits in Bfr depends on the O2 availability during cell culture, such that Bfr isolated from aerobically cultured P. aeruginosa is assembled from a majority of BfrB subunits. In contrast, when the cells are cultured in O2-limiting conditions, the proportion of FtnA subunits in the isolated Bfr increases significantly and can become the most abundant subunit. Despite the variability in the subunit composition of Bfr, the 24-mer assembly is consistently arranged from FtnA subunit dimers devoid of heme and BfrB subunit dimers each containing a heme molecule.
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Escherichia coli , Pseudomonas aeruginosa , Proteínas Bacterianas/metabolismo , Grupo Citocromo b , Escherichia coli/genética , Escherichia coli/metabolismo , Ferritinas/metabolismo , Hemo/metabolismo , Hierro/metabolismo , Oxígeno/metabolismo , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/metabolismoRESUMEN
A fast and simple HPLC method has been developed and validated for the quantification of a completely new anti-cancer drug during the manufacturing process. The combination of four compounds including α-ketoglutaric acid, hydroxymethylfurfural, N-acetyl-L-methionine and N-acetyl-L-selenomethionine, administered intravenously, is still in test phase but has already shown promising results in cancer therapy. HPLC separation was achieved on an RP-18 column with a gradient system. However, the highly different concentrations of the compounds required a variation in the detection wavelength within one run. In order to produce a chromatogram where peaks were comparable on a similar range scale, detection at absorption maxima for the two most concentrated components was avoided. After optimization of the gradient program it was possible to detect all four substances within 14 min in spite of their strongly different chemical structure. The method developed was validated for accuracy, repeatability, reproducibility and robustness in relation to temperature and pH of buffer. Linearity as well as the limit of detection and quantification were determined. This HPLC method was found to be precise, accurate and reproducible and can be easily used for in-line process control during the manufacture of the anti-tumour infusion solution.
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Antineoplásicos/análisis , Cromatografía Líquida de Alta Presión/métodos , Cromatografía Líquida de Alta Presión/instrumentaciónRESUMEN
Deep-ultraviolet laser ablation with a pulsed 193 nm ArF excimer laser was used to remove localized regions from tissue sections from which proteins were extracted for spatially resolved proteomic analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS). The ability to capture intact proteins by ablation at 193 nm wavelength was verified by matrix-assisted laser desorption ionization (MALDI) of the protein standard bovine serum albumin (BSA), which showed that BSA was ablated and captured without fragmentation. A Bradford assay of the ablated and captured proteins indicated 90% efficiency for transfer of the intact protein at a laser fluence of 3 kJ/m2. Rat brain tissue sections mounted on quartz microscope slides and ablated in transmission mode yielded 2 µg protein per mm2 as quantified by the Bradford assay. Tissue areas ranging from 0.06 mm2 to 1 mm2 were ablated and the ejected material was collected for proteomic analysis. Extracted proteins were digested and the resulting peptides were analyzed by LC-MS/MS. The proteins extracted from the ablated areas were identified and the average number of identified proteins ranged from 85 in the 0.06 mm2 area to 2400 in the 1 mm2 area of a 50 µm thick tissue. In comparison to infrared laser ablation of equivalent sampled areas, both the protein mass and number of proteins identified using DUV laser ablation sampling were approximately four times larger.
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Terapia por Láser , Proteómica , Animales , Bovinos , Cromatografía Liquida , Rayos Infrarrojos , Ratas , Albúmina Sérica Bovina , Espectrometría de Masas en TándemRESUMEN
Heterogeneity in the distribution of nutrients and oxygen gradients during biofilm growth gives rise to changes in phenotype. There has been long term interest in identifying spatial differences during biofilm development including clues that identify chemical heterogeneity. Laser ablation sample transfer (LAST) allows site-specific sampling combined with label free proteomics to distinguish radially and axially resolved proteomes for Pseudomonas aeruginosa biofilms. Specifically, differential protein abundances on oxic vs. anoxic regions of a biofilm were observed by combining LAST with bottom up proteomics. This study reveals a more active metabolism in the anoxic region of the biofilm with respect to the oxic region for this clinical strain of P. aeruginosa, despite this organism being considered an aerobe by nature. Protein abundance data related to cellular acclimations to chemical gradients include identification of glucose catabolizing proteins, high abundance of proteins from arginine and polyamine metabolism, and proteins that could also support virulence and environmental stress mediation in the anoxic region. Finally, the LAST methodology requires only a few mm2 of biofilm area to identify hundreds of proteins.
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Biopelículas/efectos de la radiación , Láseres de Estado Sólido , Proteoma/análisis , Pseudomonas aeruginosa/metabolismo , Manejo de Especímenes/métodos , Proteínas Bacterianas/metabolismo , Biopelículas/crecimiento & desarrollo , Cromatografía Líquida de Alta Presión , Cemento de Policarboxilato/química , Proteómica/métodos , Pseudomonas aeruginosa/fisiología , Manejo de Especímenes/instrumentación , Espectrometría de Masas en TándemRESUMEN
Alpha-ketoglutaric acid (alpha-KG) and 5-hydroxymethylfurfural (5-HMF) are currently under investigation as promising cancer cell damaging agents. A method for the simultaneous quantitative determination of alpha-KG and 5-HMF in human plasma was established for screening these compounds in human plasma. Plasma samples were directly treated with O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine hydrochloride to form the corresponding oximes, thus facilitating subsequent liquid-liquid extraction. After formation of the trimethylsilyl ethers, samples were analyzed by gas chromatography with electron ionization mass spectrometry. Stable isotope labeled standards were used, the preparation of (13)C(6)-5-HMF is described. Limits of quantitation were set to 0.938 microg/mL for alpha-KG and 0.156 microg/mL for 5-HMF. Inter-day accuracy was < or = 93.7% (alpha-KG) and < or = 92.8% (5-HMF). Inter-day precision was < or = 6.0% (alpha-KG) and < or = 4.6% (5-HMF). The method has been successfully applied to pharmacokinetic profiling of the compounds after intravenous application.
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Análisis Químico de la Sangre/métodos , Furaldehído/análogos & derivados , Cromatografía de Gases y Espectrometría de Masas/métodos , Ácidos Cetoglutáricos/sangre , Antineoplásicos/sangre , Mezclas Complejas/análisis , Furaldehído/sangre , Humanos , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
Iron homeostasis offers a significant bacterial vulnerability because pathogens obtain essential iron from their mammalian hosts, but host-defenses maintain vanishingly low levels of free iron. Although pathogens have evolved mechanisms to procure host-iron, these depend on well-regulated iron homeostasis. To disrupt iron homeostasis, our work has targeted iron mobilization from the iron storage protein bacterioferritin (BfrB) by blocking a required interaction with its cognate ferredoxin partner (Bfd). The blockade of the BfrB-Bfd complex by deletion of the bfd gene (Δbfd) causes iron to irreversibly accumulate in BfrB. In this study we used mass spectrometry and NMR spectroscopy to compare the proteomic response and the levels of key intracellular metabolites between wild type (wt) and isogenic ΔbfdP. aeruginosa strains. We find that the irreversible accumulation of unusable iron in BfrB leads to acute intracellular iron limitation, even if the culture media is iron-sufficient. Importantly, the iron limitation and concomitant iron metabolism dysregulation trigger a cascade of events that lead to broader metabolic homeostasis disruption, which includes sulfur limitation, phenazine-mediated oxidative stress, suboptimal amino acid synthesis and altered carbon metabolism.
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A multimodal workflow for mass spectrometry imaging was developed that combines MALDI imaging with protein identification and quantification by liquid chromatography tandem mass spectrometry (LC-MS/MS). Thin tissue sections were analyzed by MALDI imaging, and the regions of interest (ROI) were identified using a smoothing and edge detection procedure. A midinfrared laser at 3-µm wavelength was used to remove the ROI from the brain tissue section after MALDI mass spectrometry imaging (MALDI MSI). The captured material was processed using a single-pot solid-phase-enhanced sample preparation (SP3) method and analyzed by LC-MS/MS using ion mobility (IM) enhanced data independent acquisition (DIA) to identify and quantify proteins; more than 600 proteins were identified. Using a modified database that included isoform and the post-translational modifications chain, loss of the initial methionine, and acetylation, 14 MALDI MSI peaks were identified. Comparison of the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of the identified proteins was achieved through an evolutionary relationships classification system.