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1.
Cell ; 165(6): 1507-1518, 2016 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-27180907

RESUMO

Tools capable of imaging and perturbing mechanical signaling pathways with fine spatiotemporal resolution have been elusive, despite their importance in diverse cellular processes. The challenge in developing a mechanogenetic toolkit (i.e., selective and quantitative activation of genetically encoded mechanoreceptors) stems from the fact that many mechanically activated processes are localized in space and time yet additionally require mechanical loading to become activated. To address this challenge, we synthesized magnetoplasmonic nanoparticles that can image, localize, and mechanically load targeted proteins with high spatiotemporal resolution. We demonstrate their utility by investigating the cell-surface activation of two mechanoreceptors: Notch and E-cadherin. By measuring cellular responses to a spectrum of spatial, chemical, temporal, and mechanical inputs at the single-molecule and single-cell levels, we reveal how spatial segregation and mechanical force cooperate to direct receptor activation dynamics. This generalizable technique can be used to control and understand diverse mechanosensitive processes in cell signaling. VIDEO ABSTRACT.


Assuntos
Técnicas Genéticas , Mecanotransdução Celular , Nanopartículas Metálicas , Receptores Notch/metabolismo , Actinas/metabolismo , Caderinas/metabolismo , Linhagem Celular , Células Cultivadas , Humanos , Mecanorreceptores/fisiologia , Nanopartículas Metálicas/química , Microesferas , Técnicas de Sonda Molecular , Proteínas Recombinantes de Fusão/metabolismo , Análise Espacial , Tempo
3.
Sensors (Basel) ; 24(4)2024 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-38400413

RESUMO

Chemosensor technology for trace gases in the air always aims to identify these compounds and then measure their concentrations. For identification, traceable methods are sparse and relate to large appliances such as mass spectrometers. We present a new method that uses the alternative traceable measurement of the ionization energies of trace gases in a way that can be miniaturized and energetically tuned. We investigate the achievable performance. Since tunable UV sources are not available for photoionization, we take a detour via impact ionization with electrons, which we generate using the photoelectric effect and bring to sharp, defined energies on a nanoscale in the air. Electron impact ionization is thus possible at air pressures of up to 900 hPa. The sensitivity of the process reaches 1 ppm and is equivalent to that of classic PID. With sharpened energy settings, substance identification is currently possible with an accuracy of 30 meV. We can largely explain the experimental observations with the known quantum mechanical models.

4.
Angew Chem Int Ed Engl ; : e202414537, 2024 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-39324525

RESUMO

The 5' cap structure is crucial to mRNA function, with its diverse methylation patterns depending on the cellular state. Sensitive analytical methods are sought after to quantify this cap variety also referred to as cap epitranscriptome. To address a bottleneck for accurate and precise quantitation, we report a facile and fast access to high-quality synthetic standards via a new route, involving P(III)-amidite chemistry. A range of cap nucleotides and their stable heavy isotopic labeled analogues were derived from nucleoside diphosphates, which themselves were directly prepared in a one-step reaction sequence starting from unprotected nucleosides using a triphosphorylating reagent in combination with ethylenediamine. Considering a wider scope, the route also enables direct access to magic spot nucleotides and diphosphates of isoprenyl-alcohols. Stable-isotope labeled cap nucleotides derived from this route paved the way for the development of a highly sensitive LC-MS/MS method, applied to the characterization of mouse brain cap epitranscriptomes, which turned out to be very different from those of cultured cell lines of widespread use in the life sciences.

5.
J Am Chem Soc ; 145(29): 16081-16089, 2023 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-37437195

RESUMO

Magic spot nucleotides (p)ppGpp are important signaling molecules in bacteria and plants. In the latter, RelA-SpoT homologue (RSH) enzymes are responsible for (p)ppGpp turnover. Profiling of (p)ppGpp is more difficult in plants than in bacteria due to lower concentrations and more severe matrix effects. Here, we report that capillary electrophoresis mass spectrometry (CE-MS) can be deployed to study (p)ppGpp abundance and identity in Arabidopsis thaliana. This goal is achieved by combining a titanium dioxide extraction protocol and pre-spiking with chemically synthesized stable isotope-labeled internal reference compounds. The high sensitivity and separation efficiency of CE-MS enables monitoring of changes in (p)ppGpp levels in A. thaliana upon infection with the pathogen Pseudomonas syringae pv. tomato (PstDC3000). We observed a significant increase of ppGpp post infection that is also stimulated by the flagellin peptide flg22 only. This increase depends on functional flg22 receptor FLS2 and its interacting kinase BAK1 indicating that pathogen-associated molecular pattern (PAMP) receptor-mediated signaling controls ppGpp levels. Transcript analyses showed an upregulation of RSH2 upon flg22 treatment and both RSH2 and RSH3 after PstDC3000 infection. Arabidopsis mutants deficient in RSH2 and RSH3 activity display no ppGpp accumulation upon infection and flg22 treatment, supporting the involvement of these synthases in PAMP-triggered innate immune responses to pathogens within the chloroplast.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Guanosina Pentafosfato , Proteínas de Arabidopsis/metabolismo , Transdução de Sinais , Plantas , Cloroplastos/metabolismo
6.
Z Gastroenterol ; 61(11): 1518-1525, 2023 Nov.
Artigo em Alemão | MEDLINE | ID: mdl-37944910

RESUMO

The humanized monoclonal anti-α4ß7-integrin-antibody vedolizumab is one of several biologic therapeutic options in moderate-to-severe ulcerative colitis and Crohn's disease. Within the VISIBLE trial program, a novel subcutaneous application route was evaluated in addition to the already established intravenous form. In this position statement, the working group "Inflammatory Bowel Diseases" of the Austrian Society for Gastroenterology and Hepatology (OEGGH) summarizes the evidence regarding the subcutaneous application of vedolizumab. This work supplements a position paper on the value of vedolizumab as a first-line biologic that has already been published and offers useful recommendations for clinical practice.


Assuntos
Produtos Biológicos , Colite Ulcerativa , Gastroenterologia , Doenças Inflamatórias Intestinais , Humanos , Áustria , Doenças Inflamatórias Intestinais/tratamento farmacológico , Colite Ulcerativa/tratamento farmacológico , Produtos Biológicos/uso terapêutico , Fármacos Gastrointestinais/uso terapêutico
7.
Acc Chem Res ; 54(21): 4036-4050, 2021 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-34648267

RESUMO

Much like linear, branched, and cyclic alkanes, condensed phosphates exist as linear, branched, and cyclic structures. Inasmuch as alkanes are the cornerstone of organic chemistry, generating an inexplorably large chemical space, a comparable richness in structures can be expected for condensed phosphates, as also for them the concepts of isomerism apply. Little of their chemical space has been charted, and only a few different synthesis methods are available to construct isomers of condensed phosphates. Here, we will discuss the application of phosphoramidites with one, two, or three P-N bonds that can be substituted selectively to access different condensed phosphates in a highly controllable manner. Work directed toward the further exploration of this chemical space will contribute to our understanding of the fundamental chemistry of phosphates.In biology, condensed phosphates play important roles in the form of inorganic representatives, such as pyrophosphate, polyphosphate, and cyclophosphate, and also in conjugation with organic molecules, such as esters and amidates. Phosphorus is one of the six biogenic elements; the omnipresence of phosphates in biology points toward their critical involvement in prebiotic chemistry and the emergence of life itself. Indeed, it is hard to imagine any life without phosphate. It is therefore desirable to achieve through synthesis a better understanding of the chemistry of the condensed phosphates to further explore their biology.There is a rich but underexplored chemistry of the family of condensed phosphates per se, which is further diversified by their conjugation to important biomolecules and metabolites. For example, proteins may be polyphosphorylated on lysins, a very recent addition to posttranslational modifications. Adenosine triphosphate, as a representative of the small molecules, on the other hand, is well known as the universal cellular energy currency. In this Account, we will describe our motivations and our approaches to construct, modify, and synthetically apply different representatives of the condensed phosphates. We also describe the generation of hybrids composed of cyclic and linear structures of different oxidation states and develop them into reagents of great utility. A pertinent example is provided in the step-economic synthesis of the magic spot nucleotides (p)ppGpp. Finally, we provide an overview of 31P NMR data collected over the years in our laboratories, helping as a waymarker for not getting lost in condensation.

8.
Angew Chem Int Ed Engl ; 61(1): e202113231, 2022 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-34727582

RESUMO

Condensed phosphates are a critically important class of molecules in biochemistry. Non-natural analogues are important for various applications, such as single-molecule real-time DNA sequencing. Often, such analogues contain more than three phosphate units in their oligophosphate chain. Consequently, investigations into phosphate reactivity enabling new ways of phosphate functionalization and oligophosphorylation are essential. Here, we scrutinize the potential of phosphates to act as arynophiles, paving the way for follow-up oligophosphorylation reactions. The aryne phosphate reaction is a powerful tool to-depending on the perspective-(oligo)phosphorylate arenes or arylate (oligo-cyclo)phosphates. Based on Kobayashi-type o-silylaryltriflates, the aryne phosphate reaction enables rapid entry into a broad spectrum of arylated products, like monophosphates, diphosphates, phosphodiesters and polyphosphates. The synthetic potential of these new transformations is demonstrated by efficient syntheses of nucleotide analogues and an unprecedented one-flask octaphosphorylation.

9.
Angew Chem Int Ed Engl ; 61(5): e202112457, 2022 01 26.
Artigo em Inglês | MEDLINE | ID: mdl-34734451

RESUMO

Stable isotope labelling is state-of-the-art in quantitative mass spectrometry, yet often accessing the required standards is cumbersome and very expensive. Here, a unifying synthetic concept for 18 O-labelled phosphates is presented, based on a family of modified 18 O2 -phosphoramidite reagents. This toolbox offers access to major classes of biologically highly relevant phosphorylated metabolites as their isotopologues including nucleotides, inositol phosphates, -pyrophosphates, and inorganic polyphosphates. 18 O-enrichment ratios >95 % and good yields are obtained consistently in gram-scale reactions, while enabling late-stage labelling. We demonstrate the utility of the 18 O-labelled inositol phosphates and pyrophosphates by assignment of these metabolites from different biological matrices. We demonstrate that phosphate neutral loss is negligible in an analytical setup employing capillary electrophoresis electrospray ionisation triple quadrupole mass spectrometry.


Assuntos
Compostos Organofosforados
10.
Angew Chem Int Ed Engl ; 61(22): e202201731, 2022 05 23.
Artigo em Inglês | MEDLINE | ID: mdl-35294098

RESUMO

Magic Spot Nucleotides (MSN) regulate the stringent response, a highly conserved bacterial stress adaptation mechanism, enabling survival under adverse external challenges. In times of antibiotic crisis, a detailed understanding of stringent response is essential, as potentially new targets for pharmacological intervention could be identified. In this study, we delineate the MSN interactome in Escherichia coli and Salmonella typhimurium applying a family of trifunctional photoaffinity capture compounds. We introduce MSN probes covering a diverse phosphorylation pattern, such as pppGpp, ppGpp, and pGpp. Our chemical proteomics approach provides datasets of putative MSN receptors both from cytosolic and membrane fractions that unveil new MSN targets. We find that the activity of the non-Nudix hydrolase ApaH is potently inhibited by pppGpp, which itself is converted to pGpp by ApaH. The capture compounds described herein will be useful to identify MSN interactomes across bacterial species.


Assuntos
Regulação Bacteriana da Expressão Gênica , Guanosina Pentafosfato , Bactérias/metabolismo , Proteínas de Bactérias/metabolismo , Guanosina Tetrafosfato , Nucleotídeos
11.
J Org Chem ; 85(22): 14496-14506, 2020 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-32502348

RESUMO

The complex phosphorylation pattern of natural and modified pentaphosphorylated magic spot nucleotides is generated in a highly efficient way. A cyclic pyrophosphoryl phosphoramidite (cPyPA) reagent is used to introduce four phosphates on nucleosides regioselectively in a one-flask key transformation. The obtained magic spot nucleotides are used to develop a capillary electrophoresis UV detection method, enabling nucleotide assignment in complex bacterial extracts.

12.
Molecules ; 25(22)2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-33203096

RESUMO

Photocages have been successfully applied in cellular signaling studies for the controlled release of metabolites with high spatio-temporal resolution. Commonly, coumarin photocages are activated by UV light and the quantum yields of uncaging are relatively low, which can limit their applications in vivo. Here, syntheses, the determination of the photophysical properties, and quantum chemical calculations of 7-diethylamino-4-hydroxymethyl-thiocoumarin (thio-DEACM) and caged adenine nucleotides are reported and compared to the widely used 7-diethylamino-4-hydroxymethyl-coumarin (DEACM) caging group. In this comparison, thio-DEACM stands out as a phosphate cage with improved photophysical properties, such as red-shifted absorption and significantly faster photolysis kinetics.


Assuntos
Cumarínicos/química , Luz , Nucleotídeos/química , Fenômenos Físicos , Trifosfato de Adenosina/química , Fluorescência , Fotólise
13.
J Am Chem Soc ; 141(38): 15013-15017, 2019 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-31512870

RESUMO

Phosphoramidite analogues of modified cyclotriphosphates provide a general and step-economical synthesis of nucleoside triphosphates and analogues on scale without the need for protecting groups. These reagents enable rapid access to pure nucleoside oligophosphates and a range of other analogues that were previously difficult to obtain (e.g., NH, CH2, CCl2, and CF2 replacements for O, phosphono- and phosphoimidazolides, -morpholidates, -azidates, and -fluoridates). DFT calculations demonstrate that the selectivity of the cyclotriphosphate opening reactions proceeds via an in-line substitution mechanism that displaces the least charged leaving group.

14.
Clin Gastroenterol Hepatol ; 16(7): 992-1002.e6, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29559361

RESUMO

Despite guidelines for detection and treatment of Helicobacter pylori infection, recommendations to test patients before and after therapy are commonly not followed in the United States. At the Houston Consensus Conference, 11 experts on management of adult and pediatric patients with H pylori, from different geographic regions of the United States, met to discuss key factors in diagnosis of H pylori infection, including identification of appropriate patients for testing, effects of antibiotic susceptibility on testing and treatment, appropriate methods for confirmation of infection and eradication, and relevant health system considerations. The experts divided into groups that used a modified Delphi panel approach to assess appropriate patients for testing, testing for antibiotic susceptibility and treatment, and test methods and confirmation of eradication. The quality of evidence and strength of recommendations were evaluated using the GRADE system. The results of the individual workshops were presented for a final consensus vote by all panel members. After the Expert Consensus Development meeting, the conclusions were validated by a separate panel of gastroenterologists, who assessed their level of agreement with each of the 29 statements developed at the Expert Consensus Development. The final recommendations are provided, on the basis of the best available evidence, and provide consensus statements with supporting literature to implement testing for H pylori infection at health care systems across the United States.


Assuntos
Testes Diagnósticos de Rotina/métodos , Infecções por Helicobacter/diagnóstico , Helicobacter pylori/isolamento & purificação , Infecções por Helicobacter/tratamento farmacológico , Helicobacter pylori/efeitos dos fármacos , Humanos , Estados Unidos
15.
Org Biomol Chem ; 16(43): 8030-8033, 2018 11 07.
Artigo em Inglês | MEDLINE | ID: mdl-30334043

RESUMO

A three-step one-pot biocatalytic cascade was designed for the enantioselective formal α-amination of hexanoic acid to l-norleucine. Regioselective hydroxylation by P450CLA peroxygenase to 2-hydroxyhexanoic acid was followed by oxidation to the ketoacid by two stereocomplementary dehydrogenases. Combination with final stereoselective reductive amination by amino acid dehydrogenase furnished l-norleucine in >97% ee.


Assuntos
Biocatálise , Caproatos/química , Sistema Enzimático do Citocromo P-450/metabolismo , Norleucina/química , Aminação , Bactérias/enzimologia , Estereoisomerismo , Especificidade por Substrato
16.
Angew Chem Int Ed Engl ; 57(2): 427-430, 2018 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-29125663

RESUMO

The functionalization of bio-based chemicals is essential to allow valorization of natural carbon sources. An atom-efficient biocatalytic oxidative cascade was developed for the conversion of saturated fatty acids to α-ketoacids. Employment of P450 monooxygenase in the peroxygenase mode for regioselective α-hydroxylation of fatty acids combined with enantioselective oxidation by α-hydroxyacid oxidase(s) resulted in internal recycling of the oxidant H2 O2 , thus minimizing degradation of ketoacid product and maximizing biocatalyst lifetime. The O2 -dependent cascade relies on catalytic amounts of H2 O2 and releases water as sole by-product. Octanoic acid was converted under mild conditions in aqueous buffer to 2-oxooctanoic acid in a simultaneous one-pot two-step cascade in up to >99 % conversion without accumulation of hydroxyacid intermediate. Scale-up allowed isolation of final product in 91 % yield and the cascade was applied to fatty acids of various chain lengths (C6:0 to C10:0).

17.
J Neural Transm (Vienna) ; 124(6): 715-720, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28247031

RESUMO

Treatment of patients with Parkinson's disease in specialized units is quite common in Germany. Data on the benefit of this hospitalization of patients with Parkinson's disease on motor and non-motor symptoms in conjunction with standardized tests are rare. Objective was to determine the efficacy of this therapeutic setting. We scored disease severity and performed clinical tests, respectively, instrumental procedures under standardized conditions in consecutively referred in-patients initially and at the end of their hospital stay. There was a decrease of motor and non-motor symptoms. The extent of improvement of non-motor and motor symptoms correlated to each other. Performance of complex movement sequences became better, whereas execution of simple movement series did not ameliorate. The interval for the timed up and go test went down. We demonstrate the effectiveness of an in-patient stay in a specialized unit for Parkinson's disease. Objective standardized testing supplements subjective clinical scoring with established rating scales.


Assuntos
Hospitalização , Atividade Motora , Doença de Parkinson/terapia , Idoso , Feminino , Humanos , Pacientes Internados , Masculino , Doença de Parkinson/diagnóstico , Doença de Parkinson/fisiopatologia , Índice de Gravidade de Doença , Resultado do Tratamento
18.
Org Biomol Chem ; 14(24): 5673-82, 2016 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-26806535

RESUMO

The titanium(iii)-catalysed cross-selective reductive umpolung of Michael-acceptors represents a unique direct conjugate ß-alkylation reaction. It allows the cross-selective preparation of 1,6- and 1,4-difunctionalised building blocks without the requirement of stoichiometric organometallic reagents. In this full paper, the development and scope of the titanium(iii)-catalysed cross-selective reductive umpolung of Michael-acceptors is described. Based on the observed selectivities and additional mechanistic experiments a refined mechanistic proposal is presented.

19.
Biochemistry ; 54(6): 1408-20, 2015 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-25613106

RESUMO

The broad recognition specificity exhibited by integrin α(M)ß2 (Mac-1, CD11b/CD18) has allowed this adhesion receptor to play innumerable roles in leukocyte biology, yet we know little about how and why α(M)ß2 binds its multiple ligands. Within α(M)ß2, the α(M)I-domain is responsible for integrin's multiligand binding properties. To identify its recognition motif, we screened peptide libraries spanning sequences of many known protein ligands for α(M)I-domain binding and also selected the α(M)I-domain recognition sequences by phage display. Analyses of >1400 binding and nonbinding peptides derived from peptide libraries showed that a key feature of the α(M)I-domain recognition motif is a small core consisting of basic amino acids flanked by hydrophobic residues. Furthermore, the peptides selected by phage display conformed to a similar pattern. Identification of the recognition motif allowed the construction of an algorithm that reliably predicts the α(M)I-domain binding sites in the α(M)ß2 ligands. The recognition specificity of the α(M)I-domain resembles that of some chaperones, which allows it to bind segments exposed in unfolded proteins. The disclosure of the α(M)ß2 binding preferences allowed the prediction that cationic host defense peptides, which are strikingly enriched in the α(M)I-domain recognition motifs, represent a new class of α(M)ß2 ligands. This prediction has been tested by examining the interaction of α(M)ß2 with the human cathelicidin peptide LL-37. LL-37 induced a potent α(M)ß2-dependent cell migratory response and caused activation of α(M)ß2 on neutrophils. The newly revealed recognition specificity of α(M)ß2 toward unfolded protein segments and cationic proteins and peptides suggests that α(M)ß2 may serve as a previously proposed "alarmin" receptor with important roles in innate host defense.


Assuntos
Antígeno de Macrófago 1/metabolismo , Sequência de Aminoácidos , Sítios de Ligação , Humanos , Ligantes , Antígeno de Macrófago 1/química , Antígeno de Macrófago 1/fisiologia , Dados de Sequência Molecular , Conformação Proteica
20.
Chemistry ; 21(6): 2339-42, 2015 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-25476744

RESUMO

A sequence of two titanium(III)-catalyzed reductive umpolung reactions is reported that allows the rapid construction of benzazo- and benzoxozine building blocks. The first step is a reductive cross-coupling of quinolones or chromones with Michael acceptors. This reaction proceeds with complete syn-selectivity for the quinolone functionalization while the anti-diastereomers are obtained as the major products from chromones. With different reaction conditions, the stereochemical outcome can be altered to afford the syn-chromanone products as well. A subsequent reductive ketyl radical cyclization forges the tricyclic title compounds in good yields. A stereochemical model explaining the observed stereoselectivities is provided and the product configurations were unambiguously verified by X-ray analyses and 2D NMR spectroscopic experiments.


Assuntos
Oxocinas/química , Titânio/química , Catálise , Cromonas/química , Cristalografia por Raios X , Ciclização , Conformação Molecular , Oxocinas/síntese química , Estereoisomerismo
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