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1.
Nat Commun ; 11(1): 4714, 2020 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-32948754

RESUMO

The application of forces and torques on the single molecule level has transformed our understanding of the dynamic properties of biomolecules, but rare intermediates have remained difficult to characterize due to limited throughput. Here, we describe a method that provides a 100-fold improvement in the throughput of force spectroscopy measurements with topological control, which enables routine imaging of 50,000 single molecules and a 100 million reaction cycles in parallel. This improvement enables detection of rare events in the life cycle of the cell. As a demonstration, we characterize the supercoiling dynamics and drug-induced DNA break intermediates of topoisomerases. To rapidly quantify distinct classes of dynamic behaviors and rare events, we developed a software platform with an automated feature classification pipeline. The method and software can be readily adapted for studies of a broad range of complex, multistep enzymatic pathways in which rare intermediates have escaped classification due to limited throughput.


Assuntos
DNA/química , Fenômenos Magnéticos , Magnetismo/métodos , Nanotecnologia , Análise Espectral/métodos , Ciprofloxacino/farmacologia , DNA/efeitos dos fármacos , Quebras de DNA/efeitos dos fármacos , Conformação de Ácido Nucleico , Pinças Ópticas , Fenômenos Físicos , Software
2.
Proc Natl Acad Sci U S A ; 117(37): 23158-23164, 2020 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-32868421

RESUMO

The recently discovered, chlorophyll-f-containing, far-red photosystem II (FR-PSII) supports far-red light photosynthesis. Participation and kinetics of spectrally shifted far-red pigments are directly observable and separated from that of bulk chlorophyll-a We present an ultrafast transient absorption study of FR-PSII, investigating energy transfer and charge separation processes. Results show a rapid subpicosecond energy transfer from chlorophyll-a to the long-wavelength chlorophylls-f/d The data demonstrate the decay of an ∼720-nm negative feature on the picosecond-to-nanosecond timescales, coinciding with charge separation, secondary electron transfer, and stimulated emission decay. An ∼675-nm bleach attributed to the loss of chl-a absorption due to the formation of a cation radical, PD1 +•, is only fully developed in the nanosecond spectra, indicating an unusually delayed formation. A major spectral feature on the nanosecond timescale at 725 nm is attributed to an electrochromic blue shift of a FR-chlorophyll among the reaction center pigments. These time-resolved observations provide direct experimental support for the model of Nürnberg et al. [D. J. Nürnberg et al., Science 360, 1210-1213 (2018)], in which the primary electron donor is a FR-chlorophyll and the secondary donor is chlorophyll-a (PD1 of the central chlorophyll pair). Efficient charge separation also occurs using selective excitation of long-wavelength chlorophylls-f/d, and the localization of the excited state on P720* points to a smaller (entropic) energy loss compared to conventional PSII, where the excited state is shared over all of the chlorin pigments. This has important repercussions on understanding the overall energetics of excitation energy transfer and charge separation reactions in FR-PSII.


Assuntos
Clorofila/metabolismo , Transferência de Energia/fisiologia , Fotossíntese/fisiologia , Complexo de Proteína do Fotossistema II/metabolismo , Transporte de Elétrons/fisiologia , Cinética , Luz , Análise Espectral/métodos
3.
Food Chem ; 331: 127361, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32650229

RESUMO

A low cost hand-held spectral analytical system was developed for in situ screening of phenolics and flavonoids in puff dried Ziziphus jujuba (Z. Jujuba) samples. Standards of gallic acid, caffeic acid, l-epicatechin, phloridzin and cianidanol were used to quantify the individual phenolics and flavonoids using high performance liquid chromatography-diode array detector (HPLC-DAD). The synergy interval partial least square with ant colony optimization (Si-ACO-PLS) was attempted to optimize and capture informative variables for the prediction of target compounds. The model performance was evaluated using correlation coefficients of prediction (Rp); root mean square error of prediction (RMSEP) and residual predictive deviation (RPD). The Si-ACO-PLS yielded optimal performance, 0.8540 ≤ Rc ≤ 0.9250, 0.8360 ≤ Rp ≤ 0.9056, 0.84 ≤ RMSEP ≤ 16.30 and 2.03 ≤ RPD ≤ 2.26. The hand-held spectral analytical system coupled with Si-ACO-PLS proved to the reliable, rapid and cost-effective method to quantify the phenolics and flavonoids in Z. Jujuba.


Assuntos
Flavonoides/análise , Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Fenóis/análise , Ziziphus/química , Algoritmos , Cromatografia Líquida de Alta Pressão , Dessecação/métodos , Análise de Alimentos/estatística & dados numéricos , Análise dos Mínimos Quadrados , Análise Espectral/instrumentação , Análise Espectral/métodos
4.
Nat Protoc ; 15(7): 2143-2162, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32555465

RESUMO

Vibrational spectroscopy techniques, such as Fourier-transform infrared (FTIR) and Raman spectroscopy, have been successful methods for studying the interaction of light with biological materials and facilitating novel cell biology analysis. Spectrochemical analysis is very attractive in disease screening and diagnosis, microbiological studies and forensic and environmental investigations because of its low cost, minimal sample preparation, non-destructive nature and substantially accurate results. However, there is now an urgent need for multivariate classification protocols allowing one to analyze biologically derived spectrochemical data to obtain accurate and reliable results. Multivariate classification comprises discriminant analysis and class-modeling techniques where multiple spectral variables are analyzed in conjunction to distinguish and assign unknown samples to pre-defined groups. The requirement for such protocols is demonstrated by the fact that applications of deep-learning algorithms of complex datasets are being increasingly recognized as critical for extracting important information and visualizing it in a readily interpretable form. Hereby, we have provided a tutorial for multivariate classification analysis of vibrational spectroscopy data (FTIR, Raman and near-IR) highlighting a series of critical steps, such as preprocessing, data selection, feature extraction, classification and model validation. This is an essential aspect toward the construction of a practical spectrochemical analysis model for biological analysis in real-world applications, where fast, accurate and reliable classification models are fundamental.


Assuntos
Análise Espectral/métodos , Estatística como Assunto/métodos , Vibração , Animais , Humanos , Análise Multivariada , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman
5.
Food Chem ; 331: 127051, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32569974

RESUMO

A simple, fast, and efficient spark discharge-laser-induced breakdown spectroscopy (SD-LIBS) method was developed for determining rice botanic origin using predictive modeling based on support vector machine (SVM). Seventy-two samples from four rice varieties (Guri, Irga 424, Puitá, and Taim) were analyzed by SD-LIBS. Spectral lines of C, Ca, Fe, Mg, N and Na were selected as input variables for prediction model fitting. The SVM algorithm parameters were optimized using a central composite design (CCD) to find the better classification performance. The optimum model for discriminating rice samples according to their botanical variety was obtained using C = 5.25 and γ = 0.119. This model achieved 96.4% of correct predictions in test samples and showed sensitivities and specificities per class within the range of 92-100%. The developed method is robust and eco-friendly for rice botanic identification since its prediction results are consistent and reproducible and its application does not generate chemical waste.


Assuntos
Análise de Alimentos/métodos , Oryza/química , Análise Espectral/métodos , Algoritmos , Análise de Alimentos/instrumentação , Análise de Alimentos/estatística & dados numéricos , Lasers , Aprendizado de Máquina , Metais/análise , Sensibilidade e Especificidade , Análise Espectral/instrumentação , Análise Espectral/estatística & dados numéricos , Máquina de Vetores de Suporte
6.
J Breath Res ; 14(4): 047102, 2020 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-32531773

RESUMO

The fraction of exhaled nitric oxide (FENO) is an important biomarker for the diagnosis and management of asthma and other pulmonary diseases associated with airway inflammation. In this study we report on a novel method for accurate, highly time-resolved, real time detection of FENO at the mouth. The experimental arrangement is based on a combination of optical sensors for the determination of the temporal profile of exhaled NO and CO2 concentrations. Breath CO2 and exhalation flow are measured at the mouth using diode laser absorption spectroscopy (at 2 µm) and differential pressure sensing, respectively. NO is determined in a sidestream configuration using a quantum cascade laser based, cavity-enhanced absorption cell (at 5.2 µm) which simultaneously measures sidestream CO2. The at-mouth and sidestream CO2 measurements are used to enable the deconvolution of the sidestream NO measurement back to the at-mouth location. All measurements have a time resolution of 0.1 s, limited by the requirement of a reasonable limit of detection for the NO measurement, which on this timescale is 4.7 ppb (2 σ). Using this methodology, NO expirograms (FENOgrams) were measured and compared for eight healthy volunteers. The FENOgrams appear to differ qualitatively between individuals and the hope is that the dynamic information encoded in these FENOgrams will provide valuable additional insight into the location of the inflammation in the airways and potentially predict a response to therapy. A validation of the measurements at low-time resolution is provided by checking that results from previous studies that used a two-compartment model of NO production can be reproduced using our technology.


Assuntos
Testes Respiratórios/métodos , Fenômenos Ópticos , Análise Espectral/métodos , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
7.
AAPS PharmSciTech ; 21(5): 179, 2020 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-32596747

RESUMO

Coating process is a critical unit operation for manufacturing solid oral dosage forms. For a long time, the coating weight gain has been discerned as the most important, if not only, characteristic describing the coating quality. As the introduction of quality by design (QbD) and advancement of process analytical technology (PAT), nowadays more techniques are available to analyze other quality attributes which have been overlooked but have substantial impacts on the performance of coated products. The techniques that permit rapid and non-destructive measurements are of particular importance to improve process operation and product quality. This article reviews the analytical techniques that have been and potentially could be used as PAT tools for characterizing the quality of pharmaceutical coating product. By identifying the challenges and pitfalls encountered during PAT application, the review aims at fostering the adoption of PAT for paving the way to enhanced quality and efficiency of the coating processes.


Assuntos
Tecnologia Farmacêutica/métodos , Preparações Farmacêuticas , Análise Espectral/métodos
8.
Chemosphere ; 253: 126684, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32464772

RESUMO

The use of Fusarium solani fungi in an expanded perlite packed biofilter was investigated for the treatment of a hexane polluted waste gas stream using selected ion flow tube mass spectrometry (SIFT-MS). The latter analytical technique proved to be of utmost importance to evaluate the performance of the biofilter at high time resolution (seconds) under various transient conditions, analogous to industrial situations. The biofilter was operational for 277 days with inlet loads varying between 1 and 14 g m-3 h-1 and applying an empty bed residence time of 116 s. The results showed a positive behaviour of the biofilter against different types of disruptions such as: (i) changes in the relative humidity of the inlet gas, (ii) stopping the carbon supply for 1, 5 and 10 days, (iii) varying the inlet hexane concentration (step increases and intermittent pulses) and (iv) limiting the availability of nutrients. X-ray imaging (both conventional 2D µCT and X-ray fluorescence, XRF) was applied for the first time on biofilter media in order to get insight in the internal structure of expanded perlite and to visualise the biomass growth. The latter in combination with online porosity measurements using SIFT-MS provides fundamental information regarding the biofiltration process.


Assuntos
Óxido de Alumínio , Poluentes Ambientais/isolamento & purificação , Filtração/métodos , Fungos , Hexanos/isolamento & purificação , Dióxido de Silício , Poluentes Atmosféricos/isolamento & purificação , Biodegradação Ambiental , Biomassa , Fusarium/crescimento & desenvolvimento , Fusarium/metabolismo , Análise Espectral/métodos
9.
Phys Chem Chem Phys ; 22(19): 10934-10940, 2020 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-32373844

RESUMO

The structure of interfacial water determines atmospheric chemistry, wetting properties of materials, and protein folding. The challenge of investigating the properties of specific interfacial water molecules has frequently been confronted using surface-specific sum-frequency generation (SFG) vibrational spectroscopy using the O-H stretch mode. While perfectly suited for the water-air interface, for complex interfaces, a potential complication arises from the contribution of hydroxyl or amine groups of non-water species present at the surface, such as surface hydroxyls on minerals, or O-H and N-H groups contained in proteins. Here, we present a protocol to extract the hydrogen bond strength selectively of interfacial water, through the water bending mode. The bending mode vibrational frequency distribution provides a new avenue for unveiling the hydrogen bonding structure of interfacial water at complex aqueous interfaces. We demonstrate this method for the water-CaF2 and water-protein interfaces. For the former, we show that this method can indeed single out water O-H groups from surface hydroxyls, and that with increasing pH, the hydrogen-bonded network of interfacial water strengthens. Furthermore, we unveil enhanced hydrogen bonding of water, compared to bulk water, at the interface with human serum albumin proteins, a prototypical bio-interface.


Assuntos
Água/química , Fluoreto de Cálcio/química , Deutério/química , Humanos , Ligação de Hidrogênio , Concentração de Íons de Hidrogênio , Albumina Sérica Humana/química , Análise Espectral/métodos , Propriedades de Superfície , Vibração
10.
J Phys Chem Lett ; 11(11): 4245-4252, 2020 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-32374610

RESUMO

The photocycle of a reversible photoisomerizing rhodopsin mimic (M2) is investigated. This system, based on the cellular retinoic acid binding protein, is structurally different from natural rhodopsin systems, but exhibits a similar isomerization upon light irradiation. More specifically, M2 displays a 15-cis to all-trans conversion of retinal protonated Schiff base (rPSB) and all-trans to 15-cis isomerization of unprotonated Schiff base (rUSB). Here we use hybrid quantum mechanics/molecular mechanics (QM/MM) tools coupled with transient absorption and cryokinetic UV-vis spectroscopies to investigate these isomerization processes. The results suggest that primary rPSB photoisomerization of M2 occurs around the C13═C14 double bond within 2 ps following an aborted-bicycle pedal (ABP) isomerization mechanism similar to natural microbial rhodopsins. The rUSB isomerization is much slower and occurs within 48 ps around the C15═N double bond. Our findings reveal the possibility to engineer naturally occurring mechanistic features into artificial rhodopsins and also constitute a step toward understanding the photoisomerization of UV pigments. We conclude by reinforcing the idea that the presence of the retinal chromophore inside a tight protein cavity is not mandatory to exhibit ABP mechanism.


Assuntos
Rodopsina/química , Rodopsina/efeitos da radiação , Isomerismo , Luz , Teoria Quântica , Receptores do Ácido Retinoico , Bases de Schiff/química , Análise Espectral/métodos
11.
Proc Natl Acad Sci U S A ; 117(23): 12836-12846, 2020 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-32457157

RESUMO

The development of methyl-transverse relaxation-optimized spectroscopy (methyl-TROSY)-based NMR methods, in concert with robust strategies for incorporation of methyl-group probes of structure and dynamics into the protein of interest, has facilitated quantitative studies of high-molecular-weight protein complexes. Here we develop a one-pot in vitro reaction for producing NMR quantities of methyl-labeled DNA at the C5 and N6 positions of cytosine (5mC) and adenine (6mA) nucleobases, respectively, enabling the study of high-molecular-weight DNA molecules using TROSY approaches originally developed for protein applications. Our biosynthetic strategy exploits the large number of naturally available methyltransferases to specifically methylate DNA at a desired number of sites that serve as probes of structure and dynamics. We illustrate the methodology with studies of the 153-base pair Widom DNA molecule that is simultaneously methyl-labeled at five sites, showing that high-quality 13C-1H spectra can be recorded on 100 µM samples in a few minutes. NMR spin relaxation studies of labeled methyl groups in both DNA and the H2B histone protein component of the 200-kDa nucleosome core particle (NCP) establish that methyl groups at 5mC and 6mA positions are, in general, more rigid than Ile, Leu, and Val methyl probes in protein side chains. Studies focusing on histone H2B of NCPs wrapped with either wild-type DNA or DNA methylated at all 26 CpG sites highlight the utility of NMR in investigating the structural dynamics of the NCP and how its histone core is affected through DNA methylation, an important regulator of transcription.


Assuntos
DNA/ultraestrutura , Ressonância Magnética Nuclear Biomolecular/métodos , Nucleossomos/ultraestrutura , Análise Espectral/métodos , Adenina/química , Isótopos de Carbono , Ilhas de CpG , Citosina/química , DNA/química , DNA/metabolismo , Metilação de DNA , Proteínas de Ligação a DNA/metabolismo , Simulação de Dinâmica Molecular , Peso Molecular
12.
An Acad Bras Cienc ; 92(1): e20181021, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32401841

RESUMO

Fosamprenavir calcium is an amprenavir prodrug of the protease inhibitors class used in the treatment of patients with acquired immunodeficiency syndrome (AIDS). Different solid forms of this drug are described in patents, in this sense studies on the physico-chemical characterization and stability are relevant for the selection of a solid form with adequate features for pharmaceutical purposes. In the present work form I (commercial) and amorphous of fosamprenavir calcium were characterized by the techniques of Differential Scanning Calorimetry (DSC), Thermogravimetry (TGA), Powder X-ray Diffraction (PXRD), Fourier-Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Furthermore, the chemical and polymorphic stability of the commercial form were evaluated by DSC, PXRD, FTIR and High-Performance Liquid Chromatography (HPLC). In the studies of characterization, thermal analyses allied to spectroscopic methods (PXRD and FTIR) demonstrated that the presence of water in the crystalline structure of Form I is fundamental for maintaining its crystallinity. In studies of accelerated stability the techniques of DSC, PXRD and FTIR showed that Form I does not suffer phase change when submitted to controlled conditions of temperature and humidity. Moreover, HPLC and FTIR proved the chemical stability of this solid form of fosamprenavir, thus demonstrating its suitability for pharmaceutical purposes.


Assuntos
Carbamatos/química , Organofosfatos/química , Preparações Farmacêuticas/análise , Sulfonamidas/química , Tecnologia Farmacêutica/métodos , Umidade , Microscopia Eletrônica de Varredura , Análise Espectral/métodos , Temperatura , Termodinâmica
13.
Food Chem ; 324: 126664, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32380410

RESUMO

Authentication of meat products is critical in the food industry. Meat adulteration may lead to religious apprehensions, financial gain and food-toxicities such as meat allergies. Thus, empirical validation of the quality and constituents of meat is paramount. Various analytical methods often based on protein or DNA measurements are utilized to identify meat species. Protein-based methods, including electrophoretic and immunological techniques, are at times unsuitable for discriminating closely related species. Most of these methods have been replaced by more accurate and sensitive detection methods, such as DNA-based techniques. Emerging technologies like DNA barcoding and mass spectrometry are still in their infancy when it comes to their utilization in meat detection. Gold nanobiosensors have shown some promise in this regard. However, its applicability in small scale industries is distant. This article comprehensively reviews the recent developments in the field of analytical methods used for porcine identification.


Assuntos
Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Produtos da Carne/análise , Suínos , Animais , Técnicas Biossensoriais , Cromatografia/métodos , DNA/análise , Análise de Alimentos/instrumentação , Espectrometria de Massas , Carne/análise , Reação em Cadeia da Polimerase , Proteínas/análise , Análise Espectral/métodos , Suínos/genética
14.
PLoS One ; 15(4): e0228923, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32236132

RESUMO

Dengue diagnostics have come a long way. Attempts at breaking away from lab-oriented dengue detection, such as NS1 antigen, IgM or IgG antibodies detection have extensively received numerous coverage. As a result, rapid detection tests (RDTs) have started to gain inroads in medical practice. Rapid detection tests notwithstanding, analysis of blood serum is still a relatively complicated task. This includes the necessity of phlebotomy, centrifugation for blood serum, and other reagent-based tests. Therefore, a non-invasive method of dengue detection was considered. In this study, we present the utility of diffuse reflectance skin spectroscopy (bandwidth of 200-2500nm) on the forearm during the triaging period for dengue screening potential. This is performed with multivariate analysis of 240 triaged febrile/suspected dengue patients. The data is then scrutinized for its clinical validity to be included as either confirmed or probable dengue, or a control group. Based on discriminant analysis of several data normalization models, we can predict the patients' clinical dengue-positivity at ranges of accuracy between ~93-98% depending on mode of the data, with a probably optimal sensitivity and specificity to the clinical diagnosis of ~89% and ~100% respectively. From the outcomes of this study, we recommend further trials with cautious optimism. With these findings, it is hoped that the elusive non-invasive detection of tropical diseases may gain platform in the near future.


Assuntos
Dengue/diagnóstico por imagem , Programas de Rastreamento/métodos , Pele/diagnóstico por imagem , Análise Espectral/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Malásia , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Sensibilidade e Especificidade , Adulto Jovem
15.
Food Chem ; 322: 126645, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32335492

RESUMO

ß-Galactosidase formulations can be added to infant milks prior to feeding to reduce the level of lactose and to avoid symptoms of lactose intolerance. The hydrolysis of lactose affects osmolality, which is an important property of infant milk. This paper introduces novel ultrasonic technology for precision, real-time, non-destructive monitoring of osmolality of infant milks, including breast milk, during enzymatic hydrolysis of lactose by supplemental ß-galactosidases. This technology can be utilised in the development and testing of ß-galactosidase formulations. Additionally, ultrasonic real-time measurements of the average degree of polymerisation and molar mass of milk saccharides throughout the hydrolysis are discussed. Comparison of the ultrasonic results with discontinuous data of osmometry and HPLC showed an excellent agreement between the different techniques. The results elucidate the osmolality dynamics involved in the enzymatic hydrolysis of lactose in milks.


Assuntos
Fórmulas Infantis/química , Lactose/química , Leite Humano/química , Análise Espectral/métodos , Ultrassom/métodos , Animais , Bovinos , Feminino , Humanos , Hidrólise , Lactente , Peso Molecular , Oligossacarídeos/química , Concentração Osmolar , beta-Galactosidase/química
17.
Biochim Biophys Acta Proteins Proteom ; 1868(6): 140413, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32179182

RESUMO

Only recently it was discovered that haemoglobin (Hb) belongs to the standard gene repertoire of insects, although their tracheal system is used for respiration. A classical oxygen-carrying function of Hb is only obvious for hexapods living in hypoxic environments. In other insect species, including the common fruit fly Drosophila melanogaster, the physiological role of Hb is yet unclear. Here, we study recombinant haemoglobin from the European honeybee Apis mellifera (Ame) and the malaria mosquito Anopheles gambiae (Aga). Spectroscopic evidence shows that both proteins can be classified as hexacoordinate Hbs with a strong affinity for the distal histidine. AgaHb1 is proposed to play a role in oxygen transport or sensing based on its multimeric state, slow autoxidation, and small but significant amount of five-coordinated haem in the deoxy ferrous form. AmeHb appears to behave more like vertebrate neuroglobin with a complex function given its diversified distribution in the genome.


Assuntos
Anopheles/metabolismo , Abelhas/metabolismo , Hemoglobinas/análise , Sistema Respiratório/metabolismo , Análise Espectral/métodos , Animais , Anopheles/genética , Abelhas/genética , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Espectroscopia de Ressonância de Spin Eletrônica/métodos , Evolução Molecular , Compostos Férricos/química , Compostos Ferrosos/química , Genoma , Heme/metabolismo , Hemoglobinas/genética , Insetos/genética , Insetos/metabolismo , Ligantes , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Modelos Moleculares , Oxigênio
18.
J Agric Food Chem ; 68(10): 3250-3259, 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32045528

RESUMO

Arabinoxylan oligosaccharides (AXOS) are a complex mixture of cereal derived, water-soluble prebiotics, obtained by enzymatic hydrolysis of arabinoxylan, a group of dietary fibers exerting numerous nutritional and health-beneficial effects. Such complex biomolecular mixtures are notoriously difficult to characterize without initial physical fractionation. Here we present the in situ analysis of AXOS using a variety of state-of-the-art sensitivity-enhanced 13C-DOSY methods, enabling virtual separation and identification of the components. Three dimensional correlation plots displaying 13C diffusivity (DOSY: Diffusion Ordered SpectroscopY), relaxation parameters (TOSY: raTe of relaxation Ordered SpectrscopY), and chemical shift offer a unique way to elucidate the composition of mixtures. We have demonstrated this multifaceted 13C probed correlation strategy in standard mixtures of aliphatic and aromatic compounds, before implementing it on AXOS. These 3D-DOSY-TOSY plots in combination with 2D-NMR correlation experiments offer unprecedented clarity for assigning chemical functions, molecular size distribution, and dynamics of oligosaccharide mixtures.


Assuntos
Espectroscopia de Ressonância Magnética/métodos , Oligossacarídeos/química , Prebióticos/análise , Análise Espectral/métodos , Hidrólise , Tamanho da Partícula , Xilanos/química
19.
Proc Natl Acad Sci U S A ; 117(9): 4942-4947, 2020 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-32071237

RESUMO

A spectroscopic paradigm has been developed that allows the magnetic field emissions generated by the electrical activity in the human body to be imaged in real time. The growing significance of imaging modalities in biology is evident by the almost exponential increase of their use in research, from the molecular to the ecological level. The method of analysis described here allows totally noninvasive imaging of muscular activity (heart, somatic musculature). Such imaging can be obtained without additional methodological steps such as the use of contrast media.


Assuntos
Técnicas e Procedimentos Diagnósticos , Músculos/diagnóstico por imagem , Músculos/metabolismo , Encéfalo/diagnóstico por imagem , Coração/diagnóstico por imagem , Humanos , Magnetocardiografia/métodos , Magnetoencefalografia/métodos , Modelos Teóricos , Mialgia/diagnóstico por imagem , Miografia/métodos , Análise Espectral/métodos
20.
PLoS One ; 15(2): e0228543, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32045426

RESUMO

Two molecules, 7-(diethylamino)coumarin-3-carbohydrazide (DCCH) and fluorescein-5-thiosemicarbazide (FTSC) were investigated in different solvents, under varying pH conditions regarding their spectroscopic properties for the usage as a Förster Resonance Energy Transfer (FRET) pair to study the molecular interaction between cellulosic surfaces. All the relevant spectroscopic properties to determine the Förster distance were measured and the performance as a FRET system was checked. From the results, it is clear that the environmental conditions need to be accurately controlled as both, but especially the FTSC dyes are sensitive to changes. For high enough concentrations positive FRET systems were observed in DMF, DMSO, H2O, THF and alkaline DMF. However due to the low quantum yield of the unmodified DCCH throughout the investigated parameter range and the strong environmental dependency of FTSC, both dyes are not preferable for being used in a FRET system for studying interaction between cellulosic surfaces.


Assuntos
Cumarínicos/química , Fluoresceínas/química , Transferência Ressonante de Energia de Fluorescência/métodos , Hidrazinas/química , Solventes/química , Análise Espectral/métodos , Transferência de Energia/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Solventes/farmacologia , Espectrometria de Fluorescência/métodos , Espectrofotometria Ultravioleta/métodos
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