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1.
Food Chem ; 333: 127514, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32683259

RESUMO

This study investigated the effect of pH on the denaturation extent, the surface chemical composition, the water sorption isotherm and the glass transition temperature of camel and bovine whey protein's powders. The LC-MS analysis indicated that the ß-Lactoglobulin was the most denatured protein in bovine whey powders regardless the pH value, while this protein was totally absent in camel whey. The α-Lactalbumin was relatively heat stable after drying and predominated the powder surface (X-ray photoelectron spectroscopy results) in both camel and bovine whey powders regardless the pH (neutral (6.7) or acidic (4.3 and 4.6)). Analysis of the water sorption isotherms indicated that decreasing the pH induced the increase of the water activity of lactose crystallization for camel and bovine whey powders. Finally, decreasing the pH led to the decrease of the glass transition temperature of camel and bovine whey powder (at 0.13, 0.23, and 0.33 of water activity).


Assuntos
Pós/química , Proteínas do Soro do Leite/química , Adsorção , Animais , Calorimetria , Camelus , Bovinos , Cromatografia Líquida de Alta Pressão , Cristalização , Concentração de Íons de Hidrogênio , Lactoglobulinas/química , Lactoglobulinas/metabolismo , Lactose/química , Espectrometria de Massas , Desnaturação Proteica , Propriedades de Superfície , Temperatura de Transição , Água/química , Proteínas do Soro do Leite/metabolismo
2.
Nucleic Acids Res ; 48(15): 8796-8807, 2020 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-32652019

RESUMO

5-Formylcytosine (5fC) is a chemically edited, naturally occurring nucleobase which appears in the context of modified DNA strands. The understanding of the impact of 5fC on dsDNA physical properties is to date limited. In this work, we applied temperature-dependent 1H Chemical Exchange Saturation Transfer (CEST) NMR experiments to non-invasively and site-specifically measure the thermodynamic and kinetic influence of formylated cytosine nucleobase on the melting process involving dsDNA. Incorporation of 5fC within symmetrically positioned CpG sites destabilizes the whole dsDNA structure-as witnessed from the ∼2°C decrease in the melting temperature and 5-10 kJ mol-1 decrease in ΔG°-and affects the kinetic rates of association and dissociation. We observed an up to ∼5-fold enhancement of the dsDNA dissociation and an up to ∼3-fold reduction in ssDNA association rate constants, over multiple temperatures and for several proton reporters. Eyring and van't Hoff analysis proved that the destabilization is not localized, instead all base-pairs are affected and the transition states resembles the single-stranded conformation. These results advance our knowledge about the role of 5fC as a semi-permanent epigenetic modification and assist in the understanding of its interactions with reader proteins.


Assuntos
Citosina/análogos & derivados , DNA/efeitos dos fármacos , Conformação Molecular/efeitos dos fármacos , Termodinâmica , Pareamento de Bases/genética , Ilhas de CpG/genética , Citosina/química , Citosina/farmacologia , DNA/química , DNA/genética , DNA de Cadeia Simples/efeitos dos fármacos , DNA de Cadeia Simples/genética , Cinética , Espectroscopia de Ressonância Magnética , Temperatura de Transição
3.
PLoS One ; 15(6): e0234502, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32525915

RESUMO

Preservation of blood plasma in the dried state would facilitate long-term storage and transport at ambient temperatures, without the need of to use liquid nitrogen tanks or freezers. The aim of this study was to investigate the feasibility of dry preservation of human plasma, using sugars as lyoprotectants, and evaluate macromolecular stability of plasma components during storage. Blood plasma from healthy donors was freeze dried using 0-10% glucose, sucrose, or trehalose, and stored at various temperatures. Differential scanning calorimetry was used to measure the glass transition temperatures of freeze-dried samples. Protein aggregation, the overall protein secondary structure, and oxidative damage were studied under different storage conditions. Differential scanning calorimetry measurements showed that plasma freeze-dried with glucose, sucrose and trehalose have glass transition temperatures of respectively 72±3.4°C, 46±11°C, 15±2.4°C. It was found that sugars diminish freeze-drying induced protein aggregation in a dose-dependent manner, and that a 10% (w/v) sugar concentration almost entirely prevents protein aggregation. Protein aggregation after rehydration coincided with relatively high contents of ß-sheet structures in the dried state. Trehalose reduced the rate of protein aggregation during storage at elevated temperatures, and plasma that is freeze- dried plasma with trehalose showed a reduced accumulation of reactive oxygen species and protein oxidation products during storage. In conclusion, freeze-drying plasma with trehalose provides an attractive alternative to traditional cryogenic preservation.


Assuntos
Proteínas Sanguíneas/metabolismo , Plasma/química , Preservação Biológica/métodos , Conservantes Farmacêuticos/química , Trealose/química , Proteínas Sanguíneas/química , Estabilidade de Medicamentos , Armazenamento de Medicamentos , Liofilização , Humanos , Agregados Proteicos , Conformação Proteica em Folha beta , Estabilidade Proteica , Temperatura de Transição , Vitrificação
4.
PLoS One ; 15(5): e0233638, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32469949

RESUMO

Pathogenic bacteria such as Salmonella enterica exhibit high desiccation tolerance, enabling long-term survival in low water activity (aw) environments. Although there are many reports on the effects of low aw on bacterial survival, the mechanism by which bacteria acquire desiccation tolerance and resistance to heat inactivation in low-aw foods remains unclear. We focused on the glass transition phenomenon, as bacteria may acquire environmental tolerance by state change due to glass transition. In this study, we determined the glass transition temperature (Tg) in S. enterica serovars under different aw conditions using thermal rheological analysis (TRA). The softening behaviour associated with the state change of bacterial cells was confirmed by TRA, and Tg was determined from the softening behaviour. Tg increased as the aw decreased in all S. enterica serovars. For example, while the Tg of five S. enterica serovars was determined as 35.16°C to 57.46°C at 0.87 aw, the Tg of all the five serovars increased by 77.10°C to 83.30°C at 0.43 aw. Furthermore, to verify the thermal tolerance of bacterial cells, a thermal inactivation assay was conducted at 60°C for 10 min under each aw condition. A higher survival ratio was observed as aw decreased; this represented an increase in Tg for Salmonella strains. These results suggest that the glass transition phenomenon of bacterial cells would associate with environmental tolerance.


Assuntos
Salmonella enterica/fisiologia , Dessecação , Microbiologia de Alimentos , Temperatura Alta , Termotolerância , Temperatura de Transição , Vitrificação , Água/análise
5.
Food Chem ; 322: 126764, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32325364

RESUMO

Plasmalogens are dietary phospholipids with beneficial health effects. In this work, plasmalogen characteristics and changes in beef during boiling, frying, and roasting were comprehensively investigated by liquid-chromatography-mass spectrometry. The alteration of plasmalogen fingerprint during cooking processes was found by untargeted omics approach, in which time of boiling, temperature of roasting, and meat core/surface of frying were responsible for the observed variations. Moreover, the targeted determination of representative plasmalogen species showed significant loss with a temperature- and time-dependent manner in roasting and frying. And frying even showed an extra loss in meat surface compared with core. Furthermore, an artificial neural network-based predictive model elucidated the dynamics of plasmalogen species during cooking. Finally, batter-coating pretreatment was performed to show its protection against plasmalogens loss during frying. These results might provide a potential strategy to better control and improve the quality of functional foodstuffs during cooking processes.


Assuntos
Culinária/métodos , Plasmalogênios/análise , Plasmalogênios/química , Carne Vermelha , Animais , Bovinos , Cromatografia Líquida de Alta Pressão , Análise de Alimentos/métodos , Análise de Alimentos/estatística & dados numéricos , Temperatura Alta , Redes Neurais de Computação , Carne Vermelha/análise , Espectrometria de Massas em Tandem , Temperatura de Transição
6.
Nat Methods ; 17(5): 495-503, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32284610

RESUMO

We have used a mass spectrometry-based proteomic approach to compile an atlas of the thermal stability of 48,000 proteins across 13 species ranging from archaea to humans and covering melting temperatures of 30-90 °C. Protein sequence, composition and size affect thermal stability in prokaryotes and eukaryotic proteins show a nonlinear relationship between the degree of disordered protein structure and thermal stability. The data indicate that evolutionary conservation of protein complexes is reflected by similar thermal stability of their proteins, and we show examples in which genomic alterations can affect thermal stability. Proteins of the respiratory chain were found to be very stable in many organisms, and human mitochondria showed close to normal respiration at 46 °C. We also noted cell-type-specific effects that can affect protein stability or the efficacy of drugs. This meltome atlas broadly defines the proteome amenable to thermal profiling in biology and drug discovery and can be explored online at http://meltomeatlas.proteomics.wzw.tum.de:5003/ and http://www.proteomicsdb.org.


Assuntos
Regulação da Expressão Gênica , Células Procarióticas/metabolismo , Proteínas/química , Proteínas/metabolismo , Proteoma/análise , Temperatura de Transição , Animais , Complexo de Proteínas da Cadeia de Transporte de Elétrons/metabolismo , Humanos , Mitocôndrias/metabolismo , Estabilidade Proteica , Software , Especificidade da Espécie
7.
Arch Biochem Biophys ; 686: 108368, 2020 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-32315654

RESUMO

Phospholipid bilayer constitutes the basis of the cell membrane. Any changes in its structure and dynamics could significantly affect the properties and functions of the cell membrane and associated proteins. It could, in its turn, affect the mechanism and strength of drug-membrane interaction. Phase transitions in lipid bilayer play an important role in cell life and in transmembrane transport of ions and drug molecules. In the present study we have tried to clarify the mechanism of glycyrrhizin bioactivity by the study of its influence on the lipid dynamics and phase transition of the lipid bilayer. For this purpose, a combination of nuclear magnetic resonance (NMR) and molecular dynamic (MD) simulations was used. Glycyrrhizin is the saponin extracted from licorice root. It displays a wide spectrum of biological activity and is frequently used in traditional medicine since ancient times. Now glycyrrhizin attracts additional attention as a novel multifunctional drug delivery system. We have established that glycyrrhizin interaction with dipalmitoylphosphatidylcholine lipid bilayers leads to changes in lipid mobility and phase transition temperature. NMR and MD results demonstrated that a glycyrrhizin molecule is able to integrate into a lipid bilayer and form stable aggregates inside. We hypothesize that surface curvatures caused by local changes in the lipid composition and the presence of phase boundaries might affect the permeability of the cell membrane.


Assuntos
1,2-Dipalmitoilfosfatidilcolina/química , Ácido Glicirrízico/química , 1,2-Dipalmitoilfosfatidilcolina/análogos & derivados , Membrana Celular/química , Permeabilidade da Membrana Celular , Cinética , Bicamadas Lipídicas/química , Simulação de Dinâmica Molecular , Transição de Fase , Espectroscopia de Prótons por Ressonância Magnética , Termodinâmica , Temperatura de Transição
8.
PLoS One ; 15(3): e0230443, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32191752

RESUMO

Polyhydroxybutyrate (PHB) is a biodegradable biopolymer which is useful for various applications including packing, medical and coating materials. An endospore-forming bacterium (strain BP17) was isolated from composted soil and evaluated for PHB production. Strain BP17, taxonomically identified as Bacillus drentensis, showed enhanced PHB accumulation and was selected for further studies. To achieve maximum PHB production, the culture conditions for B. drentensis BP17 were optimized through response surface methodology (RSM) employing central composite rotatable design (CCRD). The final optimum fermentation conditions included: pineapple peel solution, 11.5% (v/v); tryptic soy broth (TSB), 60 g/L; pH, 6.0; inoculum size, 10% (v/v) and temperature, 28°C for 36 h. This optimization yielded 5.55 g/L of PHB compared to the non-optimized condition (0.17 g/L). PHB accumulated by B. drentensis BP17 had a polydispersity value of 1.59 and an average molecular weight of 1.15x105 Da. Thermal analyses revealed that PHB existed as a thermally stable semi-crystalline polymer, exhibiting a thermal degradation temperature of 228°C, a melting temperature of 172°C and an apparent melting enthalpy of fusion of 83.69 J/g. It is evident that B. drentensis strain BP17 is a promising bacterium candidate for PHB production using agricultural waste, such as pineapple peel as a low-cost alternative carbon source for PHB production.


Assuntos
Ananas/química , Bacillus/metabolismo , Hidroxibutiratos/metabolismo , Plásticos/metabolismo , Resíduos , Análise de Variância , Bacillus/citologia , Bacillus/ultraestrutura , Filogenia , Espectroscopia de Prótons por Ressonância Magnética , RNA Ribossômico 16S/genética , Fatores de Tempo , Temperatura de Transição
9.
PLoS One ; 15(3): e0230028, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32155196

RESUMO

The heterogeneous melting kinetics of polycrystalline aluminum is investigated by a theoretical model which represents the overall melting rate as a functional of the Weibull grain-size-distribution. It is found that the melting process is strongly affected by the mean-grain-diameter, but is insensitive to the shape parameter of the Weibull distribution. The temperature-time-transformation (TTT) diagrams are calculated to probe dependence of the characteristic timescale of melting on the overheating temperature and the mean-grain-diameter. The model predicts that the heterogeneous melting time of polycrystalline aluminum exponentially depends on temperature in high temperature range and the exponent constant is an intrinsic material constant independent of the mean-grain-diameter. Comparisons between TTT diagrams of heterogeneous melting and homogenous melting are also provided.


Assuntos
Alumínio/química , Transição de Fase , Cinética , Modelos Moleculares , Temperatura de Transição
10.
Artigo em Inglês | MEDLINE | ID: mdl-32145639

RESUMO

Destruction of assembly structures has been identified as a major cause for activity loss of virus and virus-like particles during their chromatographic process. A deep insight into the denaturation process at the solid-liquid interfaces is important for rational design of purification. In this study, in-situ differential scanning calorimetry (DSC) was employed to study the dissociation process of inactivated foot-and-mouth disease virus (FMDV) during ion exchange chromatography (IEC) at different levels of pH. The intact FMDV known as 146S and the dissociation products were quantified by high performance size exclusion chromatography (HPSEC) and the thermo-stability of 146S on-column was monitored in-situ by DSC. Serious dissociation was found at pH 7.0 and pH 8.0, leading to low 146S recoveries of 12.3% and 43.7%, respectively. The elution profiles from IEC and HPSEC combined with the thermal transition temperatures of 146S dissociation (Tm1) from DSC suggested two denaturation mechanisms that the 146S dissociation occurred on-column after adsorption at pH 7.0 and during elution step at pH 8.0. By appending different excipients including sucrose, the improvement of 146S recovery and reduced dissociation was found highly correlated to increment of 146S stability on-column detected by DSC. The highest recovery of 99.9% and the highest Tm1 of 54.49 °C were obtained at pH 9.0 with 20% (w/v) sucrose. According to chromatographic behaviors and Tm1, three different dissociation processes in IEC were discussed. The study provides a perspective to understand the denaturation process of assemblies during chromatography, and also supplies a strategy to improve assembly recovery.


Assuntos
Vírus da Febre Aftosa/química , Substâncias Macromoleculares/química , Adsorção , Cromatografia em Gel , Cromatografia por Troca Iônica , Humanos , Concentração de Íons de Hidrogênio , Transição de Fase , Propriedades de Superfície , Temperatura de Transição
11.
Food Chem ; 315: 126208, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32032831

RESUMO

The aim of the current work was to evaluate the physicochemical, rheological, molecular, thermal and sensory properties of complementary food (CF) formulations prepared with quinoa (Chenopodium quinoa Willd.) flour (QF). It was observed that QF addition significantly affected the physicochemical and rheological properties of CF formulations, resulting in higher protein and crude fiber, but lower total sugar contents and increased storage (G') and loss (G″) modulus values. The glass transition temperature decreased due to QF addition. The FTIR spectra revealed the presence of aromatic amino acids derived from QF. GC, GC-MS and GC-O analyses revealed the presence of 50 aroma and 23 aroma-active compounds, among which aldehydes, alcohols and ketones were the most prevalent group of compounds. The formulation with 8% QF received the highest sensory scores. QF could be used to improve the physicochemical, rheological, thermal and sensory properties of CF products.


Assuntos
Chenopodium quinoa/química , Alimentos Infantis , Odorantes/análise , Paladar , Adulto , Dieta Livre de Glúten , Farinha/análise , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Lactente , Alimentos Infantis/análise , Mães , Reologia , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura de Transição , Compostos Orgânicos Voláteis/análise
12.
Phys Chem Chem Phys ; 22(9): 5301-5313, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32096507

RESUMO

Biomedical industries are widely exploring the use of thermo-responsive polymers (TRPs) in the advanced development of drug delivery and in many other pharmaceutical applications. There is a great need to investigate the use of less toxic and more (bio-)compatible TRPs employing several additives, which could modify the conformational transition behavior of TRPs in aqueous solution. To move forward in this aspect, we have chosen the less toxic bio-based polymer poly(N-vinylcaprolactam) (PVCL) and three different methylamine-based osmolytes, trimethylamine N-oxide (TMAO), betaine and sarcosine, in order to investigate their particular interactions with the polymer segments in PVCL and therefore the corresponding changes in the thermo-responsive conformational behavior. Several biophysical techniques, UV-visible spectroscopy, fluorescence spectroscopy, dynamic light scattering (DLS) and laser Raman spectroscopy, as well as classical computer simulation methods such as molecular dynamics are employed in the current work. All the studied methylamines are found to favor the hydrophobic collapse of the polymer thus stabilizing the globular state of PVCL. Sarcosine is observed to cause the maximum decrease in lower critical solution temperature (LCST) of PVCL followed by TMAO and then betaine. The differences observed in the LCST values of PVCL in the presence of these molecules can be attributed to the different polymer-osmolyte interactions. The less sterically hindered N atom in the case of sarcosine causes a significant difference in the phase transition temperature values of PVCL compared to betaine and TMAO, where the nitrogen atom is buried by three methyl groups attached to it.


Assuntos
Caprolactama/análogos & derivados , Metilaminas/química , Simulação de Dinâmica Molecular , Polímeros/química , Betaína/química , Caprolactama/química , Interações Hidrofóbicas e Hidrofílicas , Conformação Molecular , Transição de Fase , Sarcosina/química , Temperatura de Transição , Água/química
13.
Int J Mol Sci ; 21(1)2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31906437

RESUMO

Nanobodies (Nbs) are the smallest antigen-binding, single domain fragments derived from heavy-chain-only antibodies from Camelidae. Among the several advantages over conventional monoclonal antibodies, their small size (12-15 kDa) allows them to extravasate rapidly, to show improved tissue penetration, and to clear rapidly from blood, which are important characteristics for cancer imaging and targeted radiotherapy. Herein, we identified Nbs against CD33, a marker for acute myeloid leukemia (AML). A total of 12 Nbs were generated against recombinant CD33 protein, out of which six bound natively CD33 protein, expressed on the surface of acute myeloid leukemia THP-1 cells. The equilibrium dissociation constants (KD) of these six Nbs and CD33 range from 4 to 270 nM, and their melting temperature (Tm) varies between 52.67 and 67.80 °C. None of these Nbs showed leukemogenicity activity in vitro. The selected six candidates were radiolabeled with 99mTc, and their biodistribution was evaluated in THP-1-tumor-bearing mice. The imaging results demonstrated the fast tumor-targeting capacity of the Nbs in vivo. Among the anti-CD33 Nbs, Nb_7 showed the highest tumor uptake (2.53 ± 0.69 % injected activity per gram (IA/g), with low background signal, except in the kidneys and bladder. Overall, Nb_7 exhibits the best characteristics to be used as an anti-CD33 targeting vehicle for future diagnostic or therapeutic applications.


Assuntos
Leucemia Mieloide Aguda/imunologia , Lectina 3 Semelhante a Ig de Ligação ao Ácido Siálico/imunologia , Anticorpos de Domínio Único/metabolismo , Animais , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Epitopos/imunologia , Feminino , Humanos , Cinética , Camundongos , Camundongos SCID , Lectina 3 Semelhante a Ig de Ligação ao Ácido Siálico/genética , Anticorpos de Domínio Único/genética , Distribuição Tecidual , Tomografia Computadorizada de Emissão de Fóton Único , Temperatura de Transição
14.
Chemistry ; 26(10): 2164-2168, 2020 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-31913530

RESUMO

A C-nucleoside with 6-phenyl-1H-carbazole as the base moiety has been synthesized and incorporated in the middle of an oligonucleotide. Mercuration of this modified residue at positions 1 and 8 gave the first example of an oligonucleotide featuring a monofacial dinuclear organometallic nucleobase. The dimercurated oligonucleotide formed stable duplexes with unmodified oligonucleotides placing either cytosine, guanine, or thymine opposite to the organometallic nucleobase. A highly stabilizing (ΔTm =7.3 °C) HgII -mediated base pair was formed with thymine. According to DFT calculations performed at the PBE0DH level of theory, this base pair is most likely dinuclear, with the two HgII ions coordinated to O2 and O4 of the thymine base.


Assuntos
Carbazóis/química , Compostos Organomercúricos/química , Timina/química , Pareamento de Bases , Sequência de Bases , Carbazóis/metabolismo , Teoria da Densidade Funcional , Conformação Molecular , Oligonucleotídeos/síntese química , Oligonucleotídeos/química , Timina/metabolismo , Temperatura de Transição
15.
Molecules ; 25(2)2020 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-31963165

RESUMO

New four isomeric chair architectures of 1:1 H-bonded supramolecular complexes were prepared through intermolecular interactions between 4-(2-(pyridin-4-yl)diazenyl-(2-(or 3-)chlorophenyl) 4-alkoxybenzoates and 4-n-alkoxybenzoic acids. The H-bond formation of all complexes was confirmed by differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). Mesomorphic characterization was carried by DSC and polarized optical microscopy (POM). It was found that all prepared laterally chloro-substituted supramolecular complexes were nematogenic, and exhibited nematic phase and low melting temperature. The thermal stability of the nematic mesophase observed depends upon the location and spatial orientation of the lateral Cl- atom in as well as the length of terminal chains. Theoretical calculations were carried out within the paradigm of the density functional theory (DFT) in order to establish the molecular conformation for the formed complexes and estimate their thermal parameters. The results of the computational calculations revealed that the H-bonded complexes were in a chair form molecular geometry. Additionally, out of the acquired data, it was possible to designate the influence of the position and orientation of the lateral group as well as the alkoxy chain length on the stability of the nematic phase.


Assuntos
Ligação de Hidrogênio , Cristais Líquidos/química , Modelos Teóricos , Teoria da Densidade Funcional , Conformação Molecular , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura de Transição
16.
Int J Biol Macromol ; 148: 956-968, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31972200

RESUMO

Starch extracted from lily bulb (Lilium brownii var. Viridulum Baker) was modified via heat-moisture treatment (HMT) at different moisture levels (15-35%) and acid treatment (AT) with hydrochloric acid at five different concentrations (0.25-2.0 M). The effects of HMT and AT on the physicochemical properties and in vitro digestibility of lily starch were investigated. HMT and AT led to the clustering of the starch granules, whose surface became rougher, thereby increasing the particle size. X-ray diffraction results showed that HMT increased the relative crystallinity and transformed the crystalline structure from B- to A-type. The relative crystallinity and X-ray patterns of the AT starch significantly increased. The swelling power of HMT and AT starch was significantly reduced, whereas the solubility of HMT starch decreased. The solubility of AT starch was significantly higher than that of native starch (NS) (p < 0.05). Differential scanning calorimetry revealed that the gelatinization temperature of lily starch was higher than that of NS after two modifications, whereas the gelatinization enthalpy of the NS was lower than that of the modified samples. The starch with HMT at 25% showed the highest resistant starch content of 44.15% in cooked samples.


Assuntos
Lilium/química , Extratos Vegetais/química , Amido/química , Cristalização , Digestão , Temperatura Alta , Ácido Clorídrico/química , Hidrogéis/química , Estrutura Molecular , Tamanho da Partícula , Transição de Fase , Solubilidade , Propriedades de Superfície , Termodinâmica , Temperatura de Transição , Água
17.
Int J Biol Macromol ; 148: 851-856, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31982522

RESUMO

Bast flax fibers were treated, with or without ultrasound assistance, using a low melting mixture (LMM) composed of lactic acid, d-glucose and water. This LMM treatment affected both lignin and hemicelluloses contents and modified the fibers properties identified as crucial parameters in an industrial context, i.e. coloration, wettability, crystallinity, fibers diameter and chemical composition. Surface chemistry of the fibers were investigated through fluorescent tagged carbohydrates binding modules revealing macromolecular rearrangements responsible of both a fibers crystallinity enhancement and an unexpected hydrophobicity. It has been found that LMM treatments bleach fibers, which is considered a beneficial effect independent of the treatments.


Assuntos
Linho/química , Lignina/química , Carboidratos/química , Cristalização , Corantes Fluorescentes/química , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Imagem Óptica , Polissacarídeos/química , Ligação Proteica , Propriedades de Superfície , Temperatura de Transição
18.
J Forensic Sci ; 65(1): 52-60, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31433500

RESUMO

Mitragyna speciosa (MS), a plant commonly known as kratom, is a widely used "legal high" opiate alternative for pain relief. DNA extracted from MS and 26 additional plant species was amplified by PCR using primers targeting the strictosidine beta-D-glucosidase (SGD) and secologanin synthase 2 (SLS2) genes and detected by high-resolution melt curves using three intercalating dyes. Amplicon sizes were confirmed using agarose gel electrophoresis. The observed melt temperatures for SGD and SLS2 were 77.08 ± 0.38°C and 77.61 ± 0.46°C, respectively, using SYBR® Green I; 80.18 ± 0.27°C and 80.59 ± 0.08°C, respectively, using Radiant™ Green; and 82.19 ± 0.04°C and 82.62 ± 0.13°C, respectively, using the LCGreen® PLUS dye. The SLS2 primers demonstrated higher specificity and identified MS DNA at 0.05 ng/µL. In a duplex reaction, SLS2 and tetrahydrocannabinoic acid synthase gene primers detected and differentiated MS and Cannabis sativa (CS) by melt peaks at 82.63 ± 0.35°C and 85.58 ± 0.23°C, respectively, using LCGreen® PLUS.


Assuntos
Cannabis/genética , DNA de Plantas/genética , Toxicologia Forense/métodos , Mitragyna/genética , Primers do DNA , Eletroforese em Gel de Ágar , Humanos , Reação em Cadeia da Polimerase em Tempo Real , Temperatura de Transição
19.
Biophys Chem ; 256: 106270, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31706136

RESUMO

DNA strands can be designed to assemble into stable three-dimensional structures, based on Watson-Crick base pairing rules. The simplest of these is the DNA tetrahedron that is composed of four oligonucleotides. We have re-designed the sequence of a DNA tetrahedron so that it contains a single (AATT) binding site for the minor groove binding ligand Hoechst 33258. We examined the stability of this structure by placing fluorescent groups within each of its edges and have shown that all the edges melt at the same temperature in the absence of the ligand. The minor groove ligand still binds to its recognition sequence within the tetrahedron and increases the melting temperature of the folded complex. This ligand-induced stabilisation is propagated into the adjacent helical arms and the tetrahedron melts as a single entity in a cooperative fashion.


Assuntos
DNA/química , Ligantes , Sequência de Bases , Sítios de Ligação , Bisbenzimidazol/química , Bisbenzimidazol/metabolismo , Conformação de Ácido Nucleico , Transição de Fase/efeitos da radiação , Espectrometria de Fluorescência , Temperatura de Transição , Raios Ultravioleta
20.
Chemosphere ; 239: 124496, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31505446

RESUMO

Electrical resistance heating (ERH) is a promising thermal remediation method for treating volatile soil pollutants. However, the remediation of soil contaminated by polycyclic aromatic hydrocarbons (PAHs) based on lab-scale ERH devices must be extensively studied to determine the factors affecting the remediation. Therefore, this study used a lab-scale ERH equipment to investigate the influence factors of ERH, PAH removal efficiency, and changes in soil properties through the treatment process. The results suggested that moisture and salinity were basic factors affecting electric conductive capability; heating 15 g of soil to the target temperature required at least 4 g solution of 0.1% salt. Meanwhile, higher electric strength can ensure heating efficiency and maximum temperature. The removal efficiency of PAHs, which is highly related to boiling point, was significantly affected by its benzene rings and bond structure; during 90 min ERH treatment, more than 40% of the pollutants were removed synchronously with the evaporation of water. Hence, co-boiling with water was confirmed to be the primary mechanism of ERH. The influence of the treatment on soil properties (organic matter, particle size, fertility, enzymatic activity) was limited, suggesting that soil functionality can be retained by ERH.


Assuntos
Poluição Ambiental/análise , Recuperação e Remediação Ambiental/métodos , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes do Solo/análise , Solo/química , Impedância Elétrica , Calefação , Temperatura Alta , Temperatura de Transição
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