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1.
J Chem Theory Comput ; 16(1): 782-793, 2020 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-31751511

RESUMO

We present a coarse-grained (CG) force field (FF), pSPICA, for lipid membranes that incorporates a CG polar water model, which guarantees a reasonable dielectric response for water. Using a relatively simple functional form for the interaction, the CG parameters were systematically optimized to reproduce surface/interfacial tension, density, solvation or transfer free energy, as well as distribution functions obtained from all-atom molecular dynamics trajectory generated with the CHARMM FF, following the scheme used in the SPICA FF. Lipid membranes simulated using the present CG FF demonstrate reasonable membrane area and thickness, elasticity, and line tension, which ensure that the simulated lipid membranes exhibit proper mesoscopic morphology. The major advantages of the pSPICA FF with a polar water model were its ability to simulate membrane electroporation and its superior performance in the morphological characterization of charged lipid aggregates. We also demonstrated that the pSPICA can better describe the membrane permeation of hydrophilic segments involving a water string formation.


Assuntos
Lipídeos de Membrana/química , Água/química , Alcanos/química , Eletroporação , Bicamadas Lipídicas/química , Simulação de Dinâmica Molecular , Termodinâmica
2.
Chemosphere ; 239: 124796, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31520972

RESUMO

In July 2013, a fatal train derailment led to an explosion and fire in the town of Lac-Mégantic (LM), Quebec, and the crude oil contamination of regional surface water, soil, and sediment in the adjacent Lake Mégantic. This study investigated the degradation potential of the spilled crude oil by using the sediments from the incident site as the source of microorganisms. Two light crude oils (LM source oil and Alberta Sweet Mixed Blend (ASMB)) were tested at 22 °C for 4 weeks and 4 °C for 8 weeks, respectively. The post-incubation biological and chemical information of the samples were analysed. There was no marked difference in degradation efficacy and biological activities for both the LM and ASMB oils, although the biodegradation potential differed between the two incubations. Higher temperature favoured the growth of microorganisms, thus for the degradation of all petroleum hydrocarbons, except for some conservative biomarkers. The degradation of both oils followed the order of resolved components > total saturated hydrocarbons (TSH) > unresolved complex mixture (UCM) >total aromatic hydrocarbons (TAH). Normal alkanes were generally degraded more significantly than branched ones, and polycyclic aromatic hydrocarbons (PAHs). Degradation of polycyclic aromatic hydrocarbons (PAHs) and their alkylated congeners (APAHs) for both incubations generally decreased as the number of aromatic rings, and the degree of alkylation increased. This study showed that the LM sediments can biodegrade the petroleum hydrocarbons efficaciously if appropriate ambient temperatures are generated to favour the growth of autochthonous microorganisms.


Assuntos
Sedimentos Geológicos/microbiologia , Hidrocarbonetos/química , Hidrocarbonetos/metabolismo , Petróleo/metabolismo , Poluentes Químicos da Água/metabolismo , Alcanos/química , Alcanos/metabolismo , Biodegradação Ambiental , Lagos/microbiologia , Poluição por Petróleo , Hidrocarbonetos Policíclicos Aromáticos/química , Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Quebeque , Temperatura Ambiente , Poluentes Químicos da Água/química
3.
Food Chem ; 305: 125486, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31520920

RESUMO

The formation of 3-methyl-2,4-nonanedione (MND) during red wine aging can contribute to the premature evolution of aroma, characterized by the loss of fresh fruit and development of dried fruit flavors. The identification of two new hydroxy ketones, 2-hydroxy-3-methylnonan-4-one (syn- and anti-ketol diastereoisomers) and 3-hydroxy-3-methyl-2,4-nonanedione (HMND), prompted the investigation of the precursors and pathways through which MND is produced and evolves. An HS-SPME-GC-MS method was optimized for their quantitation in numerous must and wine samples, providing insight into the evolution of MND, HMND, and ketols through alcoholic fermentation and wine aging. Alcoholic fermentation resulted in a significant decrease in MND and HMND and the simultaneous appearance of ketol diastereoisomers. The analysis of 167 dry red wines revealed significant increases in MND and anti-ketol contents through aging and a significant positive correlation between MND and anti-ketols. Additional experiments demonstrated that ketols are precursors to MND during red wine oxidation.


Assuntos
Alcanos/química , Diacetil/análogos & derivados , Sucos de Frutas e Vegetais/análise , Cetonas/análise , Vinho/análise , Alcanos/metabolismo , Diacetil/química , Diacetil/metabolismo , Etanol/química , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Concentração de Íons de Hidrogênio , Cetonas/isolamento & purificação , Limite de Detecção , Microextração em Fase Sólida , Estereoisomerismo , Fatores de Tempo
4.
J Chem Ecol ; 45(10): 823-837, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31701385

RESUMO

European badgers, Meles meles, are group-living in the UK, and demarcate their ranges with shared latrines. As carnivores, badgers possess paired anal glands, but olfactory information on the content of badger anal gland secretion (AGS) is largely uninvestigated. Here, we examined the volatile organic compounds (VOCs) of AGS samples from 57 free-living badgers using solid-phase microextraction (SPME) and gas chromatography-mass spectrometry. AGS was rich in alkanes (C7-C15, 14.3% of identified compounds), aldehydes (C5-C14, 9.7%), phenols (C6-C15, 9.5%), alcohols (C5-C10, 7.3%), aromatic hydrocarbons (C6-C13, 6.8%), ketones (C6-C13, 6.3%) and carboxylic acids (C3-C12, 5.6%) and contained a variety of esters, sulfurous and nitrogenous compounds, and ethers. The number of VOCs per profile ranged from 20 to 111 (mean = 65.4; ± 22.7 SD), but no compound was unique for any of the biological categories. After normalization of the raw data using Probabilistic Quotient Normalization, we produced a resemblance matrix by calculating the Euclidian distances between all sample pairs. PERMANOVA revealed that AGS composition differs between social groups, and concentration and complexity in terms of number of measurable VOCs varies between seasons and years. AGS VOC profiles encode individual identity, sex and vary with female reproductive state, indicating an important function in intraspecific communication. Because AGS is excreted together with fecal deposits, we conclude that chemical complexity of AGS enables particularly latrine-using species, such as badgers, to advertise more complex individual-specific information than in feces alone.


Assuntos
Canal Anal/química , Mustelidae/fisiologia , Feromônios/química , Alcanos/química , Alcanos/isolamento & purificação , Alcanos/farmacologia , Canal Anal/metabolismo , Comunicação Animal , Animais , Comportamento Animal/efeitos dos fármacos , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Feromônios/isolamento & purificação , Feromônios/farmacologia , Estações do Ano , Microextração em Fase Sólida , Compostos Orgânicos Voláteis/química , Compostos Orgânicos Voláteis/isolamento & purificação , Compostos Orgânicos Voláteis/farmacologia
5.
Nature ; 574(7777): 246-248, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31554964

RESUMO

The study of childhood diet, including breastfeeding and weaning, has important implications for our understanding of infant mortality and fertility in past societies1. Stable isotope analyses of nitrogen from bone collagen and dentine samples of infants have provided information on the timing of weaning2; however, little is known about which foods were consumed by infants in prehistory. The earliest known clay vessels that were possibly used for feeding infants appear in Neolithic Europe, and become more common throughout the Bronze and Iron Ages. However, these vessels-which include a spout through which liquid could be poured-have also been suggested to be feeding vessels for the sick or infirm3,4. Here we report evidence for the foods that were contained in such vessels, based on analyses of the lipid 'fingerprints' and the compound-specific δ13C and Δ13C values of the major fatty acids of residues from three small, spouted vessels that were found in Bronze and Iron Age graves of infants in Bavaria. The results suggest that the vessels were used to feed infants with milk products derived from ruminants. This evidence of the foodstuffs that were used to either feed or wean prehistoric infants confirms the importance of milk from domesticated animals for these early communities, and provides information on the infant-feeding behaviours that were practised by prehistoric human groups.


Assuntos
Alimentação Artificial/história , Sepultamento , Cerâmica , Leite/química , Ruminantes , Alcanos/análise , Alcanos/química , Animais , Sepultamento/história , Cemitérios , Cerâmica/história , Criança , Gorduras na Dieta/análise , Alemanha , História Antiga , Humanos , Leite/história
6.
Chemistry ; 25(66): 15062-15066, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31553484

RESUMO

The aldol reaction is one of the most fundamental stereocontrolled carbon-carbon bond-forming reactions and is mainly catalyzed by aldolases in nature. Despite the fact that the aldol reaction has been widely proposed to be involved in fungal secondary metabolite biosynthesis, a dedicated aldolase that catalyzes stereoselective aldol reactions has only rarely been reported in fungi. Herein, we activated a cryptic polyketide biosynthetic gene cluster that was upregulated in the fungal wheat pathogen Parastagonospora nodorum during plant infection; this resulted in the production of the phytotoxic stemphyloxin II (1). Through heterologous reconstruction of the biosynthetic pathway and in vitro assay by using cell-free lysate from Aspergillus nidulans, we demonstrated that a berberine bridge enzyme (BBE)-like protein SthB catalyzes an intramolecular aldol reaction to establish the bridged tricyclo[6.2.2.02,7 ]dodecane skeleton in the post-assembly tailoring step. The characterization of SthB as an aldolase enriches the catalytic toolbox of classic reactions and the functional diversities of the BBE superfamily of enzymes.


Assuntos
Alcanos/química , Berberina/química , Frutose-Bifosfato Aldolase/metabolismo , Perileno/metabolismo , Ascomicetos/genética , Ascomicetos/metabolismo , Aspergillus nidulans/metabolismo , Biocatálise , Frutose-Bifosfato Aldolase/química , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Conformação Molecular , Família Multigênica , Perileno/análogos & derivados , Perileno/química , Estereoisomerismo
7.
Analyst ; 144(20): 5971-5979, 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31498361

RESUMO

Alkaline phosphatase (ALP) is an important enzyme related to many clinical diseases and also widely used as a labeling enzyme for immunoassay. Herein, a new electrochemical sensing strategy for ALP activity was proposed, which was based on the ALP-triggered methylene blue (MB) release from a lanthanide coordination polymer and successive penetration through a self-assembled dodecanethiol monolayer for electrochemical response. The supramolecular lanthanide coordination polymer was constructed by using guanine monophosphate (GMP) and Tb3+ as the ligand and the metal ion, respectively, and the encapsulated MB as the signal molecule. ALP catalyzed the cleavage of the phosphate group from the GMP ligand and disrupted the coordination polymer network to release abundant MB molecules for electrochemical responses related to ALP activity. The obtained lanthanide coordination polymers were well characterized by various techniques. The fabricated electrochemical sensor for ALP activity assay shows distinct advantages such as being one-step, label-free, immobilization-free and highly sensitive. The detection limit toward ALP activity was down to 0.5 U L-1. With the aid of a MB enrichment process on the modified electrode before measurement, the detection limit could be further improved to 0.1 U L-1. Moreover, the assay method could be applied for ALP detection in complex matrixes such as human serum and also for efficient inhibitor evaluation. Thus, the current study provides a new pathway to the fabrication of a coordination polymer-based electrochemical sensing platform for applications in disease diagnosis and drug discovery.


Assuntos
Fosfatase Alcalina/análise , Bioensaio , Azul de Metileno/química , Polímeros/química , Térbio/química , Alcanos/química , Bioensaio/métodos , Catálise , Técnicas Eletroquímicas/métodos , Sensibilidade e Especificidade
8.
Biomed Res Int ; 2019: 6593125, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31467905

RESUMO

Methanolic extract of Clinacanthus nutans Lindau leaves (MECN) has been reported to exert antinociceptive activity. The present study aimed to elucidate the possible antinociceptive mechanisms of a lipid-soluble fraction of MECN, which was obtained after sequential extraction in petroleum ether. The petroleum ether fraction of C. nutans (PECN), administered orally to mice, was (i) subjected to capsaicin-, glutamate-, phorbol 12-myristate 13-acetate-, bradykinin-induced nociception model; (ii) prechallenged (intraperitoneal (i.p.)) with 0.15 mg/kg yohimbine, 1 mg/kg pindolol, 3 mg/kg caffeine, 0.2 mg/kg haloperidol, or 10 mg/kg atropine, which were the respective antagonist of α 2-adrenergic, ß-adrenergic, adenosinergic, dopaminergic, or muscarinic receptors; and (iii) prechallenged (i.p.) with 10 mg/kg glibenclamide, 0.04 mg/kg apamin, 0.02 mg/kg charybdotoxin, or 4 mg/kg tetraethylammonium chloride, which were the respective inhibitor of ATP sensitive-, small conductance Ca2+-activated-, large conductance Ca2+-activated-, or nonselective voltage-activated-K+ channel. Results obtained demonstrated that PECN (100, 250, and 500 mg/kg) significantly (P<0.05) inhibited all models of nociception described earlier. The antinociceptive activity of 500 mg/kg PECN was significantly (P<0.05) attenuated when prechallenged with all antagonists or K+ channel blockers. However, only pretreatment with apamin and charybdotoxin caused full inhibition of PECN-induced antinociception. The rest of the K+ channel blockers and all antagonists caused only partial inhibition of PECN antinociception, respectively. Analyses on PECN's phytoconstituents revealed the presence of antinociceptive-bearing bioactive compounds of volatile (i.e., derivatives of γ-tocopherol, α-tocopherol, and lupeol) and nonvolatile (i.e., cinnamic acid) nature. In conclusion, PECN exerts a non-opioid-mediated antinociceptive activity involving mainly activation of adenosinergic and cholinergic receptors or small- and large-conductance Ca2+-activated-K+ channels.


Assuntos
Acanthaceae/química , Analgésicos/farmacologia , Dor Nociceptiva/tratamento farmacológico , Extratos Vegetais/farmacologia , Alcanos/química , Analgésicos/química , Analgésicos não Entorpecentes/química , Analgésicos não Entorpecentes/farmacologia , Animais , Bradicinina/toxicidade , Capsaicina/toxicidade , Ácido Glutâmico/toxicidade , Humanos , Metanol/química , Camundongos , Dor Nociceptiva/induzido quimicamente , Dor Nociceptiva/patologia , Extratos Vegetais/química , Folhas de Planta/química , Canais de Potássio/genética , Acetato de Tetradecanoilforbol/análogos & derivados , Acetato de Tetradecanoilforbol/toxicidade
9.
J Basic Microbiol ; 59(8): 792-806, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31368594

RESUMO

The aim of this study was to examine four strains of two yeast species in relation to their capability for assimilating alkanes in the presence of heavy metals (HMs). The four strains tested were Candida pseudoglaebosa ENCB-7 and Kodamaea ohmeri ENCB-8R, ENCB-23, and ENCB-VIK. Determination was made of the expression of CYP52 genes involved in alkane hydroxylation. When exposed to Cu2+ , Zn2+ , Pb2+ , Cd2+ , and As3+ at pH 3 and 5, all four strains could assimilate several n-alkanes having at least six carbon atoms. The three K. ohmeri strains could also utilize branched alkanes, cycloalkanes, and n-octanol as sole carbon sources. Kinetic assays demonstrated greater biomass production and specific growth of the yeasts exposed to long-chain n-alkanes. Fragments of paralogous CYP52 genes of C. pseudoglaebosa ENCB-7 and K. ohmeri ENCB-23 were amplified, sequenced, and phylogenetically evaluated. Reverse-transcription polymerase chain reaction revealed that n-nonane and n-decane induced to CpCYP52-G3, CpCYP52-G9, and CpCYP52-G10. KoCYP52-G3 was induced with n-decane and n-octanol. Also, CpCYP52-G3 and CpCYP52-G9 were induced by glucose. In conclusion, C. pseudoglaebosa and K. ohmeri were able to degrade several alkanes in the presence of HMs and under acidic conditions. These yeasts harbor paralogous alkane-induced CYP52 genes, which display different profiles of transcriptional expression.


Assuntos
Alcanos/metabolismo , Metais Pesados/metabolismo , Saccharomycetales/metabolismo , Alcanos/química , Biodegradação Ambiental , Biomassa , Candida/classificação , Candida/genética , Candida/crescimento & desenvolvimento , Candida/metabolismo , Sistema Enzimático do Citocromo P-450/genética , DNA Ribossômico/genética , Proteínas Fúngicas/genética , Concentração de Íons de Hidrogênio , Cinética , Filogenia , Saccharomycetales/classificação , Saccharomycetales/genética , Saccharomycetales/crescimento & desenvolvimento
10.
Nat Commun ; 10(1): 3549, 2019 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-31391466

RESUMO

The asymmetric cross-coupling reaction is developed as a straightforward strategy toward 1,1-diaryl alkanes, which are a key skeleton in a series of natural products and bioactive molecules in recent years. Here we report an enantioselective benzylic C(sp3)-H bond arylation via photoredox/nickel dual catalysis. Sterically hindered chiral biimidazoline ligands are designed for this asymmetric cross-coupling reaction. Readily available alkyl benzenes and aryl bromides with various functional groups tolerance can be easily and directly transferred to useful chiral 1,1-diaryl alkanes including pharmaceutical intermediates and bioactive molecules. This reaction proceeds smoothly under mild conditions without the use of external redox reagents.


Assuntos
Alcanos/química , Produtos Biológicos/química , Níquel/química , Processos Fotoquímicos , Brometos/química , Catálise/efeitos da radiação , Elétrons , Luz , Oxirredução , Estereoisomerismo
11.
Chemosphere ; 236: 124387, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31336240

RESUMO

The treatment of wastewater containing hydrophobic organic pollutants solubilized by surfactants is of great environmental importance. In this work, the removal of rhamnolipid-solubilized hexadecane via a salicylic acid-methanol-acetone modified steel converter slag (SMA-SCS) catalyzed Fenton-like process was studied. First, we investigated the adsorption of rhamnolipid and hexadecane onto SCS and SMA-modified SCS. Compared to that of SCS, SMA-SCS exhibited better adsorption performance with maximum adsorption capacities of 0.23 and 0.28 mg/g for hexadecane and rhamnolipid, respectively. Degradation experiments showed that hexadecane was more readily degraded by the Fenton-like process than rhamnolipid. Up to 81.1% of hexadecane removal was achieved over 20 g/L of SMA-SCS within 24 h, whereas only 36% of rhamnolipid was degraded. On the other hand, the results indicated that increased rhamnolipid concentration had a negative effect on the degradation of hexadecane. During the oxidation reaction, the pH value of solution remained between 6.0 and 6.72. All these results demonstrated that the SMA-SCS/H2O2 Fenton-like process could be a cost-effective and promising approach for the treatment of surfactant-solubilized hydrophobic organic compounds.


Assuntos
Alcanos/química , Glicolipídeos/química , Águas Residuárias/química , Catálise
12.
Int J Biol Macromol ; 136: 944-950, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31229548

RESUMO

Microorganisms often grow in communities called biofilms where cells are imbedded in a complex self-produced biopolymeric matrix composed mainly of polysaccharides, proteins, and DNA. This matrix, together with cell proximity, confers many advantages to these microbial communities, but also constitutes a serious concern when biofilms develop in human tissues or on implanted prostheses. Although polysaccharides are considered the main constituents of the matrices, their specific role needs to be clarified. We have investigated the chemical and morphological properties of the polysaccharide extracted from biofilms produced by the C1576 reference strain of the opportunistic pathogen Burkholderia multivorans, which causes lung infections in cystic fibrosis patients. The aim of the present study is the definition of possible interactions of the polysaccharide and the three-dimensional conformation of its chain within the biofilm matrix. Surface plasmon resonance experiments confirmed the ability of the polysaccharide to bind hydrophobic molecules, due to the presence of rhamnose dimers in its primary structure. In addition, atomic force microscopy studies evidenced an extremely compact three-dimensional structure of the polysaccharide which may form aggregates, suggesting a novel view of its structural role into the biofilm matrix.


Assuntos
Alcanos/química , Biofilmes , Burkholderia/química , Burkholderia/fisiologia , Interações Hidrofóbicas e Hidrofílicas , Polissacarídeos Bacterianos/química , Polissacarídeos Bacterianos/isolamento & purificação , Configuração de Carboidratos , Dimerização , Ressonância de Plasmônio de Superfície
13.
J Chromatogr A ; 1603: 297-310, 2019 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-31227363

RESUMO

Surface modification of porous glass beads by ethanol-based 3-mercaptopropyltrimethoxysilane (MPTMS) grafting solutions is directly evidenced by nitrogen adsorption, elemental analysis, thermogravimetry, infrared and 29Si CP MAS NMR spectroscopy. Furthermore, the energetic characterization of the surface is essential to understand comprehensively the physico-chemical interactions between the pristine and MPTMS-modified surface and its gas/liquid-phase environment. In this study, inverse gas chromatography (IGC) is used to characterize the surface properties of porous glass (PG). By means of IGC at infinite dilution (IGC-ID), the dispersive component of the surface energy (γsd), the enthalpy and entropy of adsorption of C6-C10 hydrocarbon probes were determined at temperatures between 30 and 120 °C. The specific component of the surface energy (γssp) at the temperature of 120 °C has been obtained via the Van Oss theory and a least-squares procedure evaluating the IGC data of 8 polar probe molecules collectively. After surface silylation, the total surface energy (γst) decreased from 402 to 255 mJ/m² indicating both a reduced wettability and an increased hydrophobicity of the MPTMS-modified PG. Moreover, the acidity/basicity parameters according to the Van Oss and the Gutmann approach indicated that the acidity of the PG surface decreases by MPTMS grafting. Using n-octane and isopropanol probes, IGC at finite concentration (IGC-FC) was applied to obtain their adsorption isotherms and subsequently the BET specific surface areas. In addition, the surface heterogeneity of the studied PGs was also computed. The energy distribution functions of adsorption sites were monomodal (peak maximum at about 22 kJ/mol) for the n-octane probe, while isopropanol revealed a bimodal distribution function (maxima at about 18 and 25 kJ/mol) on both pristine and MPTMS-modified PG. Furthermore, the proportion of high energy sites (apparently assigned to SiOH groups) has been reduced by surface modification from 65% to only 35% despite a high surface coverage of ˜10 MPTMS species/nm2. These findings are in agreement with the results of 29Si CP MAS NMR measurements and are supported by DFT calculations on the adsorption of isopropanol and n-octane on the surface of a silica cluster model.


Assuntos
Cromatografia Gasosa/métodos , Dióxido de Silício/química , 2-Propanol/química , Ácidos/química , Adsorção , Alcanos/química , Teoria da Densidade Funcional , Entropia , Espectroscopia de Ressonância Magnética , Conformação Molecular , Nitrogênio/química , Porosidade , Silanos/química , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Temperatura Ambiente , Termogravimetria
14.
Chemosphere ; 228: 762-768, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31075639

RESUMO

Chlorinated paraffins (CPs) are complex mixtures of polychlorinated n-alkanes of different chain length. Despite their environmental relevance, quantification is still a challenge. Moreover, the individual structures of the molecules in technical CP mixtures are largely unknown. Here, we synthesized 21 and studied 29 single chain length CP mixtures ranging from C10- to C17-CPs with different chlorine contents between 41.8% and 62.6% Cl and analyzed them by means of nuclear magnetic resonance spectroscopy (NMR). Discrete ranges of chemical shifts were observed in one-dimensional 1H and 13C NMR spectra. Two dimensional heteronuclear single quantum coherence spectroscopy (HSQC) enabled to assign nine substructures. These measurements also verified the presence of [-CCl2-] groups and chlorine atoms on terminal carbons in highly chlorinated (>59% Cl) mixtures. 1H NMR spectra of different chain length and the same degree of chlorination looked virtually the same. However, with increasing degree of chlorination the observed patterns in the spectra were slightly shifted downfield. Based on these findings, a calculation mode was developed to estimate the chlorine content (%) of the single chain length CP mixtures. The results agreed well (<0.9% mean deviation) with parallel measurements by elemental analysis.


Assuntos
Espectroscopia de Ressonância Magnética/métodos , Parafina/análise , Parafina/química , Alcanos/química , Cloro/análise , Cloro/química , Halogenação , Hidrocarbonetos Clorados/análise , Hidrocarbonetos Clorados/química
15.
Eur Biophys J ; 48(5): 447-455, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31089758

RESUMO

We set out to explore the applicability of small-angle neutron diffraction (SAND) to the localization of biomembrane components by studying the general anesthetic n-decane in a model lipid bilayer system composed of dioleoyl-phosphocholine (DOPC). Samples in the form of planar membrane multilayers were hydrated by varied mixtures of deuterated and protonated water, and examined by the means of SAND. Neutron scattering length density (NSLD) profiles of the system were then reconstructed from the experimental data. We exploited the significantly different neutron scattering properties of hydrogen and deuterium atoms via labeling in addition to water contrast variation. Enhancing the signals from particular components of bilayer system led to a set of characteristic membrane profiles and from their comparison we localized n-decane molecules unequivocally in the bilayer's hydrocarbon chain region.


Assuntos
Anestésicos Gerais/química , Bicamadas Lipídicas/química , Difração de Nêutrons , Espalhamento a Baixo Ângulo , Alcanos/química
16.
J Chromatogr A ; 1599: 239-246, 2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-31005291

RESUMO

This work reports a new type of triptycene-based amphiphilic stationary phase (TP-2IL) for gas chromatography (GC). It is an integration of the 3D π-rich triptycene framework with ionic liquids. Its capillary column showed the efficiency of 3880 plates/m determined by n-dodecane at 120 °C (k = 2.79) and exhibited good performance for analytes from apolar to polar nature. Particularly, it has outstanding capability for resolving critical pairs of anilines and phenols with good peak shapes and shows distinct advantages over its composing counterparts (TP-2BO and O-IL) and widely-used commercial columns, namely 35% phenyl methyl polysiloxane (DB-35) and polyethylene glycol (INNOWAX). Moreover, the TP-2IL column exhibited good repeatability and reproducibility with the values of relative standard deviation in the range of 0.02%-0.07% for run-to-run, 0.10%-0.35% for day-to-day and 2.9%-5.1% for column-to-column, respectively, and good thermal stability up to 300 °C. Furthermore, its applications for determining isomer impurities in real samples demonstrate its feasibility for practical GC analysis. This work presents a facile strategy for constructing triptycene-based stationary phases with amphiphilic selectivity and provides alternatives of highly selective stationary phases for chromatographic analysis.


Assuntos
Antracenos/química , Técnicas de Química Analítica/instrumentação , Técnicas de Química Analítica/métodos , Cromatografia Gasosa , Alcanos/química , Compostos de Anilina/isolamento & purificação , Isomerismo , Fenóis/isolamento & purificação , Reprodutibilidade dos Testes , Siloxanas
17.
Molecules ; 24(5)2019 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-30845646

RESUMO

Microencapsulated phase change materials (MicroPCMs)-incorporated in epoxy composites have drawn increasing interest due to their promising application potential in the fields of thermal energy storage and temperature regulation. However, the study on the effect of MicroPCMs on their microstructure, thermal and viscoelastic properties is quite limited. Herein, a new type of smart epoxy composite incorporated with polyurea (PU)-shelled MicroPCMs was fabricated via solution casting method. Field emission-scanning electron microscope (FE-SEM) images revealed that the MicroPCMs were uniformly distributed in the epoxy matrix. The thermal stabilities, conductivities, phase change properties, and dynamic mechanical behaviors of the composite were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), thermal constant analyzer and infrared thermography. The results suggested that the heat storage ability of the composites was improved by increasing the MicroPCMs content. The thermal stability of MicroPCMs was found to be enhanced after incorporation into the matrix, and the MicroPCMs-incorporated epoxy composites showed a good thermal cycling reliability. Moreover, the incorporation of MicroPCMs reduced the composites' storage modulus but increased the glass transition temperature (Tg) as a result of their restriction to the chain motion of epoxy resin. Besides, a less marked heating effect for the composite was explored through infrared thermography analysis, demonstrating the good prospect for temperature regulation application.


Assuntos
Cápsulas/síntese química , Resinas Epóxi/química , Transição de Fase , Alcanos/química , Emulsões/química , Temperatura Alta , Cinética , Teste de Materiais/métodos , Fenômenos Mecânicos , Tamanho da Partícula , Reprodutibilidade dos Testes , Propriedades de Superfície , Temperatura Ambiente , Termodinâmica
18.
Nat Microbiol ; 4(4): 595-602, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30833728

RESUMO

Methanogenesis and anaerobic methane oxidation through methyl-coenzyme M reductase (MCR) as a key enzyme have been suggested to be basal pathways of archaea1. How widespread MCR-based alkane metabolism is among archaea, where it occurs and how it evolved remain elusive. Here, we performed a global survey of MCR-encoding genomes based on metagenomic data from various environments. Eleven high-quality mcr-containing metagenomic-assembled genomes were obtained belonging to the Archaeoglobi in the Euryarchaeota, Hadesarchaeota and different TACK superphylum archaea, including the Nezhaarchaeota, Korarchaeota and Verstraetearchaeota. Archaeoglobi WYZ-LMO1 and WYZ-LMO3 and Korarchaeota WYZ-LMO9 encode both the (reverse) methanogenesis and the dissimilatory sulfate reduction pathway, suggesting that they have the genomic potential to couple both pathways in individual organisms. The Hadesarchaeota WYZ-LMO4-6 and Archaeoglobi JdFR-42 encode highly divergent MCRs, enzymes that may enable them to thrive on non-methane alkanes. The occurrence of mcr genes in different archaeal phyla indicates that MCR-based alkane metabolism is common in the domain of Archaea.


Assuntos
Alcanos/metabolismo , Archaea/classificação , Archaea/metabolismo , Alcanos/química , Archaea/química , Archaea/genética , Proteínas Arqueais/genética , Proteínas Arqueais/metabolismo , Metano/metabolismo , Filogenia
19.
Nat Microbiol ; 4(4): 603-613, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30833729

RESUMO

Methanogenesis is an ancient metabolism of key ecological relevance, with direct impact on the evolution of Earth's climate. Recent results suggest that the diversity of methane metabolisms and their derivations have probably been vastly underestimated. Here, by probing thousands of publicly available metagenomes for homologues of methyl-coenzyme M reductase complex (MCR), we have obtained ten metagenome-assembled genomes (MAGs) belonging to potential methanogenic, anaerobic methanotrophic and short-chain alkane-oxidizing archaea. Five of these MAGs represent under-sampled (Verstraetearchaeota, Methanonatronarchaeia, ANME-1 and GoM-Arc1) or previously genomically undescribed (ANME-2c) archaeal lineages. The remaining five MAGs correspond to lineages that are only distantly related to previously known methanogens and span the entire archaeal phylogeny. Comprehensive comparative annotation substantially expands the metabolic diversity and energy conservation systems of MCR-bearing archaea. It also suggests the potential existence of a yet uncharacterized type of methanogenesis linked to short-chain alkane/fatty acid oxidation in a previously undescribed class of archaea ('Candidatus Methanoliparia'). We redefine a common core of marker genes specific to methanogenic, anaerobic methanotrophic and short-chain alkane-oxidizing archaea, and propose a possible scenario for the evolutionary and functional transitions that led to the emergence of such metabolic diversity.


Assuntos
Alcanos/química , Archaea/metabolismo , Biodiversidade , Metano/metabolismo , Alcanos/metabolismo , Archaea/classificação , Archaea/genética , Archaea/crescimento & desenvolvimento , DNA Arqueal , Metagenoma , Metano/química , Oxirredução , Filogenia
20.
Microb Cell Fact ; 18(1): 20, 2019 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-30704481

RESUMO

BACKGROUND: Long-chain free fatty acids (FFAs) are a type of backbone molecule that can react with alcohol to produce biodiesels. Various microorganisms have become potent producers of FFAs. Efforts have focused on increasing metabolic flux to the synthesis of either neutral fat or fatty acyl intermediates attached to acyl carrier protein (ACP), which are the source of FFAs. Membrane lipids are also a source of FFAs. As an alternative way of producing FFAs, exogenous phospholipase may be used after heterologous production and localization in the periplasmic space. In this work, we examined whether Rhodobacter sphaeroides, which forms an intracytoplasmic membrane, can be used for long-chain FFA production using phospholipase. RESULTS: The recombinant R. sphaeroides strain Rs-A2, which heterologously produces Arabidopsis thaliana phospholipase A2 (PLA2) in the periplasm, excretes FFAs during growth. FFA productivity under photoheterotrophic conditions is higher than that observed under aerobic or semiaerobic conditions. When the biosynthetic enzymes for FA (ß-ketoacyl-ACP synthase, FabH) and phosphatidate (1-acyl-sn-glycerol-3-phosphate acyltransferase, PlsC) were overproduced in Rs-A2, the FFA productivity of the resulting strain Rs-HCA2 was elevated, and the FFAs produced mainly consisted of long-chain FAs of cis-vaccenate, stearate, and palmitate in an approximately equimolar ratio. The high-cell-density culture of Rs-HCA2 with DMSO in two-phase culture with dodecane resulted in an increase of overall carbon substrate consumption, which subsequently leads to a large increase in FFA productivity of up to 2.0 g L-1 day-1. Overexpression of the genes encoding phosphate acyltransferase (PlsX) and glycerol-3-phosphate acyltransferase (PlsY), which catalyze the biosynthetic steps immediately upstream from PlsC, in Rs-HCA2 generated Rs-HXYCA2, which grew faster than Rs-HCA2 and showed an FFA productivity of 2.8 g L-1 day-1 with an FFA titer of 8.5 g L-1. CONCLUSION: We showed that long-chain FFAs can be produced from metabolically engineered R. sphaeroides heterologously producing PLA2 in the periplasm. The FFA productivity was greatly increased by high-cell-density culture in two-phase culture with dodecane. This approach provides highly competitive productivity of long-chain FFAs by R. sphaeroides compared with other bacteria. This method may be applied to FFA production by other photosynthetic bacteria with similar differentiated membrane systems.


Assuntos
Alcanos/química , Ácidos Graxos não Esterificados/biossíntese , Periplasma/enzimologia , Fosfolipases A2/metabolismo , Rhodobacter sphaeroides/metabolismo , Lipídeos de Membrana/metabolismo , Engenharia Metabólica , Rhodobacter sphaeroides/genética
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