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1.
Gigascience ; 112022 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-35946988

RESUMO

BACKGROUND: Studies in vertebrate genomics require sampling from a broad range of tissue types, taxa, and localities. Recent advancements in long-read and long-range genome sequencing have made it possible to produce high-quality chromosome-level genome assemblies for almost any organism. However, adequate tissue preservation for the requisite ultra-high molecular weight DNA (uHMW DNA) remains a major challenge. Here we present a comparative study of preservation methods for field and laboratory tissue sampling, across vertebrate classes and different tissue types. RESULTS: We find that storage temperature was the strongest predictor of uHMW fragment lengths. While immediate flash-freezing remains the sample preservation gold standard, samples preserved in 95% EtOH or 20-25% DMSO-EDTA showed little fragment length degradation when stored at 4°C for 6 hours. Samples in 95% EtOH or 20-25% DMSO-EDTA kept at 4°C for 1 week after dissection still yielded adequate amounts of uHMW DNA for most applications. Tissue type was a significant predictor of total DNA yield but not fragment length. Preservation solution had a smaller but significant influence on both fragment length and DNA yield. CONCLUSION: We provide sample preservation guidelines that ensure sufficient DNA integrity and amount required for use with long-read and long-range sequencing technologies across vertebrates. Our best practices generated the uHMW DNA needed for the high-quality reference genomes for phase 1 of the Vertebrate Genomes Project, whose ultimate mission is to generate chromosome-level reference genome assemblies of all ∼70,000 extant vertebrate species.


Assuntos
Benchmarking , Dimetil Sulfóxido , Animais , DNA/genética , Ácido Edético , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Peso Molecular , Análise de Sequência de DNA/métodos
2.
Molecules ; 27(15)2022 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-35956840

RESUMO

Molecular interaction analysis is an essential technique for the study of biomolecular functions and the development of new drugs. Most current methods generally require manipulation to immobilize or label molecules, and require advance identification of at least one of the two molecules in the reaction. In this study, we succeeded in detecting the interaction of low-molecular-weight (LMW) compounds with a membrane protein mixture derived from cultured cells expressing target membrane proteins by using the size exclusion chromatography-mass spectrometry (SEC-MS) method under the condition of 0.001% lauryl maltose neopentyl glycol as detergent and atmospheric pressure chemical ionization. This method allowed us to analyze the interaction of a mixture of medicinal herbal ingredients with a mixture of membrane proteins to identify the two interacting ingredients. As it does not require specialized equipment (e.g., a two-dimensional liquid chromatography system), this SEC-MS method enables the analysis of interactions between LMW compounds and relatively high-expressed membrane proteins without immobilization or derivatization of the molecules.


Assuntos
Proteínas de Membrana , Cromatografia em Gel , Cromatografia Líquida/métodos , Espectrometria de Massas/métodos , Peso Molecular
3.
Top Curr Chem (Cham) ; 380(5): 45, 2022 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-35951265

RESUMO

Glycopolymer materials have emerged as a significant biopolymer class that has piqued the scientific community's attention due to their potential applications. Recently, they have been found to be a unique synthetic biomaterial; glycopolymer materials have also been used for various applications, including direct therapeutic methods, medical adhesives, drug/gene delivery systems, and biosensor applications. Therefore, for the next stage of biomaterial research, it is essential to understand current breakthroughs in glycopolymer-based materials research. This review discusses the most widely utilized synthetic methodologies for glycopolymer-based materials, their properties based on structure-function interactions, and the significance of these materials in biosensing applications, among other topics. When creating glycopolymer materials, contemporary polymerization methods allow precise control over molecular weight, molecular weight distribution, chemical activity, and polymer architecture. This review concludes with a discussion of the challenges and complexities of glycopolymer-based biosensors, in addition to their potential applications in the future.


Assuntos
Técnicas Biossensoriais , Polímeros , Materiais Biocompatíveis , Peso Molecular , Polimerização , Polímeros/química
4.
Int J Mol Sci ; 23(15)2022 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-35955592

RESUMO

In a previous study, we found that administration of ILB®, a new low molecular weight dextran sulphate, significantly improved mitochondrial functions and energy metabolism, as well as decreased oxidative/nitrosative stress, of brain tissue of rats exposed to severe traumatic brain injury (sTBI), induced by the closed-head weight-drop model of diffused TBI. Using aliquots of deproteinized brain tissue of the same animals of this former study, we here determined the concentrations of 24 amino acids of control rats, untreated sTBI rats (sacrificed at 2 and 7 days post-injury) and sTBI rats receiving a subcutaneous ILB® administration (at the dose levels of 1, 5 and 15 mg/kg b.w.) 30 min post-impact (sacrificed at 2 and 7 days post-injury). Additionally, in a different set of experiments, new groups of control rats, untreated sTBI rats and ILB®-treated rats (administered 30 min after sTBI at the dose levels of 1 or 5 mg/kg b.w.) were studied for their neurocognitive functions (anxiety, locomotor capacities, short- and long-term memory) at 7 days after the induction of sTBI. Compared to untreated sTBI animals, ILB® significantly decreased whole brain glutamate (normalizing the glutamate/glutamine ratio), glycine, serine and γ-aminobutyric acid. Furthermore, ILB® administration restored arginine metabolism (preventing nitrosative stress), levels of amino acids involved in methylation reactions (methionine, L-cystathionine, S-adenosylhomocysteine), and N-acetylaspartate homeostasis. The macroscopic evidences of the beneficial effects on brain metabolism induced by ILB® were the relevant improvement in neurocognitive functions of the group of animals treated with ILB® 5 mg/kg b.w., compared to the marked cognitive decline measured in untreated sTBI animals. These results demonstrate that ILB® administration 30 min after sTBI prevents glutamate excitotoxicity and normalizes levels of amino acids involved in crucial brain metabolic functions. The ameliorations of amino acid metabolism, mitochondrial functions and energy metabolism in ILB®-treated rats exposed to sTBI produced significant improvement in neurocognitive functions, reinforcing the concept that ILB® is a new effective therapeutic tool for the treatment of sTBI, worth being tested in the clinical setting.


Assuntos
Lesões Encefálicas Traumáticas , Sulfatos , Aminoácidos/metabolismo , Animais , Lesões Encefálicas Traumáticas/tratamento farmacológico , Lesões Encefálicas Traumáticas/metabolismo , Sulfato de Dextrana , Ácido Glutâmico , Homeostase , Peso Molecular , Ratos
5.
Sci Rep ; 12(1): 13227, 2022 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-35918482

RESUMO

Biodegradation of high-molecular-weight petroleum hydrocarbons in saline conditions appears to be complicated and requires further investigation. This study used heavy crude oil to enrich petroleum-degrading bacteria from oil-contaminated saline soils. Strain HG 01, with 100% sequence similarity to Bacillus subtilis, grew at a wide range of salinities and degraded 55.5 and 77.2% of 500 mg/l pyrene and 500 mg/l tetracosane, respectively, at 5% w/v NaCl. Additionally, a mixed-culture of HG 01 with Pseudomonas putida and Pseudomonas aeruginosa, named TMC, increased the yield of pyrene, and tetracosane degradation by about 20%. Replacing minimal medium with treated seawater (C/N/P adjusted to 100/10/1) enabled TMC to degrade more than 99% of pyrene and tetracosane, but TMC had lesser degradation in untreated seawater than in minimal medium. Also, the degradation kinetics of pyrene and tetracosane were fitted to a first-order model. Compared to B. subtilis, TMC increased pyrene and tetracosane's removal rate constant (K1) from 0.063 and 0.110 per day to 0.123 and 0.246 per day. TMC also increased the maximum specific growth rate of B. subtilis, P. putida, and P. aeruginosa, respectively, 45% higher in pyrene, 24.5% in tetracosane, and 123.4% and 95.4% higher in pyrene and tetracosane.


Assuntos
Bacillus subtilis , Petróleo , Bacillus subtilis/metabolismo , Biodegradação Ambiental , Hidrocarbonetos/metabolismo , Peso Molecular , Petróleo/metabolismo , Pseudomonas/metabolismo , Pseudomonas aeruginosa/metabolismo , Pirenos/metabolismo
6.
Adv Exp Med Biol ; 1400: 129-138, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35930231

RESUMO

The mass spectrometer is an instrument that observes particular masses of molecules of interest. Over the past century, it has grown to become a highly sensitive and robust tool in laboratorial and clinical research to identify and quantify thousands of proteins in a given sample in an unbiased manner leading to the quick rise in its use. This unbiased and high-throughput nature is extremely important in discovery-based studies, since no preset targets can be selected, as is the case with several other proteomic methods. In studying multifactorial diseases such as schizophrenia, mass-spectrometry-based proteomics has been frequently used and new improvements to the technique have been quickly taken advantage of. Over the past 15 years, mass spectrometry has evolved greatly, and with it, the proteomic analyses and data have evolved. In this chapter, a brief history of the evolution of mass spectrometry is covered along with how schizophrenia research has grown alongside this valuable methodology.


Assuntos
Proteômica , Esquizofrenia , Humanos , Espectrometria de Massas/métodos , Peso Molecular , Proteômica/métodos , Esquizofrenia/diagnóstico
7.
Chemosphere ; 305: 135542, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35777542

RESUMO

The photochemical properties of dissolved organic matter (DOM) were highly related to the molecular weight (MW) and organic compositions. In this study, the bulk algae- and macrophyte-derived DOM (ADOM and MDOM, respectively) and Suwannee River humic acid (SRHA) were applied and fractionated into low MW- (LMW, <1 kDa) and high MW-(HMW-, 1 kDã0.45 µm) fractions. The formation and mechanisms of photochemically produced reactive intermediates (e.g., HO•, 1O2, and 3CDOM*) for these bulk and MW-fractionated samples were compared via the irradiation experiment, fluorescence and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Results showed that humic-/fulvic-like substances were mainly distributed in the LMW fraction which occupied about 44-60% of total organic carbon for ADOM and MDOM and 13% for SRHA. Photochemical experiments showed that the autochthonous DOMs (e.g., ADOM and MDOM) were characterized with comparable formation rates and quantum yields of reactive oxygens with the allochthonous SRHA, suggesting the high photochemical formation potential. Further analysis showed obvious MW-dependent heterogeneities that, irrespective of DOM types, the LMW-fraction exhibited higher formation rates and quantum yields, followed by the bulk- and then the HMW-fractions. The fluorescence and FT-ICR-MS results indicated that the unique biochemical classes, i.e., humic-/fulvic-like moieties and protein-/lipid-derived compounds in the LMW fractions may be responsible for the high apparent quantum yields. This study highlighted the importance of simultaneous characterization of MW and organic compositions for evaluating the photochemical potential and other behaviors and effects of aquatic DOMs.


Assuntos
Matéria Orgânica Dissolvida , Processos Fotoquímicos , Substâncias Húmicas/análise , Peso Molecular , Oxigênio/análise
8.
Food Chem ; 395: 133605, 2022 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-35802976

RESUMO

In this work, the film-forming properties of chitosan with different molecular weights (MW) (30, 100, 200 and 300 kDa) and its adhesion properties with different postharvest fruit surfaces were analyzed. The viscosity of 30 and 300 kDa chitosan film-forming solution gradually increased from 0.007 to 1.16 Pa.s at a shear rate of 10 s-1. Compared to 30 kDa chitosan films, higher MW chitosan films showed enhanced water resistance, water vapor barrier properties and mechanical properties, mainly due to the different strength of interaction forces within the chitosan films, which can be confirmed by microstructural observations and FTIR results of the films. It can be found that different MW chitosan film surfaces with bananas, apples, pears, oranges and strawberries all have a similar adhesion work of about 70-80 mN m-1, and 100 and 200 kDa chitosan film had higher adhesion work with different fruit surfaces compared to 30 and 300 kDa.


Assuntos
Quitosana , Pyrus , Quitosana/química , Frutas/química , Peso Molecular , Vapor/análise
9.
Food Chem ; 395: 133599, 2022 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-35802980

RESUMO

To provide additional evidence and better understand the high-moisture texturing extrusion process of soybean protein isolate (SPI), the physico-chemical changes of SPI during extrusion were investigated. SPI in the extruder feeding zone, barrel zones 1 (80 °C) to 4 (135 °C), and the cooling die (80 °C) were obtained from a dead-stop operation. The lowest values associated with the denaturation enthalpy and the extractable protein occurred in zone 3 (150 °C). The minimum level of the protein subunit content was identified in zone 4. The highest value of the average protein molar mass occurred in zone 3. The ß-sheet ratio in the protein increased, and the unordered ratio decreased after extrusion. The surface hydrophobicity of the protein decreased with water injection in zone 1; however, it increased in zone 2 (110 °C). Overall, SPI undergoes swelling, denaturation, aggregation, and depolymerization due to water injection, heating, and shearing during high-moisture extrusion.


Assuntos
Proteínas de Soja , Água , Interações Hidrofóbicas e Hidrofílicas , Peso Molecular , Água/química
10.
Antonie Van Leeuwenhoek ; 115(9): 1101-1112, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35840814

RESUMO

A new exopolysaccharide (EPS) producing Gram-positive bacterium was isolated from the rhizosphere of Bouteloua dactyloides (buffalo grass) and its EPS product was structurally characterized. The isolate, designated as LB1-1A, was identified as Bacillus paralicheniformis based on 16S rRNA gene sequence and phylogenetic tree analysis. The EPS produced by LB1-1A was identified as a levan, having ß(2 → 6) linked backbone with ß(2 → 1) linkages at the branch points (4.66%). The isolate LB1-1A yielded large amount (~ 42 g/l) of levan having high weight average molecular weight (Mw) of 5.517 × 107 Da. The relatively low degree of branching and high molecular weight of this levan makes B. paralicheniformis LB1-1A a promising candidate for industrial applications.


Assuntos
Frutanos , Rizosfera , Bacillus , Peso Molecular , Filogenia , Poaceae , RNA Ribossômico 16S/genética
11.
Bioorg Chem ; 127: 106000, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35853296

RESUMO

In the last decade, emerging evidence has shown that low molecular weight protein tyrosine phosphatase (LMWPTP) not only contributes to the progression of cancer but is associated with prostate low survival rate and colorectal cancer metastasis. We report that LMWPTP favors the glycolytic profile in some tumors. Therefore, the focus of the present study was to identify metabolic enzymes that correlate with LMWPTP expression in patient samples. Exploratory data analysis from RNA-seq, proteomics, and histology staining, confirmed the higher expression of LMWPTP in CRC. Our descriptive statistical analyses indicate a positive expression correlation between LMWPTP and energy metabolism enzymes such as acetyl-CoA carboxylase (ACC) and fatty acid synthase (FASN). In addition, we examine the potential of violacein to reprogram energetic metabolism and LMWPTP activity. Violacein treatment induced a shift of glycolytic to oxidative metabolism associated with alteration in mitochondrial efficiency, as indicated by higher oxygen consumption rate. Particularly, violacein treated cells displayed higher proton leak and ATP-linked oxygen consumption rate (OCR) as an indicator of the OXPHOS preference. Notably, violacein is able to bind and inhibit LMWPTP. Since the LMWPTP acts as a hub of signaling pathways that offer tumor cells invasive advantages, such as survival and the ability to migrate, our findings highlight an unexplored potential of violacein in circumventing the metabolic plasticity of tumor cells.


Assuntos
Neoplasias Colorretais , Proteínas Tirosina Fosfatases , Neoplasias Colorretais/patologia , Humanos , Indóis , Masculino , Mitocôndrias/metabolismo , Peso Molecular , Proteínas Tirosina Fosfatases/metabolismo , Tirosina
12.
Int J Mol Sci ; 23(14)2022 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-35886948

RESUMO

Chitin is the most widespread amino renewable carbohydrate polymer in nature and the second most abundant polysaccharide. Therefore, chitin and chitinolytic enzymes are becoming more importance for biotechnological applications in food, health and agricultural fields, the design of effective enzymes being a paramount issue. We report the crystal structure of the plant-type endo-chitinase Chit33 from Trichoderma harzianum and its D165A/E167A-Chit33-(NAG)4 complex, which showed an extended catalytic cleft with six binding subsites lined with many polar interactions. The major trait of Chit33 is the location of the non-conserved Asp117 and Arg274 acting as a clamp, fixing the distorted conformation of the sugar at subsite -1 and the bent shape of the substrate, which occupies the full catalytic groove. Relevant residues were selected for mutagenesis experiments, the variants being biochemically characterized through their hydrolytic activity against colloidal chitin and other polymeric substrates with different molecular weights and deacetylation percentages. The mutant S118Y stands out, showing a superior performance in all the substrates tested, as well as detectable transglycosylation capacity, with this variant providing a promising platform for generation of novel Chit33 variants with adjusted performance by further design of rational mutants'. The putative role of Tyr in binding was extrapolated from molecular dynamics simulation.


Assuntos
Quitinases , Catálise , Quitina/metabolismo , Quitinases/metabolismo , Peso Molecular , Especificidade por Substrato
13.
Chem Commun (Camb) ; 58(63): 8736-8753, 2022 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-35861166

RESUMO

Supramolecular gels, as a fascinating and useful class of soft materials, constructed from low-molecular-weight gelators via noncovalent interactions have attracted increasing attention in the past few decades. Dendrimers and dendrons are highly branched and monodisperse macromolecules with a well-defined three-dimensional architecture and multiple surface functionalities. In recent years, poly(benzyl ether) dendrimers and dendrons are found to be powerful candidates for constructing gel phase materials in organic or aqueous media due to the advantages of capability of forming multiple noncovalent interactions and significant steric impact. In this Feature Article, we provide a comprehensive overview of recent progress in supramolecular gels involving poly(benzyl ether) dendritic molecules. Firstly, we outline the molecular design strategies of dendritic gelators with an emphasis on the discussion of their gelating units and position in molecular structures. Subsequently, we discuss the potential applications of dendritic gels in light harvesting, stimuli responsive materials, sensors and environmental remediation. In addition, the potential challenges and future perspectives of poly(benzyl ether) dendritic gels have also been discussed. It is hoped that this feature article will attract increasing attention and provide some valuable insights for the future design and evolution of supramolecular gels.


Assuntos
Dendrímeros , Dendrímeros/química , Éter/química , Géis/química , Estrutura Molecular , Peso Molecular
14.
Molecules ; 27(13)2022 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-35807226

RESUMO

The isolation of chitin utilizing ionic liquid 1-ethyl-3-methylimidazolium acetate has been determined to result in polymer contaminated with proteins. For the first time, the proteins in chitin extracted with ionic liquid have been quantified; the protein content was found to vary from 1.3 to 1.9% of the total weight. These proteins were identified and include allergenic proteins such as tropomyosin. In order to avoid 'traditional' hydroxide-based deproteinization of chitin, which could reduce the molecular weight of the final product, alternative deproteinization strategies were attempted. Testing of the previously reported deproteinization method using aqueous K3PO4 resulted in protein reduction by factors varying from 2 to 10, but resulted in significant phosphate salt contamination of the final product. Contrarily, the incorporation of GRAS (Generally Recognized as Safe) compound Polysorbate 80 into the polymer washing step provided the polymer of comparable purity with no contaminants. This study presents new options for the deproteinization of chitin that can replace traditional approaches with methods that are environmentally friendly and can produce high purity polymer.


Assuntos
Quitina , Líquidos Iônicos , Peso Molecular , Polímeros , Proteínas
15.
Molecules ; 27(13)2022 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-35807439

RESUMO

The structural characterization, the in vitro antioxidant activity, and the hypoglycemic activity of a polysaccharide (SGP-1-1) isolated from Siraitia grosvenorii (SG) were studied in this paper. SGP-1-1, whose molecular weight is 19.037 kDa, consisted of Gal:Man:Glc in the molar ratio of 1:2.56:4.90. According to the results of methylation analysis, GC-MS, and NMR, HSQC was interpreted as a glucomannan with a backbone composed of 4)-ß-D-Glcp-(1→4)-, α-D-Glcp-(1→4)-, and 4)-Manp-(1 residues. α-1,6 linked an α-D-Galp branch, and α-1,6 linked an α-D-Glcp branch. The study indirectly showed that SGP-1-1 has good in vitro hypoglycemic and antioxidant activities and that these activities may be related to the fact that the SGP-1-1's monosaccharide composition (a higher proportion of Gal and Man) is the glycosidic-bond type (α- and ß-glycosidic bonds). SGP-1-1 could be used as a potential antioxidant and hypoglycemic candidate for functional and nutritional food applications.


Assuntos
Antioxidantes , Hipoglicemiantes , Antioxidantes/química , Antioxidantes/farmacologia , Humanos , Hipoglicemiantes/farmacologia , Peso Molecular , Monossacarídeos/análise , Polissacarídeos/química
16.
Sci Rep ; 12(1): 11305, 2022 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-35787637

RESUMO

We report Brownian dynamics simulation results with the specific goal to identify key parameters controlling the experimentally measurable characteristics of protein tags on a dsDNA construct translocating through a double nanopore setup. First, we validate the simulation scheme in silico by reproducing and explaining the physical origin of the asymmetric experimental dwell time distributions of the oligonucleotide flap markers on a 48 kbp long dsDNA at the left and the right pore. We study the effect of the electric field inside and beyond the pores, critical to discriminate the protein tags based on their effective charges and masses revealed through a generic power-law dependence of the average dwell time at each pore. The simulation protocols monitor piecewise dynamics at a sub-nanometer length scale and explain the disparate velocity using the concepts of nonequilibrium tension propagation theory. We further justify the model and the chosen simulation parameters by calculating the Péclet number which is in close agreement with the experiment. We demonstrate that our carefully chosen simulation strategies can serve as a powerful tool to discriminate different types of neutral and charged tags of different origins on a dsDNA construct in terms of their physical characteristics and can provide insights to increase both the efficiency and accuracy of an experimental dual-nanopore setup.


Assuntos
Nanoporos , DNA , Eletricidade , Simulação de Dinâmica Molecular , Peso Molecular
17.
Methods Mol Biol ; 2473: 259-284, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35819771

RESUMO

Light scattering methods permit the determination of molar mass and hydrodynamic radius for a protein from first principles. They are, therefore, particularly useful for the biophysical characterization of any protein. Molar mass and hydrodynamic radius determinations may be used to demonstrate that the protein of interest multimerizes. In the endomembrane system, reversible and regulated assembly and multimerization of proteins is critical for building coats required for vesicle budding, for the function of membrane remodeling machines, for fission and fusion and for assembling and disassembling trafficking intermediates. Light scattering methods have therefore significantly contributed to the understanding of the underlying trafficking processes. Herein, we describe methods to express and purify the recombinant fungal SNX-BAR Mvp1, a membrane remodeling protein required for retrograde trafficking at the endosome. Using Mvp1 as an example, we provide protocols for determining its molar mass and hydrodynamic radius by multiangle static light scattering and dynamic light scattering, respectively. These methods can be applied directly to the study of other membrane trafficking proteins, yielding a wealth of biophysical and biochemical information.


Assuntos
Hidrodinâmica , Proteínas , Endossomos , Membranas , Peso Molecular
18.
Artigo em Inglês | MEDLINE | ID: mdl-35805509

RESUMO

Peat-derived organic matter, as powerful chelators, is of great significance for the transport of Fe to the ocean and the enhancement of dissolved Fe. However, the iron binding capacity of molecular weight (MW)-fractionated dissolved organic matter is variable, due to its structure and composition heterogeneity. In this work, we used the standard Pahokee Peat fulvic acid (PPFA) as an example, and investigated the spectroscopy properties and Fe(III) binding ability of PPFA and different molecular weight fractions by UV-Vis absorbance and fluorescence spectroscopy and the Donnan Membrane Technique (DMT). The results showed binding sites for Fe(III) at the 263 nm and >320 nm regions in differential absorbance spectra. Upon increasing the iron concentration to 18.00 µmol·L-1, the critical binding capacity was exceeded, which resulted in a decrease in absorbance. Fe(III) was found to prefer to bind to humic-like components, and ultraviolet humic-like fluorophores displayed stronger binding strength. High molecular weight PPFA fractions (>10 kDa) possessed more aromatic and hydrophobic components, displayed a higher degree of humification, and exhibited higher metal binding potential. Furthermore, the speciation analysis and stability constant (cK) were calculated using Donnan membrane equilibrium. The correlation between cK values and PPFA spectral properties demonstrated that aromaticity, hydrophobicity, molecular weight and humification degree were crucial indices of PPFA-Fe(III) affinity. Significantly, the humification degree, represented by HIX, showed the strongest correlation (r = 0.929, p = 0.003), which could be used to estimate the binding strength. This study provides further understanding of the complexation mechanism of iron and DOM in the peat environment and identifies the considerable effect of molecular weight.


Assuntos
Substâncias Húmicas , Solo , Benzopiranos , Compostos Férricos , Substâncias Húmicas/análise , Ferro/química , Peso Molecular , Solo/química , Espectrometria de Fluorescência
19.
Molecules ; 27(14)2022 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-35889309

RESUMO

Polysaccharides were extracted from natural sources with various biological activities, which are strongly influenced by their chemical structure and molecular weight. In this research, mannans polysaccharides were obtained from Saccharomyces cerevisiae by ethanol precipitation. The molecular weight of YM50, YM70, and YM90 mannans was 172.90 kDa, 87.09 kDa, and 54.05 kDa, respectively. Scanning electron microscopy of YM 90 mannans showed a rough surface with numerous cavities, while the surfaces of YM50 and YM70 were relatively smooth. Sepharose CL-6B and FTIR indicated that mannans had the characteristic bands of polysaccharides. The antioxidant activities of polysaccharides were evaluated in vitro using various assays. Mannans showed a good scavenging activity of DPPH radicals which depend on the molecular weight and concentration, and a higher scavenging activity of hydroxyl radical than ferric-reducing power activities. For the three types of mannans, cytotoxicity and hemolytic activity were rarely detected in mice erythrocytes and Caco-2 cells. Those results could contribute to the further application of mannans from Saccharomyces cerevisiae in the food and medicine industry.


Assuntos
Antioxidantes , Mananas , Animais , Antioxidantes/química , Antioxidantes/farmacologia , Células CACO-2 , Humanos , Mananas/química , Mananas/farmacologia , Camundongos , Peso Molecular , Polissacarídeos/química , Saccharomyces cerevisiae
20.
Molecules ; 27(14)2022 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-35889391

RESUMO

Diarrhea-based Irritable Bowel Syndrome (D-IBS) and diarrhea are both associated with ecological imbalance of the gut microbiota. Low Molecular Weight Peptides (LMWP) from the larvae of Musca domestica have been shown to be effective in the treatment of diarrhea and regulation of gut microbiota. Meanwhile, the single polypeptide S3-3 was successfully isolated and identified from LMWP in our previous studies. It remains unclear exactly whether and how LMWP (S3-3) alleviate D-IBS through regulating gut microbiota. We evaluated the gut microbiota and pharmacology to determine the regulation of gut microbiota structure and the alleviating effect on D-IBS through LMWP (S3-3). The rates of loose stools, abdominal withdrawal reflex (AWR) and intestinal tract motility results revealed that LMWP (S3-3) from the larvae of Musca domestica had a regulating effect against diarrhea, visceral hypersensitivity and gastrointestinal (GI) dysfunction in D-IBS model mice. Additionally, 16S rRNA gene sequencing was utilized to examine the gut microbiota, which suggests that LMWP induce structural changes in the gut microbiota and alter the levels of the following gut microbiota: Bacteroidetes, Proteobacteria and Verrucomicrobia. LMWP putatively functioned through regulating 5-HT, SERT, 5-HT2AR, 5-HT3AR and 5-HT4R according to the results of ELISA, qRT-PCR and IHC. The findings of this study will contribute to further understanding how LMWP (S3-3) attenuate the effects of D-IBS on diarrhea, visceral hypersensitivity and GI dysfunction.


Assuntos
Microbioma Gastrointestinal , Moscas Domésticas , Síndrome do Intestino Irritável , Animais , Diarreia/tratamento farmacológico , Microbioma Gastrointestinal/fisiologia , Síndrome do Intestino Irritável/tratamento farmacológico , Larva , Camundongos , Peso Molecular , Peptídeos , RNA Ribossômico 16S/genética
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