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1.
Waste Manag ; 118: 647-654, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33011542

RESUMO

The elimination of rubber wastes without affecting the environment is one of the most important challenges of the 21st century waste management. Accordingly, the present work is focused on the recycling of natural rubber (NR) industry waste by means of devulcanization in supercritical carbon dioxide (scCO2) atmosphere. With that aim, a novel device allowing to perform rubber devulcanization was developed. It consists of a triaxial compression reactor integrated into a dynamic hydraulic universal testing machine with a heating chamber. NR industry waste was devulcanized in the mentioned device at different temperatures, in scCO2 by using diphenyl disulfide (DD) as devulcanizing reagent. The devulcanization degree and quality of the treated materials were evaluated by the swelling test combined with the Horikx theory. It was appeared that a successful devulcanization, with almost no degradation, was obtained, and the devulcanization degree reached maximum value of ~90%. Thermogravimetric tests and scanning electron microscopy (SEM) images strengthened these results. Finally, it was concluded that the developed device is appropriate to perform rubber recycling, which contributes to the progress in the environmental protection.


Assuntos
Resíduos Industriais , Borracha , Dióxido de Carbono , Dissulfetos , Reciclagem
2.
PLoS Biol ; 18(9): e3000821, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32886672

RESUMO

As a novel alternative to established surface display or combinatorial chemistry approaches for the discovery of therapeutic peptides, we present a method for the isolation of small, cysteine-rich domains from bovine antibody ultralong complementarity-determining regions (CDRs). We show for the first time that isolated bovine antibody knob domains can function as autonomous entities by binding antigen outside the confines of the antibody scaffold. This yields antibody fragments so small as to be considered peptides, each stabilised by an intricate, bespoke arrangement of disulphide bonds. For drug discovery, cow immunisations harness the immune system to generate knob domains with affinities in the picomolar to low nanomolar range, orders of magnitude higher than unoptimized peptides from naïve library screening. Using this approach, knob domain peptides that tightly bound Complement component C5 were obtained, at scale, using conventional antibody discovery and peptide purification techniques.


Assuntos
Anticorpos/química , Dissulfetos/isolamento & purificação , Domínios de Imunoglobulina , Fragmentos de Peptídeos/isolamento & purificação , Domínios e Motivos de Interação entre Proteínas , Animais , Anticorpos/imunologia , Anticorpos/metabolismo , Afinidade de Anticorpos , Formação de Anticorpos , Especificidade de Anticorpos , Antígenos/genética , Antígenos/imunologia , Linfócitos B/fisiologia , Bovinos , Complemento C5/química , Complemento C5/genética , Complemento C5/imunologia , Regiões Determinantes de Complementaridade/química , Regiões Determinantes de Complementaridade/genética , Regiões Determinantes de Complementaridade/imunologia , Dissulfetos/química , Dissulfetos/imunologia , Mapeamento de Epitopos/métodos , Humanos , Imunização , Domínios de Imunoglobulina/genética , Modelos Moleculares , Fragmentos de Peptídeos/genética , Fragmentos de Peptídeos/imunologia , Domínios e Motivos de Interação entre Proteínas/genética
3.
Nat Commun ; 11(1): 4512, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32908147

RESUMO

Hydrogen peroxide (H2O2) is recognized to act as a signaling molecule. Peroxiredoxins (Prxs) have the ability to transfer H2O2-derived oxidizing equivalents to redox-regulated target proteins, thus facilitating the transmission of H2O2 signals. It has remained unclear how Prxs and their target proteins are brought together to allow for target-specific protein thiol oxidation. Addressing the specific case of Prx2-dependent STAT3 oxidation, we here show that the association of the two proteins occurs prior to Prx oxidation and depends on a scaffolding protein, the membrane chaperone annexin A2. Deletion or depletion of annexin A2 interrupts the transfer of oxidizing equivalents from Prx2 to STAT3, which is observed to take place on membranes. These findings support the notion that the Prx2-STAT3 redox relay is part of a highly organized membrane signaling domain.


Assuntos
Anexina A2/metabolismo , Peroxirredoxinas/metabolismo , Fator de Transcrição STAT3/metabolismo , Anexina A2/genética , Linhagem Celular Tumoral , Membrana Celular/metabolismo , Dissulfetos/metabolismo , Células HEK293 , Humanos , Peróxido de Hidrogênio/metabolismo , Oxirredução , Ligação Proteica , Domínios Proteicos , Transdução de Sinais
4.
Yakugaku Zasshi ; 140(9): 1119-1128, 2020.
Artigo em Japonês | MEDLINE | ID: mdl-32879244

RESUMO

Humans are exposed to various xenobiotic electrophiles on a daily basis. Electrophiles form covalent adducts with nucleophilic residues of proteins. Redox signaling, which consists of effector molecules (e.g., kinases and transcription factors) and redox sensor proteins with low pKa cysteine residues, is involved in cell survival, cell proliferation, quality control of cellular proteins and oxidative stress response. Herein, we showed that at a low dose, xenobiotic electrophiles selectively modified redox sensor proteins through covalent modification of their reactive thiols, resulting in activation of a variety of redox signaling pathways. However, increasing the dose of xenobiotic electrophiles caused non-selective and extensive modification of cellular proteins involved in toxicity. Of interest, reactive sulfur species (RSS), such as hydrogen sulfide (H2S), cysteine persulfide (CysSSH), glutathione persulfide (GSSH) and even synthetic polysulfide (e.g., Na2S4), readily captured xenobiotic electrophiles, forming their sulfur adducts, which was associated with inactivation of the electrophiles. Our findings suggest that an adaptive response through redox signaling activation and RSS-mediated electrophile capturing is involved in the regulation of electrophilic stress.


Assuntos
Cisteína/análogos & derivados , Dissulfetos/metabolismo , Glutationa/análogos & derivados , Sulfeto de Hidrogênio/metabolismo , Oxirredução , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais , Animais , Cisteína/metabolismo , Glutationa/metabolismo , Humanos , Compostos de Sulfidrila/metabolismo , Xenobióticos/metabolismo
5.
Nat Commun ; 11(1): 4170, 2020 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-32820174

RESUMO

Sulfur-sulfur motifs widely occur in vital function and drug design, which yearns for polysulfide construction in an efficient manner. However, it is a great challenge to install desired functional groups on both sides of sulfur-sulfur bonds at liberty. Herein, we designed a mesocyclic bilateral disulfurating reagent for sequential assembly and modular installation of polysulfides. Based on S-O bond dissociation energy imparity (mesocyclic compared to linear imparity is at least 5.34 kcal mol-1 higher), diverse types of functional molecules can be bridged via sulfur-sulfur bonds distinctly. With these stable reagents, excellent reactivities with nucleophiles including C, N and S are comprehensively demonstrated, sequentially installing on both sides of sulfur-sulfur motif with various substituents to afford six species of unsymmetrical polysulfides including di-, tri- and even tetra-sulfides. Life-related molecules, natural products and pharmaceuticals can be successively cross-linked with sulfur-sulfur bond. Remarkably, the cyclization of tri- and tetra-peptides affords 15- and 18-membered cyclic disulfide peptides with this reagent, respectively.


Assuntos
Dissulfetos/química , Indicadores e Reagentes/química , Peptídeos/química , Sulfetos/química , Enxofre/química , Produtos Biológicos/química , Técnicas de Química Sintética/métodos , Ciclização , Indicadores e Reagentes/síntese química , Modelos Químicos , Estrutura Molecular , Oxirredução , Preparações Farmacêuticas/química
6.
Int J Nanomedicine ; 15: 5517-5526, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32801703

RESUMO

Introduction: Hypertension is a major health problem worldwide and is typically treated using oral drugs. However, the frequency of oral administration may result in poor patient compliance, and reduced bioavailability owing to the first-pass effect can also prove problematic. Methods: In this study, we developed a new transdermal-drug-delivery system (TDDS) for the treatment of hypertension using atenolol (ATE) based on poly(acrylic acid) (PAA)-decorated three-dimensional (3D) flower-like MoS2 nanoparticles (PAA-MoS2 NPs) that respond to NIR laser irradiation. The PAA-modified MoS2 NPs were synthesized and characterized using attenuated total reflection Fourier-transform infrared spectroscopy, X-ray diffraction measurements, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, and the sedimentation equilibrium method. The drug-loading efficiency and photothermal conversion effect were also explored. Results: The results showed that the colloidally stable PAA-MoS2 NPs exhibited a high drug-loading capacity of 54.99% and high photothermal conversion ability. Further, the capacity of the PAA-MoS2 NPs for controlled release was explored using in vitro drug-release and skin-penetration studies. The drug-release percentage was 44.72 ± 1.04%, and skin penetration was enhanced by a factor of 1.85 in the laser-stimulated group. Sustained and controlled release by the developed TDDS were observed with laser stimulation. Moreover, in vivo erythema index analysis verified that the PAA-MoS2 NPs did not cause skin irritation. Discussion: Our findings demonstrate that PAA-MoS2 NPs can be used as a new carrier for transdermal drug delivery for the first time.


Assuntos
Anti-Hipertensivos/administração & dosagem , Atenolol/administração & dosagem , Dissulfetos/química , Sistemas de Liberação de Medicamentos/métodos , Molibdênio/química , Nanopartículas/administração & dosagem , Resinas Acrílicas/química , Administração Cutânea , Animais , Anti-Hipertensivos/farmacocinética , Atenolol/efeitos adversos , Atenolol/farmacocinética , Sistemas de Liberação de Medicamentos/efeitos adversos , Liberação Controlada de Fármacos , Difusão Dinâmica da Luz , Eritema/induzido quimicamente , Humanos , Lasers , Masculino , Microscopia Eletrônica de Transmissão , Nanopartículas/química , Coelhos , Ratos Wistar , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
7.
PLoS One ; 15(8): e0237884, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32841243

RESUMO

The Solanum tuberosum plant specific insert (StPSI) has a defensive role in potato plants, with the requirements of acidic pH and anionic lipids. The StPSI contains a set of three highly conserved disulfide bonds that bridge the protein's helical domains. Removal of these bonds leads to enhanced membrane interactions. This work examined the effects of their sequential removal, both individually and in combination, using all-atom molecular dynamics to elucidate the role of disulfide linkages in maintaining overall protein tertiary structure. The tertiary structure was found to remain stable at both acidic (active) and neutral (inactive) pH despite the removal of disulfide linkages. The findings include how the dimer structure is stabilized and the impact on secondary structure on a residue-basis as a function of disulfide bond removal. The StPSI possesses an extensive network of inter-monomer hydrophobic interactions and intra-monomer hydrogen bonds, which is likely the key to the stability of the StPSI by stabilizing local secondary structure and the tertiary saposin-fold, leading to a robust association between monomers, regardless of the disulfide bond state. Removal of disulfide bonds did not significantly impact secondary structure, nor lead to quaternary structural changes. Instead, disulfide bond removal induces regions of amino acids with relatively higher or lower variation in secondary structure, relative to when all the disulfide bonds are intact. Although disulfide bonds are not required to preserve overall secondary structure, they may have an important role in maintaining a less plastic structure within plant cells in order to regulate membrane affinity or targeting.


Assuntos
Dissulfetos/metabolismo , Simulação de Dinâmica Molecular , Proteínas de Plantas/metabolismo , Saposinas/metabolismo , Solanum tuberosum/metabolismo , Cisteína/metabolismo , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Proteínas de Plantas/química , Multimerização Proteica , Estabilidade Proteica , Estrutura Secundária de Proteína , Sais/química , Enxofre/metabolismo
8.
Sci Total Environ ; 742: 140545, 2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-32629262

RESUMO

Despite growing applications of molybdenum(IV) sulfide (MoS2) nano- and microparticles in their capacity as lubricants, data available on their safety are scarce. In this study the effect of MoS2 nano- and microparticles after single intratracheal instillation in rats has been analyzed. MoS2 suspensions were administered at the dose of 1.5 or 5 mg MoS2/kg body weight. The analysis after 24 h and 7 days included: blood biochemical parameters, hematological parameters, bronchoalveolar lavage fluid (BALF) parameters with selected cytokines, a comet assay and histopathological examination. In the BALF cells isolated from animals exposed to both forms, numerous macrophages loaded with particles were observed. The hematological and biochemical parameters analyzed 24 h or 7 days after the exposure to both forms did not show any biologically meaningful changes. Comet assay results showed no genotoxic effect. The histopathological analysis of the lungs revealed inflammatory changes in the respiratory system of the treated animals, slightly stronger for the microsized form. The deposits of particles observed in the lung tissue up to 7 days after the instillation indicate their easy penetration through the epithelium and prolonged clearance. Concluding, no meaningful acute systemic effects were observed, however some pathological changes were noted in the lung tissue.


Assuntos
Pulmão , Molibdênio , Animais , Líquido da Lavagem Broncoalveolar , Dissulfetos , Contagem de Leucócitos , Ratos
9.
PLoS One ; 15(6): e0234901, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32579565

RESUMO

Lasso peptides are unique in that the tail of the lasso peptide threads through its macrolactam ring. The unusual structure and biological activity of lasso peptides have generated increased interest from the scientific community in recent years. Because of this, many new types of lasso peptides have been discovered. These peptides can be synthesized by microorganisms efficiently, and yet, their chemical assembly is challenging. Herein, we investigated the possibility of high pressure inducing the cyclization of linear precursors of lasso peptides. Unlike other molecules like rotaxanes which mechanically interlock at high pressure, the threaded lasso peptides did not form, even at pressures the high pressure up to 14 000 kbar.


Assuntos
Peptídeos/química , Peptídeos/síntese química , Sequência de Aminoácidos , Ciclização , Dissulfetos/química , Oxirredução , Pressão , Conformação Proteica , Soluções
10.
Food Chem ; 330: 127319, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32569936

RESUMO

The influence of fresh egg white (EW) addition on the quality characteristics and protein aggregation in oat noodles containing wheat flour and gluten was studied. EW addition decreased cooking loss and increased cooking time of 70% oat noodles. The hardness, chewiness, tensile force and tensile distance improved significantly. A smooth surface and continuous protein network were observed by scanning electron microscopy (SEM) after adding EW. After cooking, the peak area in SE-HPLC profile of 70% oat noodles with EW decreased obviously. The extractabilities of protein in sodium dodecyl sulfate containing medium (SDSEP) of cooked wheat and oat noodles under non-reducing condition were lower than those of samples under reducing condition. The protein bands changes in SDS-PAGE profiles showed that EW could induce disulfide cross-linking of proteins in noodles. EW addition promoted proteins interaction and improved the cooking and texture properties of oat noodles.


Assuntos
Avena , Clara de Ovo/química , Farinha , Qualidade dos Alimentos , Cromatografia em Gel , Cromatografia Líquida de Alta Pressão , Culinária , Dissulfetos/química , Eletroforese em Gel de Poliacrilamida , Farinha/análise , Indústria de Processamento de Alimentos , Glutens , Dureza , Microscopia Eletrônica de Varredura , Agregados Proteicos , Triticum
11.
Nat Commun ; 11(1): 3219, 2020 06 26.
Artigo em Inglês | MEDLINE | ID: mdl-32591542

RESUMO

The receptor-linked protein tyrosine phosphatases (RPTPs) are key regulators of cell-cell communication through the control of cellular phosphotyrosine levels. Most human RPTPs possess an extracellular receptor domain and tandem intracellular phosphatase domains: comprising an active membrane proximal (D1) domain and an inactive distal (D2) pseudophosphatase domain. Here we demonstrate that PTPRU is unique amongst the RPTPs in possessing two pseudophosphatase domains. The PTPRU-D1 displays no detectable catalytic activity against a range of phosphorylated substrates and we show that this is due to multiple structural rearrangements that destabilise the active site pocket and block the catalytic cysteine. Upon oxidation, this cysteine forms an intramolecular disulphide bond with a vicinal "backdoor" cysteine, a process thought to reversibly inactivate related phosphatases. Importantly, despite the absence of catalytic activity, PTPRU binds substrates of related phosphatases strongly suggesting that this pseudophosphatase functions in tyrosine phosphorylation by competing with active phosphatases for the binding of substrates.


Assuntos
Proteínas Tirosina Fosfatases Classe 2 Semelhantes a Receptores/metabolismo , Motivos de Aminoácidos , Sequência de Aminoácidos , Biocatálise , Linhagem Celular , Dissulfetos/metabolismo , Estabilidade Enzimática , Humanos , Modelos Moleculares , Oxirredução , Ligação Proteica , Domínios Proteicos , Proteínas Tirosina Fosfatases Classe 2 Semelhantes a Receptores/química , Especificidade por Substrato
12.
Food Chem ; 329: 127196, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32516712

RESUMO

Pigeon pea is rich in proteins but has low protein digestibility like other legumes. This work investigated the effects of processing, including soaking, grinding, ultrasound and microwave, on the protein digestibility of pigeon pea flour. Only microwave treatment significantly increased in vitro protein digestibility from 54.4 ± 2.5% to 71.6 ± 4.2%. SDS-PAGE showed that the most abundant proteins in all samples were the 7S vicilin subunits. After microwave treatment, the starch granular structures of pigeon pea flour changed to clusters, and protein secondary structures lost 5% ß-sheet and gained 5% random coil, which contributed to the increased protein digestibility. Microwave decreased protein water solubility from 94.4 ± 0.8% to 48.1 ± 6.5% and increased the disulfide bond content by 42%. The increased protein digestibility is attributable to the relatively reduced particle size (166.6 ± 38.6 nm) and increased zeta potential (-35.2 ± 2.6 mV) of the microwave-treated sample. Therefore, microwave is a promising approach for increasing pigeon pea flour protein quality and utilisation.


Assuntos
Cajanus/metabolismo , Farinha/análise , Micro-Ondas , Proteínas de Plantas/metabolismo , Animais , Dissulfetos/química , Hidrólise , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Proteínas de Plantas/química , Estrutura Secundária de Proteína , Proteínas de Armazenamento de Sementes/química , Proteínas de Armazenamento de Sementes/metabolismo , Solubilidade , Amido/química
13.
Proteins ; 88(11): 1387-1393, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32543705

RESUMO

Coronavirus disease 2019 (COVID-19) is a pandemic infectious disease caused by novel severe acute respiratory syndrome coronavirus-2 (SARS CoV-2). The SARS CoV-2 is transmitted more rapidly and readily than SARS CoV. Both, SARS CoV and SARS CoV-2 via their glycosylated spike proteins recognize the human angiotensin converting enzyme-2 (ACE-2) receptor. We generated multiple sequence alignments and phylogenetic trees for representative spike proteins of SARS CoV and SARS CoV-2 from various host sources in order to analyze the specificity in SARS CoV-2 spike proteins required for causing infection in humans. Our results show that among the genomes analyzed, two sequence regions in the N-terminal domain "MESEFR" and "SYLTPG" are specific to human SARS CoV-2. In the receptor-binding domain, two sequence regions "VGGNY" and "EIYQAGSTPCNGV" and a disulfide bridge connecting 480C and 488C in the extended loop are structural determinants for the recognition of human ACE-2 receptor. The complete genome analysis of representative SARS CoVs from bat, civet, human host sources, and human SARS CoV-2 identified the bat genome (GenBank code: MN996532.1) as closest to the recent novel human SARS CoV-2 genomes. The bat SARS CoV genomes (GenBank codes: MG772933 and MG772934) are evolutionary intermediates in the mutagenesis progression toward becoming human SARS CoV-2.


Assuntos
Betacoronavirus/química , Interações Hospedeiro-Patógeno/fisiologia , Peptidil Dipeptidase A/metabolismo , Glicoproteína da Espícula de Coronavírus/química , Animais , Betacoronavirus/genética , Betacoronavirus/metabolismo , Sítios de Ligação , Quirópteros/virologia , Dissulfetos/química , Evolução Molecular , Humanos , Filogenia , Alinhamento de Sequência , Glicoproteína da Espícula de Coronavírus/metabolismo
14.
Int J Nanomedicine ; 15: 2971-2986, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32431496

RESUMO

Background: Due to their extraordinary physical and chemical properties, MoS2 nanosheets (MSNs) are becoming more widely used in nanomedicine. However, their influence on immune systems remains unclear. Materials and Methods: Two few-layered MSNs at sizes of 100-250 nm (S-MSNs) and 400-500 nm (L-MSNs) were used in this study. Bone marrow-derived dendritic cells (DCs) were exposed to both MSNs at different doses (0, 8, 16, 32, 64, 128 µg/mL) for 48 h and subjected to analyses of surface marker expression, cytokine secretion, lymphoid homing and in vivo T cell priming. Results: Different-sized MSNs of all doses did not affect the viability of DCs. The expression of CD40, CD80, CD86 and CCR7 was significantly higher on both S-MSN- and L-MSN-treated DCs at a dose of 128 µg/mL. As the dose of MSN increased, the secretion of IL-12p70 remained unchanged, the secretion of IL-1ß decreased, and the production of TNF-α increased. A significant increase in IL-6 was observed in the 128 µg/mL L-MSN-treated DCs. In particular, MSN treatment dramatically improved the ex vivo movement and in vivo homing ability of both the local resident and blood circulating DCs. Furthermore, the cytoskeleton rearrangement regulated by ROS elevation was responsible for the enhanced homing ability of the MSNs. More robust CD4+ and CD8+ T cell proliferation and activation (characterized by high expression of CD107a, CD69 and ICOS) was observed in mice vaccinated with MSN-treated DCs. Importantly, exposure to MSNs did not interrupt LPS-induced DC activation, homing and T cell priming. Conclusion: Few-layered MSNs ranging from 100 to 500 nm in size could play an immunostimulatory role in enhancing DC maturation, migration and T cell elicitation, making them a good candidate for vaccine adjuvants. Investigation of this study will not only expand the applications of MSNs and other new transition metal dichalcogenides (TMDCs) but also shed light on the in vivo immune-risk evaluation of MSN-based nanomaterials.


Assuntos
Diferenciação Celular , Movimento Celular , Células Dendríticas/citologia , Células Dendríticas/imunologia , Dissulfetos/farmacologia , Molibdênio/farmacologia , Nanopartículas/química , Linfócitos T/citologia , Linfócitos T/imunologia , Animais , Diferenciação Celular/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Citoesqueleto/efeitos dos fármacos , Citoesqueleto/metabolismo , Células Dendríticas/efeitos dos fármacos , Lipopolissacarídeos/farmacologia , Masculino , Camundongos Endogâmicos C57BL , Nanopartículas/ultraestrutura , Espécies Reativas de Oxigênio/metabolismo , Linfócitos T/efeitos dos fármacos
15.
Chemosphere ; 255: 126995, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32416394

RESUMO

In this paper, we present the preparation of MoS2-modified magnetic biochar (MoS2@MBC) as a novel adsorbent by a simple hydrothermal method. MoS2@MBC contains abundant S-containing functional groups that facilitate efficient Cd(II) removal from aqueous systems. We employed various characterization techniques to explore the morphology, surface area, and chemical composition of MoS2@MBC; these included Brunauer-Emmett-Teller analysis scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction,. The results indicated the successful decoration of the surface of MoS2@MBC with iron and MoS2, and a higher surface area of MoS2@MBC than that of unmodified biochar. Moreover, adsorption properties including thermodynamics and kinetics were investigated along with the effects of pH, humic acid, and ionic strength on the Cd(II) adsorption onto MoS2@MBC. The O-, C-, S-, and Fe-containing functional groups on the surface of MoS2@MBC led to an electrostatic attraction of Cd(II) and strong Cd-S complexation. The Langmuir and pseudo second-order models fitted best for the batch adsorption experiments results. The adsorption capacity of MoS2@MBC (139 mg g-1 on the basis of the Langmuir model) was 7.81 times higher than that of pristine biochar. The adsorption process was found to be pH-dependent. The experimental results indicated that MoS2@MBC is an effective adsorbent for removing Cd(II) from water solutions. Further, the adsorption process involved the complexation of Cd(II) with oxygen-based functional groups, ion exchange, electrostatic attraction, Cd(II)-π interactions, metal-sulfur complexation, and inner-surface complexation. This work provides new insights into the Cd(II) ions removal from water via adsorption. It also demonstrates that MoS2@MBC is an efficient and economic adsorbent to treat Cd(II)-contaminated water.


Assuntos
Adsorção , Cádmio/isolamento & purificação , Carvão Vegetal/química , Dissulfetos/química , Molibdênio/química , Purificação da Água/métodos , Cádmio/química , Cinética , Concentração Osmolar , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
16.
Food Chem ; 327: 127048, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32454285

RESUMO

In our previous study, a novel LMW-GS designated as LMW-N13 with a unique molecular structure was identified from Aegilops uniaristata. LMW-N13 has been characterized as the largest LMW-GS, so far, and possesses an extra cysteine residue compared with typical LMW-GS. In order to analyze the contribution of LMW-N13 to dough quality, in this work, three transgenic wheat lines overexpressing LMW-N13 were generated. Compared with non-transformation (NT) lines, transgenic (TG) lines demonstrated superior dough properties. These superior dough properties were accompanied by the higher contents of glutenin macropolymer (GMP) and total protein. The microstructure of the dough was further investigated by scanning electron microscopy; starch granules in NT lines were smaller than those in transgenic lines. The protein matrix in NT lines was relatively loose and discontinuous. Conversely, the protein matrix in transgenic lines was more continuous and tight. The application of LMW-N13 in wheat breeding is also discussed.


Assuntos
Farinha/análise , Glutens/química , Plantas Geneticamente Modificadas/química , Triticum/química , Aegilops/genética , Dissulfetos/química , Glutens/genética , Glutens/metabolismo , Microscopia Eletrônica de Varredura , Peso Molecular , Plantas Geneticamente Modificadas/metabolismo , Amido/química , Triticum/metabolismo , Água/química
17.
Proc Natl Acad Sci U S A ; 117(21): 11450-11458, 2020 05 26.
Artigo em Inglês | MEDLINE | ID: mdl-32385162

RESUMO

Dynamic remodeling of the extracellular matrix affects many cellular processes, either directly or indirectly, through the regulation of soluble ligands; however, the mechanistic details of this process remain largely unknown. Here we propose that type I collagen remodeling regulates the receptor-binding activity of pigment epithelium-derived factor (PEDF), a widely expressed secreted glycoprotein that has multiple important biological functions in tissue and organ homeostasis. We determined the crystal structure of PEDF in complex with a disulfide cross-linked heterotrimeric collagen peptide, in which the α(I) chain segments-each containing the respective PEDF-binding region (residues 930 to 938)-are assembled with an α2α1α1 staggered configuration. The complex structure revealed that PEDF specifically interacts with a unique amphiphilic sequence, KGHRGFSGL, of the type I collagen α1 chain, with its proposed receptor-binding sites buried extensively. Molecular docking demonstrated that the PEDF-binding surface of type I collagen contains the cross-link-susceptible Lys930 residue of the α1 chain and provides a good foothold for stable docking with the α1(I) N-telopeptide of an adjacent triple helix in the fibril. Therefore, the binding surface is completely inaccessible if intermolecular crosslinking between two crosslink-susceptible lysyl residues, Lys9 in the N-telopeptide and Lys930, is present. These structural analyses demonstrate that PEDF molecules, once sequestered around newly synthesized pericellular collagen fibrils, are gradually liberated as collagen crosslinking increases, making them accessible for interaction with their target cell surface receptors in a spatiotemporally regulated manner.


Assuntos
Colágeno Tipo I/metabolismo , Proteínas do Olho/química , Proteínas do Olho/metabolismo , Fatores de Crescimento Neural/química , Fatores de Crescimento Neural/metabolismo , Serpinas/química , Serpinas/metabolismo , Sítios de Ligação , Dicroísmo Circular , Colágeno Tipo I/química , Cristalografia por Raios X , Dissulfetos/química , Lisina/química , Simulação de Acoplamento Molecular , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/metabolismo , Conformação Proteica , Transdução de Sinais , Análise Espaço-Temporal
18.
Proc Natl Acad Sci U S A ; 117(21): 11399-11408, 2020 05 26.
Artigo em Inglês | MEDLINE | ID: mdl-32398368

RESUMO

Spiders are one of the most successful venomous animals, with more than 48,000 described species. Most spider venoms are dominated by cysteine-rich peptides with a diverse range of pharmacological activities. Some spider venoms contain thousands of unique peptides, but little is known about the mechanisms used to generate such complex chemical arsenals. We used an integrated transcriptomic, proteomic, and structural biology approach to demonstrate that the lethal Australian funnel-web spider produces 33 superfamilies of venom peptides and proteins. Twenty-six of the 33 superfamilies are disulfide-rich peptides, and we show that 15 of these are knottins that contribute >90% of the venom proteome. NMR analyses revealed that most of these disulfide-rich peptides are structurally related and range in complexity from simple to highly elaborated knottin domains, as well as double-knot toxins, that likely evolved from a single ancestral toxin gene.


Assuntos
Proteínas de Artrópodes/química , Proteínas de Artrópodes/genética , Venenos de Aranha/química , Animais , Proteínas de Artrópodes/análise , Austrália , Dípteros/efeitos dos fármacos , Dissulfetos , Evolução Molecular , Feminino , Perfilação da Expressão Gênica , Espectrometria de Massas , Peptídeos/análise , Peptídeos/química , Peptídeos/genética , Filogenia , Conformação Proteica , Proteômica/métodos , Venenos de Aranha/genética , Venenos de Aranha/toxicidade , Aranhas/genética
19.
Food Chem ; 327: 127107, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32454281

RESUMO

Herein, we proposed a duplex and homogeneous fluorescent immunoassay for the simultaneous detection of amantadine (AMD) and chloramphenicol (CAP) residue in chicken breast with both high sensitivity and short assay time. The immunoassay was based on the fluorescence resonance energy transfer (FRET) between hapten-labeled carbon dots (CDs) and antibody-modified WS2 nanosheets. To achieve the duplex FRET, polyethyleneimine-functionalized blue and green emissive CDs with separated emission were synthesized via a one-pot hydrothermal method and directly coupled with the haptens of AMD and CAP, serving as the energy donors. The antibodies were modified on the surface of WS2 nanosheets with high quenching efficiency to construct the energy acceptor. The specific immunoreaction could trigger the efficient FRET between the donors and the acceptors, causing the fluorescence quenching of CDs. The developed immunoassay was applied to simultaneously detect AMD and CAP, having the detection limit of 0.10 ng g-1 and 0.06 ng g-1, respectively.


Assuntos
Amantadina/análise , Cloranfenicol/análise , Transferência Ressonante de Energia de Fluorescência , Imunoensaio , Carbono/química , Dissulfetos/química , Limite de Detecção , Nanoestruturas , Tungstênio/química
20.
Nat Commun ; 11(1): 2264, 2020 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-32385283

RESUMO

ABCG2 is an ABC transporter that extrudes a variety of compounds from cells, and presents an obstacle in treating chemotherapy-resistant cancers. Despite recent structural insights, no anticancer drug bound to ABCG2 has been resolved, and the mechanisms of multidrug transport remain obscure. Such a gap of knowledge limits the development of novel compounds that block or evade this critical molecular pump. Here we present single-particle cryo-EM studies of ABCG2 in the apo state, and bound to the three structurally distinct chemotherapeutics. Without the binding of conformation-selective antibody fragments or inhibitors, the resting ABCG2 adopts a closed conformation. Our cryo-EM, biochemical, and functional analyses reveal the binding mode of three chemotherapeutic compounds, demonstrate how these molecules open the closed conformation of the transporter, and establish that imatinib is particularly effective in stabilizing the inward facing conformation of ABCG2. Together these studies reveal the previously unrecognized conformational cycle of ABCG2.


Assuntos
Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Antineoplásicos/metabolismo , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/química , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/ultraestrutura , Antineoplásicos/química , Transporte Biológico , Dissulfetos/metabolismo , Células HEK293 , Humanos , Mesilato de Imatinib/metabolismo , Ligantes , Mitoxantrona/química , Mitoxantrona/metabolismo , Modelos Biológicos , Estrutura Secundária de Proteína
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