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1.
Molecules ; 26(4)2021 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-33562280

RESUMO

Oxidative protein folding is a biological process to obtain a native conformation of a protein through disulfide-bond formation between cysteine residues. In a cell, disulfide-catalysts such as protein disulfide isomerase promote the oxidative protein folding. Inspired by the active sites of the disulfide-catalysts, synthetic redox-active thiol compounds have been developed, which have shown significant promotion of the folding processes. In our previous study, coupling effects of a thiol group and guanidyl unit on the folding promotion were reported. Herein, we investigated the influences of a spacer between the thiol group and guanidyl unit. A conjugate between thiol and guanidyl units with a diethylene glycol spacer (GdnDEG-SH) showed lower folding promotion effect compared to the thiol-guanidyl conjugate without the spacer (GdnSH). Lower acidity and a more reductive property of the thiol group of GdnDEG-SH compared to those of GdnSH likely resulted in the reduced efficiency of the folding promotion. Thus, the spacer between the thiol and guanidyl groups is critical for the promotion of oxidative protein folding.


Assuntos
Etilenoglicol/química , Estresse Oxidativo/efeitos dos fármacos , Isomerases de Dissulfetos de Proteínas/química , Compostos de Sulfidrila/química , Catálise , Cisteína/química , Dissulfetos/química , Etilenoglicol/farmacologia , Glutationa/química , Cinética , Oxirredução/efeitos dos fármacos , Dobramento de Proteína/efeitos dos fármacos , Compostos de Sulfidrila/farmacologia
2.
Int J Mol Sci ; 21(24)2020 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-33327660

RESUMO

Self-assembled peptide nanofibers (NFs) obtained from ß-sheet peptides conjugated with drugs, including antigenic peptides, have recently attracted significant attention. However, extensive studies on the interactions of ß-sheet peptide NFs with model cell membranes have not been reported. In this study, we investigated the interactions between three types of NFs, composed of PEG-peptide conjugates with different ethylene glycol (EG) lengths (6-, 12- and 24-mer), and dipalmitoylphosphatidylcholine (DPPC) Langmuir membranes. When increasing the EG chain length, those interactions significantly decreased considering measurements in the presence of the NFs of: (i) changes in surface pressure of the DPPC Langmuir monolayers and (ii) surface pressure-area (π-A) compression isotherms of DPPC. Because the observed trend was similar to the EG length dependency with regard to cellular association and cytotoxicity of the NFs that was reported previously, the interaction of NFs with phospholipid membranes represented a crucial factor to determine the cellular association and toxicity of the NFs. In contrast to NFs, no changes were observed with varying EG chain length on the interaction of the building block peptide with the DPPC membrane. The results obtained herein can provide a design guideline on the formulation of ß-sheet peptide NFs, which may broaden its potential.


Assuntos
Membranas Artificiais , Nanofibras/química , Etilenoglicol/química
3.
Nat Commun ; 11(1): 721, 2020 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-32024848

RESUMO

Myo-inositol hexakisphosphate (IP6) is a natural product known to inhibit vascular calcification (VC), but with limited potency and low plasma exposure following bolus administration. Here we report the design of a series of inositol phosphate analogs as crystallization inhibitors, among which 4,6-di-O-(methoxy-diethyleneglycol)-myo-inositol-1,2,3,5-tetrakis(phosphate), (OEG2)2-IP4, displays increased in vitro activity, as well as more favorable pharmacokinetic and safety profiles than IP6 after subcutaneous injection. (OEG2)2-IP4 potently stabilizes calciprotein particle (CPP) growth, consistently demonstrates low micromolar activity in different in vitro models of VC (i.e., human serum, primary cell cultures, and tissue explants), and largely abolishes the development of VC in rodent models, while not causing toxicity related to serum calcium chelation. The data suggest a mechanism of action independent of the etiology of VC, whereby (OEG2)2-IP4 disrupts the nucleation and growth of pathological calcification.


Assuntos
Fosfatos de Inositol/química , Fosfatos de Inositol/farmacologia , Calcificação Vascular/tratamento farmacológico , 6-Fitase/metabolismo , Adenina/efeitos adversos , Animais , Células Cultivadas , Avaliação Pré-Clínica de Medicamentos/métodos , Difusão Dinâmica da Luz , Etilenoglicol/química , Humanos , Injeções Subcutâneas , Fosfatos de Inositol/farmacocinética , Masculino , Músculo Liso Vascular/citologia , Músculo Liso Vascular/efeitos dos fármacos , Ratos Sprague-Dawley , Uremia/tratamento farmacológico , Uremia/fisiopatologia , Calcificação Vascular/induzido quimicamente , Difração de Raios X
4.
Molecules ; 25(3)2020 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-31973133

RESUMO

Nanoceria (cerium oxide nanoparticles) have been shown to protect human lens epithelial cells (HLECs) from oxidative stress when used at low concentrations. However, there is a lack of understanding about the mechanism of the cytotoxic and genotoxic effects of nanoceria when used at higher concentrations. Here, we investigated the impact of 24-hour exposure to nanoceria in HLECs. Nanoceria's effects on basal reactive oxygen species (ROS), mitochondrial morphology, membrane potential, ATP, genotoxicity, caspase activation and apoptotic hallmarks were investigated. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) studies on isolated mitochondria revealed significant uptake and localization of nanoceria in the mitochondria. At high nanoceria concentrations (400 µg mL-1), intracellular levels of ROS were increased and the HLECs exhibited classical hallmarks of apoptosis. These findings concur with the cells maintaining normal ATP levels necessary to execute the apoptotic process. These results highlight the need for nanoceria dose-effect studies on a range of cells and tissues to identify therapeutic concentrations in vitro or in vivo.


Assuntos
Apoptose/efeitos dos fármacos , Cério/toxicidade , Epitélio/patologia , Cristalino/efeitos dos fármacos , Cristalino/patologia , Nanopartículas/toxicidade , Espécies Reativas de Oxigênio/metabolismo , Trifosfato de Adenosina/biossíntese , Caspase 3/metabolismo , Caspase 7/metabolismo , Dano ao DNA , Células Epiteliais/efeitos dos fármacos , Epitélio/efeitos dos fármacos , Etilenoglicol/química , Humanos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/ultraestrutura , Mutagênicos/toxicidade , Nanopartículas/ultraestrutura
5.
Biochim Biophys Acta Biomembr ; 1862(5): 183197, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-31958435

RESUMO

The bilayer phase transitions of medium-chain phosphatidylcholines with linear saturated acyl chains (Cn = 12, 13 and 14) were measured by high-pressure light-transmittance measurements and differential scanning calorimetry to investigate the formation of intermediate gel-liquid crystalline phase called Lx phase. The constructed phase diagrams showed that there existed a distinct region of the Lx phase between ripple gel (Pß') and liquid crystalline (Lα) phase for multilamellar vesicle bilayers of C12PC and C13PC. The Lx phase of the C12PC bilayer was metastable at all pressures and disappeared at a higher pressure. In the C13PC bilayer, the Lx phase was stable and also disappeared at a higher pressure but its region markedly shrunk. By contrast, the Lx phase was not detected for the C14PC bilayer. Effects of other factors such as vesicle size and solvent substitution on the Lx phase of the C13PC bilayer were also examined. A decrease in vesicle size and solvent substitution from water to 50 wt% ethylene glycol solution promoted the Lx-phase formation as opposed to the effects of acyl-chain elongation and pressurization. The fluorescence data of the C13PC bilayer with different vesicle sizes showed that the Lx phase is caused by the difference of local packing in the bilayer. Considering these facts, we concluded that the Lx phase is an intermediate gel-Lα phase that has gel-phase monolayers with negative curvature and Lα-phase monolayers with positive curvature. The formation mechanism of the Lx-phase in stacked bilayers and dispersed vesicles is also explainable by this difference in packing state.


Assuntos
Bicamadas Lipídicas/química , Fosfatidilcolinas/química , Varredura Diferencial de Calorimetria , Etilenoglicol/química , Lecitinas/química , Transição de Fase , Pressão , Temperatura , Termodinâmica , Água/química
6.
Curr Pharm Biotechnol ; 21(8): 741-747, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31793420

RESUMO

BACKGROUND: Although the stability of proteins is of significance to maintain protein function for therapeutical applications, this remains a challenge. Herein, a general method of preserving protein stability and function was developed using gelatin films. METHODS: Enzymes immobilized onto films composed of gelatin and Ethylene Glycol (EG) were developed to study their ability to stabilize proteins. As a model functional protein, ß-glucosidase was selected. The tensile properties, microstructure, and crystallization behavior of the gelatin films were assessed. RESULTS: Our results indicated that film configurations can preserve the activity of ß-glucosidase under rigorous conditions (75% relative humidity and 37°C for 47 days). In both control films and films containing 1.8 % ß-glucosidase, tensile strength increased with increased EG content, whilst the elongation at break increased initially, then decreased over time. The presence of ß-glucosidase had a negligible influence on tensile strength and elongation at break. Scanning electron-microscopy (SEM) revealed that with increasing EG content or decreasing enzyme concentrations, a denser microstructure was observed. CONCLUSION: In conclusion, the dry film is a promising candidate to maintain protein stabilization and handling. The configuration is convenient and cheap, and thus applicable to protein storage and transportation processes in the future.


Assuntos
Enzimas Imobilizadas/química , Etilenoglicol/química , Gelatina/química , beta-Glucosidase/química , Enzimas Imobilizadas/metabolismo , Gelatina/ultraestrutura , Umidade , Microscopia Eletrônica de Varredura , Estabilidade Proteica , Resistência à Tração , Difração de Raios X , beta-Glucosidase/metabolismo
7.
J Chromatogr A ; 1612: 460653, 2020 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-31706581

RESUMO

We introduce an integrated chip-approach for a postcolumn segmentation of normal phase liquid chromatography. This is achieved by the seamless integration of a chiral NP-chip-HPLC column, a flow-focusing droplet generator, and a segmented flow channel in a single microfluidic glass chip. This allows a continuous segmentation of the eluent into droplets which are picked up and transported via an immiscible continuous phase. The combination of NP-chip-HPLC and droplet microfluidics enables to fractionate and conserve chromatographic runs for further downstream processes at picoliter scale. An essential aspect is the proper choice of the continuous phase concerning polarity, wetting properties and viscosity. For this purpose, ethylene glycol is introduced which facilitates this first combination of normal phase chromatography and droplet microfluidics. By adjusting the flow rates and varying the generator geometry, the size and frequency of the droplets could be precisely controlled.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Etilenoglicol/química , Heptanos/química , Dispositivos Lab-On-A-Chip , Microfluídica/instrumentação , Microfluídica/métodos , Viscosidade
8.
ACS Appl Mater Interfaces ; 12(1): 238-249, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31820639

RESUMO

Utilizing protein chemistry in organic solvents has important biotechnology applications. Typically, organic solvents negatively impact protein structure and function. Immobilizing proteins via cross-links to a support matrix or to other proteins is a common strategy to preserve the native protein function. Recently, we developed methods to fabricate macroscopic responsive pure protein hydrogels by lightly cross-linking the proteins with glutaraldehyde for chemical sensing and enzymatic catalysis applications. The water in the resulting protein hydrogel can be exchanged for organic solvents. The resulting organogel contains pure organic solvents as their mobile phases. The organogel proteins retain much of their native protein function, i.e., protein-ligand binding and enzymatic activity. A stepwise ethylene glycol (EG) solvent exchange was performed to transform these hydrogels into organogels with a very low vapor pressure mobile phase. These responsive organogels are not limited by solvent/mobile phase evaporation. The solvent exchange to pure EG is accompanied by a volume phase transition (VPT) that decreases the organogel volume compared to that of the hydrogel. Our organogel sensor systems utilize shifts in the particle spacing of an attached two-dimensional photonic crystal (2DPC) to report on the volume changes induced by protein-ligand binding. Our 2DPC bovine serum albumin (BSA) organogels exhibit VPT that swell the organogels in response to the BSA binding of charged ligands like ibuprofen and fatty acids. To our knowledge, this is the first report of a pure protein organogel VPT induced by protein-ligand binding. Catalytic protein organogels were also fabricated that utilize the enzyme organophosphorus hydrolase (OPH) to hydrolyze toxic organophosphate (OP) nerve agents. Our OPH organogels retain significant enzymatic activity. The OPH organogel rate of OP hydrolysis is ∼160 times higher than that of un-cross-linked OPH monomers in a 1:1 ethylene glycol/water mixture.


Assuntos
Biocatálise , Etilenoglicol/química , Soroalbumina Bovina/química
9.
Magn Reson Chem ; 58(2): 163-169, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31671221

RESUMO

The chemical shift difference, Δσ, between the methylene and hydroxyl protons in the high resolution 1 H nuclear magnetic resonance spectrum of ethylene glycol is shown to be pressure dependent. The equilibrium Δσ values for ethylene glycol are reported as a function of temperature and pressure between ambient conditions, 323 K and 2 kbar, respectively. This surface is used along with Δσ values measured in response to a rapid pressure increase to calculate a temperature rise that is used to infer a temperature change for water that is consistent with theoretical estimates. This work implies that compression heating and decompression cooling are not significant enough to interfere with pressure induced protein folding studies.


Assuntos
Temperatura Baixa , Etilenoglicol/química , Temperatura Alta , Fenômenos Físicos , Pressão , Espectroscopia de Prótons por Ressonância Magnética
10.
Int J Mol Sci ; 20(24)2019 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-31817544

RESUMO

(+)-(S) and (-)-(R)-5-methyl-Wieland-Miescher ketone (+)-1 and (-)-1, are important synthons in the diastereo and enantioselective syntheses of biological and/or pharmacological interesting compounds. A key step in these syntheses is the chemoselective C(1)O acetalization to (+)-5 and (-)-5, respectively. Various procedures for this transformation have been described in the literature. Among them, the classical procedure based on the use of 1,2-ethanediol and TsOH in refluxing benzene in the presence of a Dean-Stark apparatus. Within our work on bioactive natural products, it occurred to us to observe the partial racemization of (+)-5 in the course of the acetalization of (+)-1 by means of the latter methodology. Aiming to investigate this drawback, which, to our best knowledge, has no precedents in the literature, we acetalized with 1,2-ethanediol and TsOH in refluxing benzene and in the presence of a Dean-Stark apparatus under various experimental conditions, enantiomerically pure (+)-1. It was found that the extent of racemization depends on the TsOH/(+)-1 and 1,2-ethanediol/(+)-1 ratios. Mechanism hypotheses for this partial and unexpected racemization are provided.


Assuntos
Etilenoglicol/química , Cetonas/química , Modelos Químicos , Estereoisomerismo
11.
Int J Nanomedicine ; 14: 8739-8751, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31806968

RESUMO

Objective: Nintedanib (NDNB) is a triple receptor tyrosine kinase inhibitor with poor solubility in neutral conditions and low bioavailability. A self-microemulsifying drug delivery system (SMEDDS) of NDNB was developed to improve drug solubility in physical conditions and absorption in vivo. Methods: The NDNB-SMEDDS formulation was optimized via pseudo-ternary phase diagrams. The physicochemical properties of NDNB-SMEDDS, viz., morphological observation, droplet size, stability, compatibility and in vitro release were investigated. The permeability of NDNB-SMEDDS was detected using both a Caco-2 cell monolayer in vitro and an intestinal perfusion study in vivo. Furthermore, the pharmacokinetic characteristics of NDNB-SMEDDS were evaluated. Results: The optimal formulation was composed of MCT as an oil phase, RH 40 as a surfactant and ethylene glycol as a co-surfactant. The average droplet size of the microemulsion was about 23 nm with good stability within 30 days. The formulation did not exhibit any obvious cytotoxic effect on Caco-2 cells. Permeability of nintedanib in a Caco-2 cell monolayer was enhanced by 2.8-fold upon incorporation in SMEDDS compared with the drug solution. The intestinal perfusion study demonstrated that the P app of NDNB-SMEDDS increased by 3.0-fold in the entire intestine and 3.2-fold in the colon in comparison with the drug solution. The pharmacokinetics study showed that the AUC of the NDNB-SMEDDS increased significantly. Conclusion: This study showed that the self-microemulsion formulations could improve the absorption of nintedanib, and can thus serve as a promising carrier for the oral delivery of nintedanib.


Assuntos
Sistemas de Liberação de Medicamentos/métodos , Emulsões/administração & dosagem , Indóis/administração & dosagem , Indóis/farmacocinética , Administração Oral , Animais , Disponibilidade Biológica , Células CACO-2 , Liberação Controlada de Fármacos , Emulsões/química , Emulsões/farmacocinética , Etilenoglicol/química , Humanos , Masculino , Permeabilidade , Ratos Sprague-Dawley , Solubilidade , Tensoativos/química
12.
Molecules ; 24(22)2019 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-31739495

RESUMO

Dendrons consisting of two phosphonate functions and three oligo(ethylene glycol) (OEG) chains grafted on a central phenoxyethylcarbamoylphenoxy group were synthesized and investigated as Langmuir monolayers at the surface of water. The OEG chain in the para position was grafted with a t-Bu end-group, a hydrocarbon chain, or a partially fluorinated chain. These dendrons are models of structurally related OEG dendrons that were found to significantly improve the stability of aqueous dispersions of iron oxide nanoparticles when grafted on their surface. Compression isotherms showed that all OEG dendrons formed liquid-expanded Langmuir monolayers at large molecular areas. Further compression led to a transition ascribed to the solubilization of the OEG chains in the aqueous phase. Brewster angle microscopy (BAM) provided evidence that the dendrons fitted with hydrocarbon chains formed liquid-expanded monolayers throughout compression, whilst those fitted with fluorinated end-groups formed crystalline-like domains, even at large molecular areas. Dimyristoylphosphatidylcholine and dendron molecules were partially miscible in monolayers. The deviations to ideality were larger for the dendrons fitted with a fluorocarbon end-group chain than for those fitted with a hydrocarbon chain. Brewster angle microscopy and atomic force microscopy supported the view that the dendrons were ejected from the phospholipid monolayer during the OEG conformational transition and formed crystalline domains on the surface of the monolayer.


Assuntos
Dendrímeros/química , Etilenoglicol/química , Fosfolipídeos/química , Água/química , Ar , Microscopia de Força Atômica , Propriedades de Superfície
13.
Langmuir ; 35(45): 14465-14472, 2019 11 12.
Artigo em Inglês | MEDLINE | ID: mdl-31612722

RESUMO

Catechols are prone to oxidative polymerization as well as complex formation with metal ions. These two features of catechols have played an important role in the construction of functional films on various surfaces. For example, marine antifouling films and antibacterial films were successfully prepared by oxidative polymerization and metal complexation of catechol-containing molecules, respectively. However, the effect of simultaneous metal complexation and oxidative polymerization on functional film formation has not yet been fully investigated. Herein, as a derivative of 3-(3,4-dihydroxyphenyl)-l-alanine (DOPA), we synthesized an ethylene glycol-derivatized DOPA (OEG-DOPA) and formed OEG-DOPA thin films based on (1) oxidative polymerization and (2) the complexation between catechol groups of OEG-DOPA and iron(III) (FeIII) ions. Either or both approaches were used for the film formation. OEG-DOPA film formation was characterized by ellipsometry, contact angle goniometry, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy. Among the conditions used, the formation of a uniform film was only achieved with the dual cross-linking system of FeIII complexation and oxidation-induced covalent bond formation. Compared to the uncoated substrate and other OEG-DOPA films prepared under different conditions, the uniform OEG-DOPA film strongly inhibited bacterial adhesion, showing excellent antibacterial capability. We think that our surface-coating strategy can be applied to medical devices, tools, and implants where bacterial adhesion and biofilm formation should be prevented. This work can also serve as a basis for the construction of functional thin films for other catechol-functionalized materials.


Assuntos
Antibacterianos/síntese química , Etilenoglicol/química , Compostos Férricos/síntese química , Levodopa/química , Antibacterianos/química , Compostos Férricos/química , Estrutura Molecular , Oxirredução , Tamanho da Partícula , Propriedades de Superfície
14.
Analyst ; 144(21): 6327-6333, 2019 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-31552929

RESUMO

A protein-based molecularly imprinted monolithic column was synthesized based on ionic liquids (ILs) and deep eutectic solvents (DESs) in a stainless steel column (50 mm × 4.6 mm id). An IL (1-allyl-3-butylimidazolium Br) and acrylamide were used as dual monomers. Another type of IL (1,2-bis [N,N'-vinylimidazolium] ethane bis Br) and N,N'-methylenebisacrylamide were used as dual cross-linking agents, and the DES (choline chloride : ethylene glycol 1 : 2) was used as a porogen in the preparation of a monolithic polymer. Bovine serum albumin (BSA) and lysozyme (Lyz), which differ greatly in molecular size, isoelectric point, and charge, were selected for imprinting templates to evaluate the recognition property of the green solvent-based MIP monolithic column. Some important factors, such as template-monomer molar ratio, total monomer concentration, and cross-linking density, were investigated systematically. Under optimal conditions, the MIP monolithic column obtained showed higher binding affinity for the templates than its corresponding non-imprinted (NIP) monolithic column.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Impressão Molecular , Muramidase/isolamento & purificação , Polímeros/química , Soroalbumina Bovina/isolamento & purificação , Solventes/química , Acrilamidas/química , Animais , Bovinos , Galinhas , Colina/química , Cromatografia Líquida de Alta Pressão/instrumentação , Reagentes para Ligações Cruzadas , Etilenoglicol/química , Química Verde/métodos , Líquidos Iônicos/química
15.
Biosens Bioelectron ; 143: 111636, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31476596

RESUMO

Ketamine is one of the most widely abused drugs in the world and poses a serious threat to human health and social stability; therefore, the ability to accurately monitor the substance in real-time is necessary. However, several problems still exists towards this goal, such as the generally low concentration of the target molecules disturbed in the complex samples that undergo analysis during criminal investigations. In this work, the sensitive and selective detection of ketamine was accomplished by molecularly imprinted electrochemical sensor. The molecularly imprinted membrane as a biomimetic recognition element was fabricated by the UV-induced polymerization of methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) on a metal-organic framework/graphene nanocomposite (MOFs@G) modified screen-printed electrode. The screen printed electrode (SPE) provided good adhesion for the formation of the imprinted membranes and increased the stability of the sensor. The morphology and performance of the imprinted films were characterized in detail by scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). The experimental results demonstrated that the imprinted sensor had excellent sensitivity, selectivity, and long-term stability. It offered a low detection limit (4.0 × 10-11 mol L-1) and had a dynamic range from 1.0 × 10-10 mol L-1 to 4.0 × 10-5 mol L-1. Furthermore, the established method was successfully applied for the determination of ketamine in urine and saliva samples.


Assuntos
Técnicas Biossensoriais , Grafite/isolamento & purificação , Ketamina/isolamento & purificação , Impressão Molecular , Etilenoglicol/química , Grafite/química , Humanos , Ketamina/química , Estruturas Metalorgânicas/química , Metacrilatos/química , Nanocompostos/química
16.
Biochemistry ; 58(40): 4125-4135, 2019 10 08.
Artigo em Inglês | MEDLINE | ID: mdl-31532642

RESUMO

The reaction between cytochrome c (Cc) and cytochrome c oxidase (CcO) was studied using horse cytochrome c derivatives labeled with ruthenium trisbipyridine at Cys 39 (Ru-39-Cc). Flash photolysis of a 1:1 complex between Ru-39-Cc and bovine CcO at a low ionic strength resulted in the electron transfer from photoreduced heme c to CuA with an intracomplex rate constant of k3 = 6 × 104 s-1. The K13A, K72A, K86A, and K87A Ru-39-Cc mutants had nearly the same k3 value but bound much more weakly to bovine CcO than wild-type Ru-39-Cc, indicating that lysines 13, 72, 86, and 87 were involved in electrostatic binding to CcO, but were not involved in the electron transfer pathway. The Rhodobacter sphaeroides (Rs) W143F mutant (bovine W104) caused a 450-fold decrease in k3 but did not affect the binding strength with CcO or the redox potential of CuA. These results are consistent with a computational model for Cc-CcO (Roberts and Pique ( 1999 ) J. Biol. Chem. 274 , 38051 - 38060 ) with the following electron transfer pathway: heme c → CcO-W104 → CcO-M207 → CuA. A crystal structure for the Cc-CcO complex with the proposed electron transfer pathway heme c → Cc-C14 → Cc-K13 → CcO-Y105 → CcO-M207 → CuA ( S. Shimada ( 2017 ) EMBO J. 36 , 291 - 300 ) is not consistent with the kinetic results because the K13A mutation had no effect on k3. Addition of 40% ethylene glycol (as present during the crystal preparation) decreased k3 significantly, indicating that it affected the conformation of the complex. This may explain the discrepancy between the current results and the crystallographic structure.


Assuntos
Citocromos c/química , Complexo IV da Cadeia de Transporte de Elétrons/química , Animais , Bovinos , Complexos de Coordenação/química , Cobre/química , Citocromos c/genética , Transporte de Elétrons , Etilenoglicol/química , Heme/química , Cavalos , Mutação , Fotólise , Domínios Proteicos , Rutênio/química , Rutênio/efeitos da radiação
17.
Comput Methods Programs Biomed ; 182: 105057, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31499421

RESUMO

BACKGROUND: Here we have conducted a magnetohydrodynamic (MHD) flow of viscous material with alumina water and ethylene glycol over a stretched surface. The flow is discussed with and without effective Prandtl number. MHD liquid is considered. Electric field is absent. Effect of uniform magnetic field is taken in the vertical direction to the surface. Influence of thermal radiation as well as Joule heating are taken into account for both aluminum oxide-water and aluminum oxide-Ethylene glycol nanofluids. Velocity slip and melting heat effects are considered. METHODS: The nonlinear flow expressions are numerically solved via ND-solve technique (built-in-Shooting). RESULTS: The physical impacts of flow variables like mixed convection parameter, magnetic parameter, Reynold number, Eckert number, melting parameter and heat source/sink parameter are graphically discussed. Moreover, entropy generation (irreversibility) and Bejan number are discussed graphically through various flow variables. Physical quantities like skin friction coefficient and Sherwood and Nusselt numbers are numerically calculated and discussed through Tables. CONCLUSIONS: Impact of magnetic and slip parameters on the velocity field show decreasing behavior for both effective and without effective Prandtl number. Temperature field increases for both effective and without effective Prandtl number for higher values of magnetic and radiative parameters. Entropy number is an increasing function of Reynolds number while Bejan number shows opposite impact against Reynolds number. Moreover, heat transfer rate upsurges versus larger melting and radiative parameter.


Assuntos
Alumínio/química , Entropia , Etilenoglicol/química , Hidrodinâmica , Modelos Teóricos , Nanopartículas/química
18.
Int J Mol Sci ; 20(15)2019 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-31382455

RESUMO

Recently, nanofibers (NFs) formed from antigenic peptides conjugated to ß-sheet-forming peptides have attracted much attention as a new generation of vaccines. However, studies describing how the hydrophilic-hydrophobic balance of NF components affects cellular interactions of NFs are limited. In this report, three different NFs were prepared by self-assembly of ß-sheet-forming peptides conjugated with model antigenic peptides (SIINFEKL) from ovalbumin and hydrophilic oligo-ethylene glycol (EG) of differing chain lengths (6-, 12- and 24-mer) to investigate the effect of EG length of antigen-loaded NFs on their cellular uptake, cytotoxicity, and dendritic cell (DC)-stimulation ability. We used an immortal DC line, termed JAWS II, derived from bone marrow-derived DCs of a C57BL/6 p53-knockout mouse. The uptake of NFs, consisting of the EG 12-mer by DCs, was the most effective and activated DC without exhibiting significant cytotoxicity. Increasing the EG chain length significantly reduced cellular entry and DC activation by NFs. Conversely, shortening the EG chain enhanced DC activation but increased toxicity and impaired water-dispersibility, resulting in low cellular uptake. These results show that the interaction of antigen-loaded NFs with cells can be tuned by the EG length, which provides useful design guidelines for the development of effective NF-based vaccines.


Assuntos
Adjuvantes Imunológicos/farmacologia , Antígenos/farmacologia , Células Dendríticas/efeitos dos fármacos , Ovalbumina/farmacologia , Peptídeos/farmacologia , Adjuvantes Imunológicos/química , Sequência de Aminoácidos , Animais , Antígenos/química , Linhagem Celular , Células Cultivadas , Células Dendríticas/imunologia , Etilenoglicol/química , Etilenoglicol/farmacologia , Interações Hidrofóbicas e Hidrofílicas , Camundongos Endogâmicos C57BL , Nanofibras/química , Nanofibras/ultraestrutura , Ovalbumina/química , Peptídeos/química , Conformação Proteica em Folha beta
19.
Nature ; 572(7770): 507-510, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31435058

RESUMO

The ability to manipulate droplets on a substrate using electric signals1-known as digital microfluidics-is used in optical2,3, biomedical4,5, thermal6 and electronic7 applications and has led to commercially available liquid lenses8 and diagnostics kits9,10. Such electrical actuation is mainly achieved by electrowetting, with droplets attracted towards and spreading on a conductive substrate in response to an applied voltage. To ensure strong and practical actuation, the substrate is covered with a dielectric layer and a hydrophobic topcoat for electrowetting-on-dielectric (EWOD)11-13; this increases the actuation voltage (to about 100 volts) and can compromise reliability owing to dielectric breakdown14, electric charging15 and biofouling16. Here we demonstrate droplet manipulation that uses electrical signals to induce the liquid to dewet, rather than wet, a hydrophilic conductive substrate without the need for added layers. In this electrodewetting mechanism, which is phenomenologically opposite to electrowetting, the liquid-substrate interaction is not controlled directly by electric field but instead by field-induced attachment and detachment of ionic surfactants to the substrate. We show that this actuation mechanism can perform all the basic fluidic operations of digital microfluidics using water on doped silicon wafers in air, with only ±2.5 volts of driving voltage, a few microamperes of current and about 0.015 times the critical micelle concentration of an ionic surfactant. The system can also handle common buffers and organic solvents, promising a simple and reliable microfluidic platform for a broad range of applications.


Assuntos
Eletroumectação/métodos , Microfluídica/métodos , Tensoativos/química , Acetonitrilos/química , Tampões (Química) , Dimetil Sulfóxido/química , Etilenoglicol/química , Interações Hidrofóbicas e Hidrofílicas , Íons/química , Microfluídica/instrumentação , Silício/química
20.
Int J Mol Sci ; 20(15)2019 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-31344866

RESUMO

Magnetic microspheres in a concentrated suspension can be self-assembled to form chain structures under a magnetic field, resulting in an enhanced viscosity and elasticity of the suspension (i.e., the magnetorheological (MR) effect). Recently, interest has been raised about the relationship between nonspherical particles, such as octahedral particles and the MR effect. However, experimental studies have not made much progress toward clarifying this issue due to the difficulty associated with synthesizing microparticles with well-defined shapes and sizes. Here, we presented a method for the shape-controlled synthesis of magnetite (Fe3O4) microparticles and investigated the MR effects of two suspensions prepared from the two shape-controlled samples of Fe3O4 microparticles. Our method, which was based on the polyol method, enabled the preparation of spherical and octahedral Fe3O4 microparticles with similar sizes and magnetic properties, through a reduction of α-FeOOH in a mixed solvent of ethylene glycol (a polyol) and water. The water played an important role in both the phase transition (α-FeOOH to Fe3O4) and the shape control. No substantial difference in the MR effect was observed between an octahedral-particle-based suspension and a spherical-particle-based one. Therefore, in this study, the shape of the microparticles did not strongly influence the MR effect, i.e., the properties of the chain structures.


Assuntos
Micropartículas Derivadas de Células/química , Óxido Ferroso-Férrico/síntese química , Nanopartículas de Magnetita/química , Microesferas , Etilenoglicol/química , Óxido Ferroso-Férrico/química , Campos Magnéticos , Tamanho da Partícula , Viscosidade
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