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1.
Toxicol Lett ; 331: 42-52, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32464236

RESUMO

Synthetic cathinones abuse remains a serious public health problem. Kidney injury has been reported in intoxications associated with synthetic cathinones, but the molecular mechanisms involved have not been explored yet. In this study, the potential in vitro nephrotoxic effects of four commonly abused cathinone derivatives, namely pentedrone, 3,4-dimethylmethcatinone (3,4-DMMC), methylone and 3,4-methylenedioxypyrovalerone (MDPV), were assessed in the human kidney HK-2 cell line. All four derivatives elicited cell death in a concentration- and time-dependent manner, in the following order of potency: 3,4-DMMC >> MDPV > methylone ≈ pentedrone. 3,4-DMMC and methylone were selected to further elucidate the mechanisms behind synthetic cathinones-induced cell death. Both drugs elicited apoptotic cell death and prompted the formation of acidic vesicular organelles and autophagosomes in HK-2 cells. Moreover, the autophagy inhibitor 3-methyladenine significantly potentiated cell death, indicating that autophagy may serve as a cell survival mechanism that protects renal cells against synthetic cathinones toxicity. Both drugs triggered a rise in reactive oxygen and nitrogen species formation, which was completely prevented by antioxidant treatment with N­acetyl­L­cysteine or ascorbic acid. Importantly, these antioxidant agents significantly aggravated renal cell death induced by cathinone derivatives, most likely due to their autophagy-blocking properties. Taken together, our results support an intricate control of cell survival/death modulated by oxidative stress, apoptosis and autophagy in synthetic cathinones-induced renal injury.


Assuntos
Alcaloides/toxicidade , Apoptose/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Drogas Ilícitas/toxicidade , Rim/efeitos dos fármacos , Alcaloides/química , Benzodioxóis/química , Benzodioxóis/toxicidade , Técnicas de Cultura de Células , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Humanos , Rim/metabolismo , Rim/patologia , Metanfetamina/análogos & derivados , Metanfetamina/química , Metanfetamina/toxicidade , Metilaminas/química , Metilaminas/toxicidade , Pentanonas/química , Pentanonas/toxicidade , Pirrolidinas/química , Pirrolidinas/toxicidade , Espécies Reativas de Nitrogênio/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Fatores de Tempo
2.
Phys Chem Chem Phys ; 22(9): 5301-5313, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32096507

RESUMO

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


Assuntos
Caprolactama/análogos & derivados , Metilaminas/química , Simulação de Dinâmica Molecular , Polímeros/química , Betaína/química , Caprolactama/química , Interações Hidrofóbicas e Hidrofílicas , Conformação Molecular , Transição de Fase , Sarcosina/química , Temperatura de Transição , Água/química
3.
Chem Commun (Camb) ; 56(8): 1187-1190, 2020 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-31922177

RESUMO

Trimethylamine N-oxide is found to be effective in regulating the interaction between microtubules and kinesins over a wide temperature range. The lifetime of the motility of microtubules on kinesins at high temperatures is prolonged using trimethylamine N-oxide. The activation energy of microtubule motility is increased by trimethylamine N-oxide. Prolonged operation at high temperatures decreased the activation energy of MT motility despite the increase in concentration of trimethylamine N-oxide.


Assuntos
Cinesina/metabolismo , Metilaminas/farmacologia , Microtúbulos/metabolismo , Temperatura , Cinesina/química , Cinética , Metilaminas/química , Microtúbulos/química
4.
J Environ Sci Health B ; 55(3): 239-249, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31680618

RESUMO

Heavy metals can be highly toxic depending on the dose and the chemical form. In this context, sensing devices such as nanobiosensors have been presented as a promising tool to monitor contaminants at micro and nanoscale. In this work, cantilever nanobiosensors with phosphatase alkaline were developed and applied to detect heavy metals (Pb, Ni, Cd, Zn, Co, and Al) in river water. The nanobiosensor surface was functionalized by the self-assembled monolayers (SAM) technique using 16-mercaptohexadecanoic acid, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) and N- hydroxysuccinimide (NHS), and phosphatase alkaline enzyme. The sensing layer deposited on the cantilever surface presented a uniform morphology, at nanoscale, with 80 nm of thickness. The nanobiosensor showed a detection limit in the ppb range and high sensitivity, with a stability of fifteen days. The developed cantilever nanobiosensor is a simple tool, suitable for the direct detection of contaminants in river water.


Assuntos
Técnicas Biossensoriais/instrumentação , Metais Pesados/análise , Rios/química , Poluentes Químicos da Água/análise , Fosfatase Alcalina/química , Fosfatase Alcalina/metabolismo , Técnicas Biossensoriais/métodos , Brasil , Carbodi-Imidas/química , Monitoramento Ambiental/instrumentação , Monitoramento Ambiental/métodos , Desenho de Equipamento , Limite de Detecção , Metilaminas/química , Ácidos Palmíticos/química , Sensibilidade e Especificidade
5.
Biosens Bioelectron ; 148: 111666, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31698301

RESUMO

As an essential transition-metal ion in organism, zinc ion (Zn2+) plays a significant role in cellular metabolism, apoptosis and neurotransmission. Herein, we reported a new intramolecular charge transfer-based two-photon probe, (E)-1-(6-(4-(2-(2-(2-methoxyethoxy)ethoxy)eth-oxy)-3,5-dimethylstyryl)quinolin-2-yl)-N,N-bis(pyridin-2-ylmethyl)methanamine (TEO-MPVQ), for ratiometric imaging and biosensing of Zn2+ in living cells and larval zebrafish. The maximum two-photon absorption cross-section values (δmax) of the developed probe increased from 115 ±â€¯16 GM to 188 ±â€¯27 GM, after the probe was chelated with Zn2+. The emission spectrum of TEO-MPVQ probe increased and red-shifted about 60 nm, resulting in the ratiometric determination of Zn2+ with high sensitivity and selectivity. The present fluorescent probe also demonstrated good biocompatibility, high spatial resolution and deep penetration depth for Zn2+ detection. Accordingly, TEO-MPVQ was able to track the endogenous Zn2+ release in neurons and also successfully applied for larval zebrafish imaging. By using of this effective probe, it was found that the endogenous Zn2+ was rapidly released from metallothionein under the stimulation of NO in neurons.


Assuntos
Técnicas Biossensoriais/métodos , Corantes Fluorescentes/química , Neurônios/química , Imagem Óptica/métodos , Peixe-Zebra , Zinco/análise , Animais , Cátions Bivalentes/análise , Larva/química , Metilaminas/química , Camundongos , Microscopia de Fluorescência por Excitação Multifotônica/métodos , Neurônios/citologia , Quinolinas/química , Espectrometria de Fluorescência/métodos , Peixe-Zebra/metabolismo
6.
Biophys Chem ; 257: 106258, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31881504

RESUMO

Recent methodological progress in quantum-chemical calculations using the "embedded cluster reference interaction site model" (EC-RISM) integral equation theory is reviewed in the context of applying it as a solvation model for calculating pressure-dependent thermodynamic and spectroscopic properties of molecules immersed in water. The methodology is based on self-consistent calculations of electronic and solvation structure around dissolved molecules where pressure enters the equations via an appropriately chosen solvent response function and the pure solvent density. Besides specification of a dispersion-repulsion force field for solute-solvent interactions, the EC-RISM approach derives the electrostatic interaction contributions directly from the wave function. We further develop and apply the method to a variety of benchmark cases for which computational or experimental reference data are either available in the literature or are generated specifically for this purpose in this work. Starting with an enhancement to predict hydration free energies at non-ambient pressures, which is the basis for pressure-dependent molecular population estimation, we demonstrate the performance on the calculation of the autoionization constant of water. Spectroscopic problems are addressed by studying the biologically relevant small osmolyte TMAO (trimethylamine N-oxide). Pressure-dependent NMR shifts are predicted and compared to experiments taking into account proper computational referencing methods that extend earlier work. The experimentally observed IR blue-shifts of certain vibrational bands of TMAO as well as of the cyanide anion are reproduced by novel methodology that allows for weighing equilibrium and non-equilibrium solvent relaxation effects. Taken together, the model systems investigated allow for an assessment of the reliability of the EC-RISM approach for studying pressure-dependent biophysical processes.


Assuntos
Modelos Químicos , Espectroscopia de Ressonância Magnética , Metilaminas/síntese química , Metilaminas/química , Simulação de Dinâmica Molecular , Pressão , Teoria Quântica
7.
J Enzyme Inhib Med Chem ; 34(1): 712-727, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31852270

RESUMO

The design of multi-target directed ligands (MTDLs) is a valid approach for obtaining effective drugs for complex pathologies. MTDLs that combine neuro-repair properties and block the first steps of neurotoxic cascades could be the so long wanted remedies to treat neurodegenerative diseases (NDs). By linking two privileged scaffolds with well-known activities in ND-targets, the flavonoid and the N,N-dibenzyl(N-methyl)amine (DBMA) fragments, new CNS-permeable flavonoid - DBMA hybrids (1-13) were obtained. They were subjected to biological evaluation in a battery of targets involved in Alzheimer's disease (AD) and other NDs, namely human cholinesterases (hAChE/hBuChE), ß-secretase (hBACE-1), monoamine oxidases (hMAO-A/B), lipoxygenase-5 (hLOX-5) and sigma receptors (σ1R/σ2R). After a funnel-type screening, 6,7-dimethoxychromone - DBMA (6) was highlighted due to its neurogenic properties and an interesting MTD-profile in hAChE, hLOX-5, hBACE-1 and σ1R. Molecular dynamic simulations showed the most relevant drug-protein interactions of hybrid 6, which could synergistically contribute to neuronal regeneration and block neurodegeneration.


Assuntos
Doença de Alzheimer/tratamento farmacológico , Inibidores Enzimáticos/farmacologia , Flavonoides/farmacologia , Metilaminas/farmacologia , Regeneração Nervosa/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Acetilcolinesterase/metabolismo , Doença de Alzheimer/metabolismo , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Secretases da Proteína Precursora do Amiloide/metabolismo , Animais , Araquidonato 5-Lipoxigenase/metabolismo , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Ácido Aspártico Endopeptidases/metabolismo , Barreira Hematoencefálica/efeitos dos fármacos , Barreira Hematoencefálica/metabolismo , Butirilcolinesterase/metabolismo , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Flavonoides/química , Humanos , Masculino , Metilaminas/química , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Modelos Moleculares , Estrutura Molecular , Monoaminoxidase/metabolismo , Fármacos Neuroprotetores/síntese química , Fármacos Neuroprotetores/química
8.
Phys Chem Chem Phys ; 21(40): 22224-22229, 2019 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-31576857

RESUMO

The application of co-solvents and high pressure has been reported to be an efficient means to tune the kinetics of enzyme-catalyzed reactions. Co-solvents and pressure can lead to increased reaction rates without sacrificing enzyme stability, while temperature and pH operation windows are generally very narrow. Quantitative prediction of co-solvent and pressure effects on enzymatic reactions has not been successfully addressed in the literature. Herein, we are introducing a thermodynamic approach that is based on molecular interactions in the form of activity coefficients of substrate and of enzyme in the multi-component solution. This allowed us to quantitatively predict the combined effect of co-solvent and pressure on the kinetic constants, i.e. the Michaelis constant KM and the catalytic constant kcat, of an α-CT-catalyzed peptide hydrolysis reaction. The reaction was studied in the presence of different types of co-solvents and at pressures up to 2 kbar, and quantitative predictions could be obtained for KM, kcat, and finally even primary Michaelis-Menten plots using activity coefficients provided by the thermodynamic model PC-SAFT.


Assuntos
Quimotripsina/química , Fenilalanina/análogos & derivados , Dimetil Sulfóxido/química , Hidrólise , Cinética , Metilaminas/química , Fenilalanina/química , Pressão , Solventes/química , Termodinâmica , Ureia/química , Água/química
9.
Phys Chem Chem Phys ; 21(37): 21038-21048, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31528920

RESUMO

Dramatically different properties have been observed for two types of osmolytes, i.e., trimethylamine N-oxide (TMAO) and urea, in a protein folding process. Great progress has been made in revealing the potential underlying mechanism of these two osmolyte systems. However, many problems still remain unsolved. In this paper, we propose to use the persistent homology to systematically study the osmolytes' molecular aggregation and their hydrogen-bonding network from a global topological perspective. It has been found that, for the first time, TMAO and urea show two extremely different topological behaviors, i.e., an extensive network and local clusters, respectively. In general, TMAO forms highly consistent large loop or circle structures in high concentrations. In contrast, urea is more tightly aggregated locally. Moreover, the resulting hydrogen-bonding networks also demonstrate distinguishable features. With a concentration increase, TMAO hydrogen-bonding networks vary greatly in their total number of loop structures and large-sized loop structures consistently increase. In contrast, urea hydrogen-bonding networks remain relatively stable with slight reduction of the total loop number. Moreover, the persistent entropy (PE) is, for the first time, used in characterization of the topological information of the aggregation and hydrogen-bonding networks. The average PE systematically increases with the concentration for both TMAO and urea, and decreases in their hydrogen-bonding networks. But their PE variances have totally different behaviors. Finally, topological features of the hydrogen-bonding networks are found to be highly consistent with those from the ion aggregation systems, indicating that our topological invariants can characterize intrinsic features of the "structure making" and "structure breaking" systems.


Assuntos
Metilaminas/química , Ureia/química , Entropia , Hidrogênio/química , Ligação de Hidrogênio , Simulação de Dinâmica Molecular , Agregação Patológica de Proteínas , Homologia Estrutural de Proteína
10.
Biophys Chem ; 253: 106222, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31421516

RESUMO

We present measurements, molecular dynamics (MD) simulations, and predictions using Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) of the density of aqueous solutions in a pressure range from 1 bar to 5000 bar, a pressure regime that is highly relevant for both biochemical applications and the fundamental understanding of solvation. The accurate determination of density data of pressurized solutions remains challenging. We determined relative density changes from the variations in X-ray absorption through the sample and developed a new water parameter set for PC-SAFT modeling that is appropriate for high pressure conditions in the kilobar regime. As a showcase, we studied trimethylamine N-oxide (TMAO) solutions and demonstrated that their compressibility decreases with the TMAO content. This result is linked to the stabilizing effect of TMAO on the local H-bond network of water. Experiments and calculations, which represent two independent methods, are in very good agreement and are in accordance with results of force field molecular dynamics simulations of the same systems.


Assuntos
Metilaminas/química , Simulação de Dinâmica Molecular , Ligação de Hidrogênio , Modelos Estatísticos , Soluções
11.
Eur J Med Chem ; 182: 111626, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31445232

RESUMO

A new series of fluorinated 5-HT2C agonists were designed and synthesized on the basis of our previous work on 2-phenylcyclopropylmethylamines as a potential approach for the treatment of central nervous system disorders. Key fluorinated cyclopropane moieties were constructed through transition metal catalyzed [2 + 1]-cycloaddition of aromatic vinyl fluorides, and the absolute stereochemistry of the representative compound (-)-21a was established. Functional activity measuring calcium flux at 5-HT2 receptors reveals high potency for compounds (+)-21a-d. In particular, (+)-21b had no detectable 5-HT2B agonism and displayed reasonable selectivity against 5-HT2A. Molecular docking studies were further performed to explain the compounds' possible binding poses to the 5-HT2C receptor.


Assuntos
Ciclopropanos/farmacologia , Desenho de Fármacos , Metilaminas/farmacologia , Receptor 5-HT2C de Serotonina/metabolismo , Ciclopropanos/síntese química , Ciclopropanos/química , Relação Dose-Resposta a Droga , Halogenação , Humanos , Metilaminas/síntese química , Metilaminas/química , Simulação de Acoplamento Molecular , Estrutura Molecular , Receptor 5-HT2B de Serotonina/metabolismo , Relação Estrutura-Atividade
12.
Phys Chem Chem Phys ; 21(35): 19469-19479, 2019 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-31461098

RESUMO

Using all-atom molecular dynamics simulations of aqueous solutions of the globular protein SNase, the dynamic behavior of water molecules and cosolvents (trimethylamine-N-oxide (TMAO) and urea) in the hydration shell of the protein was studied for different solvent compositions. TMAO is a potent protein-stabilizing osmolyte, whereas urea is known to destabilize proteins. For molecules that are initially located in successive narrow layers at a given distance from the protein, the mean displacements and the distribution of displacements for short time intervals are calculated. For molecules that are initially located in solvation shells of a given thickness around the protein, the characteristic residence times in these shells are determined to characterize the dynamic behavior of the solvent molecules as a function of the distance to the protein. A combined consideration of these characteristics allows to reveal additional features of the dynamics of the cosolvents. It is shown that TMAO molecules leave the nearest vicinity of the protein faster than urea molecules, despite the fact that the mobility of TMAO molecules, measured by their mean displacements, is lower than that of urea. Moreover, we show that the rate of release of TMAO molecules from the hydration shell is lower in ternary (TMAO + urea + H2O) solvent mixtures than in the binary ones. This is consistent with a recent observation that the fraction of TMAO near the protein decreases in the presence of urea. From the analysis of the decay of the number of particles initially located in the region of the first peak of the distribution function of solvent molecules around the protein, we estimated that about 20 water molecules and 6-7 urea molecules stay near the protein for more than 1000 ps.


Assuntos
Endodesoxirribonucleases/química , Endodesoxirribonucleases/metabolismo , Metilaminas/química , Simulação de Dinâmica Molecular , Ureia/química , Água/química , Estabilidade Proteica , Solventes/química
13.
Talanta ; 204: 592-601, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31357339

RESUMO

Development of conjugated polymers with fluorescence sensing characteristics has received close attention from researchers in fields of environmental protection, biosensing and toxins detection on food. In this paper, novel polyaniline derivatives of poly(9-methyl-9H-carbazol-3-amine) and poly(9,9-dihexyl-9H-fluoren-2-amine) are prepared by facile chemical polymerization. Then they are characterized with NMR (Nuclear Magnetic Resonance), GPC (Gel Permeation Chromatography), XRD (X-Ray Diffraction), FT-IR (Fourier Transform Infrared spectroscopy), FL (Fluorescence spectrometry) and UV-vis (Ultraviolet-visible spectroscopy) characterizations and further applied to the fluorescence detection of different acids and amines. Moreover, the obtained poly(9-methyl-9H-carbazol-3-amine) displays excellent fluorescence properties in the detection for both acids and amines. Besides, this poly(9-methyl-9H-carbazol-3-amine) can not only be used for fluorescence detection in solution, but also can be prepared into solid state and applied in the gas phase fluorescence detection. This work has greatly expanded the scope of application to these polyaniline derivatives materials, opening a new path for the researches on multi-functional chemosensor.


Assuntos
Compostos de Anilina/química , Carbazóis/química , Fluorenos/química , Corantes Fluorescentes/química , Compostos de Anilina/síntese química , Carbazóis/síntese química , Etilenodiaminas/análise , Etilenodiaminas/química , Fluorenos/síntese química , Fluorescência , Corantes Fluorescentes/síntese química , Ácido Clorídrico/análise , Ácido Clorídrico/química , Ligação de Hidrogênio , Limite de Detecção , Metilaminas/análise , Metilaminas/química , Ácido Nítrico/análise , Ácido Nítrico/química , Reprodutibilidade dos Testes , Espectrometria de Fluorescência/métodos
14.
Molecules ; 24(15)2019 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-31357491

RESUMO

Human sirtuin 2 (SIRT2), a member of the sirtuin family, has been considered as a promising drug target in cancer, neurodegenerative diseases, type II diabetes, and bacterial infections. Thus, SIRT2 inhibitors have been involved in effective treatment strategies for related diseases. Using previously established fluorescence-based assays for SIRT2 activity tests, the authors screened their in-house database and identified a compound, 4-(5-((3-(quinolin-5-yl)ureido)methyl)furan-2-yl)benzoic acid (20), which displayed 63 ± 5% and 35 ± 3% inhibition against SIRT2 at 100 µM and 10 µM, respectively. The structure-activity relationship (SAR) analyses of a series of synthesized (5-phenylfuran-2-yl)methanamine derivatives led to the identification of a potent compound 25 with an IC50 value of 2.47 µM, which is more potent than AGK2 (IC50 = 17.75 µM). Meanwhile, 25 likely possesses better water solubility (cLogP = 1.63 and cLogS = -3.63). Finally, the molecular docking analyses indicated that 25 fitted well with the induced hydrophobic pocket of SIRT2.


Assuntos
Descoberta de Drogas , Inibidores de Histona Desacetilases/química , Metilaminas/química , Sirtuína 2/química , Inibidores de Histona Desacetilases/farmacologia , Humanos , Metilaminas/farmacologia , Modelos Moleculares , Conformação Molecular , Estrutura Molecular , Sirtuína 2/antagonistas & inibidores , Relação Estrutura-Atividade
15.
J Am Soc Mass Spectrom ; 30(8): 1385-1388, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31286443

RESUMO

Modulating protein ion charge is a useful tool for the study of protein folding and interactions by electrospray ionization mass spectrometry. Here, we investigate activation-dependent charge reduction of protein ions with the chemical chaperone trimethylamine-N-oxide (TMAO). Based on experiments carried out on proteins ranging from 4.5 to 35 kDa, we find that when combined with collisional activation, TMAO removes approximately 60% of the charges acquired under native conditions. Ion mobility measurements furthermore show that TMAO-mediated charge reduction produces the same end charge state and arrival time distributions for native-like and denatured protein ions. Our results suggest that gas-phase collisions between the protein ions and TMAO result in proton transfer, in line with previous findings for dimethyl- and trimethylamine. By adjusting the energy of the collisions experienced by the ions, it is possible to control the degree of charge reduction, making TMAO a highly dynamic charge reducer that opens new avenues for manipulating protein charge states in ESI-MS and for investigating the relationship between protein charge and conformation. ᅟ.


Assuntos
Metilaminas/química , Proteínas/química , Espectrometria de Massas por Ionização por Electrospray/métodos , Gases/química , Humanos , Íons/química , Modelos Moleculares , Conformação Proteica , Desnaturação Proteica , Dobramento de Proteína
16.
Biopolymers ; 110(9): e23318, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31274198

RESUMO

Stimuli-responsive polymers that can undergo conformational changes with external triggers have enabled themselves as smart materials for various utilizations, among which biodegradability is of particular importance to be engineered for biomedical application. In this study, a thermo and pH dual responsive polypeptide (N, N-dimethylaminoethyl acrylate-modified poly(l-cysteine)) (PLC-g-DMAEA) was prepared by the combination of N-carboxyanhydride ring-open polymerization and thiol-ene click chemistry. The biodegradable poly(l-cysteine) (PLC) with pendant thiol groups provided an easily clickable backbone for postmodification, which was demonstrated by reacting with a well-known monomer of N, N-dimethylaminoethyl acrylate (DMAEA) to achieve both temperature and pH responsiveness. The irreversible thermo-response of PLC-g-DMAEA could be attributed to the ordered ß-sheets formed upon heating, leading to the trapped side groups with poor water accessibility. Moreover, this copolymer precipitated at pH ranging from 7.5 to 9.7, but protonation of tertiary amine groups (pH < 7.5) and salt forming of masked thiol groups (pH > 9.7) rendered it soluble in water. Our results revealed that a ready available vinyl monomer could be easily clicked onto the biodegradable PLC and its stimuli responsiveness would be reserved. Moreover, the primary and secondary structures of PLC might influence the conformation, thus leading to the unique responsive behavior of the resulted copolymer.


Assuntos
Acrilatos/química , Metilaminas/química , Peptídeos/síntese química , Química Click , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética , Peptídeos/química , Transição de Fase , Polimerização , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Compostos de Sulfidrila/química , Temperatura
17.
ACS Appl Mater Interfaces ; 11(30): 27279-27287, 2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31265242

RESUMO

This work introduces a piezoelectric-pyroelectric nanogenerator (P-PNG) based on methylammonium lead iodide (CH3NH3PbI3) incorporated electrospun poly(vinylidene fluoride) (PVDF) nanofibers that are able to harvest mechanical and thermal energies. During the application of a periodic compressive contact force at a frequency of 4 Hz, an output voltage of ∼220 mV is generated. The P-PNG has a piezoelectric coefficient (d33) of ∼19.7 pC/N coupled with a high durability (60 000 cycles) and quick response time (∼1 ms). The maximum generated output power density (∼0.8 mW/m2) is sufficient to charge up a variety of capacitors, with the potential to replace an external power supply to drive portable devices. In addition, upon exposure to cyclic heating and cooling at a temperature of 38 K, a pyroelectric output current of 18.2 pA and a voltage of 41.78 mV were achieved. The fast response time of 1.14 s, reset time of 1.25 s, and pyroelectric coefficient of ∼44 pC/m2 K demonstrate a self-powered temperature sensing capability of the P-PNG. These characteristics make the P-PNG suitable for flexible piezoelectric-pyroelectric energy harvesting for self-powered electronic devices.


Assuntos
Fontes de Energia Elétrica , Metilaminas/química , Nanofibras/química , Iodetos/química , Chumbo/química , Transição de Fase , Polivinil/química
18.
Nutrients ; 11(7)2019 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-31336819

RESUMO

Medicines containing citicoline (cytidine-diphosphocholine) as an active principle have been marketed since the 1970s as nootropic and psychostimulant drugs available on prescription. Recently, the inner salt variant of this substance was pronounced a food ingredient in the major world markets. However, in the EU no nutrition or health claim has been authorized for use in commercial communications concerning its properties. Citicoline is considered a dietetic source of choline and cytidine. Cytidine does not have any health claim authorized either, but there are claims authorized for choline, concerning its contribution to normal lipid metabolism, maintenance of normal liver function, and normal homocysteine metabolism. The applicability of these claims to citicoline is discussed, leading to the conclusion that the issue is not a trivial one. Intriguing data, showing that on a molar mass basis citicoline is significantly less toxic than choline, are also analyzed. It is hypothesized that, compared to choline moiety in other dietary sources such as phosphatidylcholine, choline in citicoline is less prone to conversion to trimethylamine (TMA) and its putative atherogenic N-oxide (TMAO). Epidemiological studies have suggested that choline supplementation may improve cognitive performance, and for this application citicoline may be safer and more efficacious.


Assuntos
Citidina Difosfato Colina/química , Citidina Difosfato Colina/farmacologia , Citidina Difosfato Colina/efeitos adversos , Citidina Difosfato Colina/metabolismo , Suplementos Nutricionais , Relação Dose-Resposta a Droga , União Europeia , Análise de Alimentos , Humanos , Metilaminas/efeitos adversos , Metilaminas/química , Metilaminas/metabolismo
19.
Phys Chem Chem Phys ; 21(24): 12806-12817, 2019 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-31165827

RESUMO

We present a study of the combined effects of natural cosolvents (TMAO, glycine, urea) and pressure on the activity of the tetrameric enzyme lactate dehydrogenase (LDH). To this end, high-pressure stopped-flow methodology in concert with fast UV/Vis spectroscopic detection of product formation was applied. To reveal possible pressure effects on the stability and dynamics of the enzyme, FTIR spectroscopic and neutron scattering measurements were carried out. In neat buffer solution, the catalytic turnover number of the enzyme, kcat, increases up to 1000 bar, the pressure range where dissociation of the tetrameric species to dimers sets in. Accordingly, we obtain a negative activation volume, ΔV# = -45.3 mL mol-1. Further, the enzyme substrate complex has a larger volume compared to the enzyme and substrate in the unbound state. The neutron scattering data show that changes in the fast internal dynamics of the enzyme are not responsible for the increase of kcat upon compression. Whereas the magnitude of kcat is similar in the presence of the osmolytes, the pressure of deactivation is modulated by the addition of cosolvents. TMAO and glycine increase the pressure of deactivation, and in accordance with the observed stabilizing effect both cosolvents exhibit against denaturation and/or dissociation of proteins. While urea does not markedly affect the magnitude of the Michaelis constant, KM, both 1 M TMAO and 1 M glycine exhibit smaller KM values of about 0.07 mM and 0.05 mM below about 1 kbar. Such positive effect on the substrate affinity could be rationalized by the effect the two cosolutes impose on the thermodynamic activities of the reactants, which reflect changes in water-mediated intermolecular interactions. Our data show that the intracellular milieu, i.e., the solution conditions that have evolved, may be sufficient to maintain enzymatic activity under extreme environmental conditions, including the whole pressure range encountered on Earth.


Assuntos
L-Lactato Desidrogenase/química , Solventes/química , Glicina/química , Cinética , Metilaminas/química , Modelos Moleculares , Pressão , Desnaturação Proteica , Dobramento de Proteína , Multimerização Proteica , Termodinâmica , Ureia/química , Água/química
20.
Sci Adv ; 5(6): eaaw9562, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31214655

RESUMO

Materials that resist nonspecific protein adsorption are needed for many applications. However, few are able to achieve ultralow fouling in complex biological milieu. Zwitterionic polymers emerge as a class of highly effective ultralow fouling materials due to their superhydrophilicity, outperforming other hydrophilic materials such as poly(ethylene glycol). Unfortunately, there are only three major classes of zwitterionic materials based on poly(phosphorylcholine), poly(sulfobetaine), and poly(carboxybetaine) currently available. Inspired by trimethylamine N-oxide (TMAO), a zwitterionic osmolyte and the most effective protein stabilizer, we here report TMAO-derived zwitterionic polymers (PTMAO) as a new class of ultralow fouling biomaterials. The nonfouling properties of PTMAO were demonstrated under highly challenging conditions. The mechanism accounting for the extraordinary hydration of PTMAO was elucidated by molecular dynamics simulations. The discovery of PTMAO polymers demonstrates the power of molecular understanding in the design of new biomimetic materials and provides the biomaterials community with another class of nonfouling zwitterionic materials.


Assuntos
Materiais Biocompatíveis/química , Incrustação Biológica/prevenção & controle , Metilaminas/química , Polímeros/química , Adsorção , Animais , Materiais Biocompatíveis/metabolismo , Materiais Biocompatíveis/farmacologia , Adesão Celular/efeitos dos fármacos , Humanos , Metilaminas/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Simulação de Dinâmica Molecular , Células NIH 3T3 , Polímeros/metabolismo , Polímeros/farmacologia , Albumina Sérica/química , Ressonância de Plasmônio de Superfície
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