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1.
Metallomics ; 16(5)2024 05 02.
Artigo em Inglês | MEDLINE | ID: mdl-38599629

RESUMO

Taking into account that in recent decades there has been an increase in the incidence of urinary stones, especially in highly developed countries, from a wide range of potentially harmful substances commonly available in such countries, we chose zinc for the research presented in this article, which is classified by some sources as a heavy metal. In this article, we present the results of research on the influence of Zn2+ ion on the nucleation and growth of struvite crystals-the main component of infection urinary stones. The tests were carried out in an artificial urine environment with and without the presence of Proteus mirabilis bacteria. In the latter case, the activity of bacterial urease was simulated chemically, by systematic addition of an aqueous ammonia solution. The obtained results indicate that Zn2+ ions compete with Mg2+ ions, which leads to the gradual replacement of Mg2+ ions in the struvite crystal lattice with Zn2+ ions to some extent. This means co-precipitation of Mg-struvite (MgNH4PO4·6H2O) and Znx-struvite (Mg1-xZnxNH4PO4·6H2O). Speciation analysis of chemical complexes showed that Znx-struvite precipitates at slightly lower pH values than Mg-struvite. This means that Zn2+ ions shift the nucleation point of crystalline solids towards a lower pH. Additionally, the conducted research shows that Zn2+ ions, in the range of tested concentrations, do not have a toxic effect on bacteria; on the contrary, it has a positive effect on cellular metabolism, enabling bacteria to develop better. It means that Zn2+ ions in artificial urine, in vitro, slightly increase the risk of developing infection urinary stones.


Assuntos
Proteus mirabilis , Estruvita , Cálculos Urinários , Zinco , Estruvita/química , Zinco/metabolismo , Zinco/química , Cálculos Urinários/química , Cálculos Urinários/metabolismo , Cálculos Urinários/microbiologia , Proteus mirabilis/metabolismo , Humanos , Fosfatos/metabolismo , Fosfatos/química , Íons , Compostos de Magnésio/metabolismo , Compostos de Magnésio/química , Cristalização
2.
J Mater Chem B ; 9(7): 1888-1895, 2021 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-33533362

RESUMO

It remains a major challenge to achieve efficient oral delivery and controlled intestinal release of ions using hydrogels. Herein, we report a novel, pH/redox-dual responsive, nanoemulsion-embedded composite hydrogel to address this issue. The hydrogel was first synthesized by crosslinking a biocompatible, pH-responsive pseudopeptide, poly(l-lysine isophthalamide) (PLP), and redox-sensitive l-cystine dimethyl ester dihydrochloride (CDE). A suitable amount of magnesium acetate was encapsulated into oil-in-water nanoemulsions, which were then embedded into the lysine-based hydrogel. The resulting composite hydrogel collapsed into a compact structure at acidic gastric pH, but became highly swollen or degraded in the neutral and reducing intestinal environment. The ion release profiles indicated that the nanoemulsion-embedded composite hydrogel could well retain and protect magnesium ions in the simulated gastric fluid (SGF) buffer at pH 1.2, but efficiently release them in the simulated intestinal fluid (SIF) buffer at pH 6.8 in the presence of 1,4-dithiothreitol (DTT) as a reducing agent. Moreover, this composite hydrogel system displayed good biocompatibility. These results suggested that the pH/redox-dual responsive, nanoemulsion-embedded composite hydrogel could be a promising candidate for efficient oral delivery and controlled intestinal release of magnesium and other ions.


Assuntos
Acetatos/metabolismo , Sistemas de Liberação de Medicamentos , Hidrogéis/metabolismo , Intestinos/química , Compostos de Magnésio/metabolismo , Nanopartículas/metabolismo , Acetatos/administração & dosagem , Acetatos/química , Administração Oral , Emulsões/química , Emulsões/metabolismo , Células HeLa , Humanos , Hidrogéis/síntese química , Hidrogéis/química , Concentração de Íons de Hidrogênio , Íons/administração & dosagem , Íons/química , Íons/metabolismo , Compostos de Magnésio/administração & dosagem , Compostos de Magnésio/química , Estrutura Molecular , Nanopartículas/química , Oxirredução , Tamanho da Partícula , Propriedades de Superfície
3.
Astrobiology ; 20(9): 1067-1075, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32833498

RESUMO

We present the hypothesis that microorganisms can change the freezing/melting curve of cold salty solutions by protein expression, as it is known that proteins can affect the liquid-to-ice transition, an ability that could be of ecological advantage for organisms on Earth and on Mars. We tested our hypothesis by identifying a suitable candidate, the well-known psycrophile and halotolerant bacteria Rhodococcus sp. JG3, and analyzing its response in culture conditions that included specific hygroscopic salts relevant to Mars-that is, highly concentrated magnesium perchlorate solutions of 20 wt % and 50 wt % Mg(ClO4)2 at both end members of the eutectic concentration (44 wt %)-and subfreezing temperatures (263 K and 253 K). Using a combination of techniques of molecular microbiology and aqueous geochemistry, we evaluated the potential roles of proteins over- or underexpressed as important players in different mechanisms for the adaptability of life to cold environments. We recorded the changes observed by micro-differential scanning calorimetry. Unfortunately, Rhodococcus sp. JG3 did not show our hypothesized effect on the melting characteristics of cold Mg-perchlorate solutions. However, the question remains as to whether our novel hypothesis that halophilic/psychrophilic bacteria or archaea can alter the freezing/melting curve of salt solutions could be validated. The null result obtained after analyzing just one case lays the foundation to continue the search for proteins produced by microorganisms that thrive in very cold, high-saline solutions, which would involve testing different microorganisms with different salt components. The immediate implications for the habitability of Mars are discussed.


Assuntos
Proteínas de Bactérias/genética , Meio Ambiente Extraterreno/química , Compostos de Magnésio/química , Marte , Percloratos/química , Rhodococcus/metabolismo , Proteínas de Bactérias/metabolismo , Exobiologia/métodos , Congelamento , Regulação Bacteriana da Expressão Gênica , Compostos de Magnésio/metabolismo , Percloratos/metabolismo , Rhodococcus/química , Temperatura de Transição , Água/química , Microbiologia da Água
4.
Eur J Pharm Biopharm ; 154: 270-282, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32717386

RESUMO

This study reports the use of ITC in understanding the thermodynamics occurring for a controlled release system in which complexation has been exploited. In this study, a model drug, propranolol hydrochloride (PPN) was complexed with magnesium aluminium silicate (MAS) and these complexes were used in combination with polyethylene oxide (PEO) as a hydrophilic carrier at various concentrations to sustain the release of PPN. DSC, XRPD, ATR-FTIR and SEM/EDX were successfully used in characterising the produced complexes. 2D- SAXS data patterns for MAS and the produced complexes were shown to be symmetric and circular with the particles showing no preferred orientation at the nanometre scale. ITC studies showed differences between PPN adsorption onto MAS compared with PPN adsorption onto a MAS-PEO mixture. At both temperatures studied the binding affinity Ka was greater for the titration of PPN into the MAS-PEO mixture (5.37E + 04 ± 7.54E + 03 M at 25 °C and 8.63E + 04 ± 6.11E + 03 M at 37 °C), compared to the affinity obtained upon binding between PPN and MAS as previously reported suggesting a stronger binding with implications for the dissolution process. MAS-PPN complexes with the PEO polymer compacts displayed desired manufacturing and formulation properties for a formulator including, reduced plastic recovery therefore potentially reducing the risk of cracking/splitting and on tooling wear, controlled release of PPN at a significantly low (5%) polymer level as well as a zero-order release profile (case II transport) using up to 50% polymer level.


Assuntos
Compostos de Alumínio/análise , Liberação Controlada de Fármacos , Compostos de Magnésio/análise , Nanocompostos/análise , Polímeros/análise , Espalhamento a Baixo Ângulo , Silicatos/análise , Compostos de Alumínio/metabolismo , Compostos de Magnésio/metabolismo , Polímeros/metabolismo , Silicatos/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier/métodos
5.
Life Sci ; 257: 117999, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32585244

RESUMO

AIM: This paper was mainly aimed at synthesis of Ce-containing nano-Mg-phosphate ceramic as a multifunctional material. MATERIALS AND METHODS: Two ceramics based on Mg3(PO4)2 and Ce0.2Mg2.8(PO4)2 formulas (MP and MP-C, respectively) were synthesized. The synthesized powders were characterized by XRD, TEM, Zeta potential, and FTIR. Also, their dissolution behavior was tested in Tris-HCl buffer solution. Moreover, the antimicrobial efficacy was evaluated against gram-positive bacteria (Bacillus sphaericus MTCC 511 &Staphylococcus aureus MTCC 87) and gram-negative bacteria (Enterobacter aerogenes MTCC 111 &Pseudomonas aeruginosa MTCC 1034) using dick diffusion assay and microdilution method. Furthermore, the cell viability test was performed for the ceramics on Vero cells (African green monkey kidney cells), and their antitumor activity was determined by PC3 cell line (prostatic cancer). Also, the cellular uptake was determined by the flow cytometry. KEY FINDINGS: The results showed that the substitution of Mg by Ce decreased the particle size from 40 to 90 nm for MP sample to 2-10 nm for MP-C sample and increased the degradation rate. Both samples showed excellent antimicrobial activities. Moreover, MP demonstrated more cell viability than MP-C on Vero cells at high concentrations, whereas, MP-C showed more antitumor activity on PC3 cells than MP sample. Moreover, MP-C showed a higher cell uptake than MP due to its smaller size and more negative charge. SIGNIFICANCE: Mg-phosphate ceramic can be used in this study successfully as a delivery system for cerium ions and showed a high antitumor activity, which makes it highly recommended as safe and effective cancer treatment materials.


Assuntos
Cerâmica/farmacologia , Cério/farmacologia , Compostos de Magnésio/farmacologia , Fosfatos/farmacologia , Animais , Antibacterianos/farmacologia , Antineoplásicos/farmacologia , Bacillaceae/efeitos dos fármacos , Osso e Ossos/microbiologia , Osso e Ossos/cirurgia , Sobrevivência Celular , Cério/metabolismo , Chlorocebus aethiops , Enterobacter aerogenes/efeitos dos fármacos , Humanos , Compostos de Magnésio/metabolismo , Testes de Sensibilidade Microbiana/métodos , Células PC-3 , Fosfatos/metabolismo , Pseudomonas aeruginosa/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Células Vero
6.
Astrobiology ; 20(3): 307-326, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32125196

RESUMO

The molecules feeding life's emergence are thought to have been provided through the hydrothermal interactions of convecting carbonic ocean waters with minerals comprising the early Hadean oceanic crust. Few laboratory experiments have simulated ancient hydrothermal conditions to test this conjecture. We used the JPL hydrothermal flow reactor to investigate CO2 reduction in simulated ancient alkaline convective systems over 3 days (T = 120°C, P = 100 bar, pH = 11). H2-rich hydrothermal simulant and CO2-rich ocean simulant solutions were periodically driven in 4-h cycles through synthetic mafic and ultramafic substrates and Fe>Ni sulfides. The resulting reductants included micromoles of HS- and formate accompanied possibly by micromoles of acetate and intermittent minor bursts of methane as ascertained by isotopic labeling. The formate concentrations directly correlated with the CO2 input as well as with millimoles of Mg2+ ions, whereas the acetate did not. Also, tens of micromoles of methane were drawn continuously from the reactor materials during what appeared to be the onset of serpentinization. These results support the hypothesis that formate may have been delivered directly to a branch of an emerging acetyl coenzyme-A pathway, thus obviating the need for the very first hydrogenation of CO2 to be made in a hydrothermal mound. Another feed to early metabolism could have been methane, likely mostly leached from primary CH4 present in the original Hadean crust or emanating from the mantle. That a small volume of methane was produced sporadically from the 13CO2-feed, perhaps from transient occlusions, echoes the mixed results and interpretations from other laboratories. As serpentinization and hydrothermal leaching can occur wherever an ocean convects within anhydrous olivine- and sulfide-rich crust, these results may be generalized to other wet rocky planets and moons in our solar system and beyond.


Assuntos
Fontes Hidrotermais/química , Compostos de Ferro/metabolismo , Compostos de Magnésio/metabolismo , Origem da Vida , Água do Mar/química , Silicatos/metabolismo , Acetilcoenzima A/metabolismo , Dióxido de Carbono/química , Planeta Terra , Hidrogênio/química , Compostos de Ferro/química , Compostos de Magnésio/química , Metano/química , Oceanos e Mares , Silicatos/química
7.
Transcription ; 10(4-5): 187-194, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31668122

RESUMO

Inorganic phosphate (Pi), a ubiquitous metabolite, is involved in all major biochemical pathways. We demonstrate that, in vitro, MgHPO4 (the intracellular Pi form) at physiological concentrations can exist in a metastable supersaturated dissolved state or as a precipitate. We have shown that in solution, MgHPO4 strongly stimulates exonuclease nascent transcript cleavage by RNA polymerase. We report here that MgHPO4 precipitate selectively and efficiently inhibits transcription initiation in vitro. In view of the MgHPO4 solubility and in vitro sensitivity of RNA synthesis to MgHPO4 precipitate, at physiological concentrations, MgHPO4 should cause a 50-98% inhibition of cellular RNA synthesis, thus exerting a strong regulatory action. The effects of Pi on transcription in vivo will, therefore, reflect the physical state of intracellular Pi.


Assuntos
Exonucleases/metabolismo , Fosfatos/metabolismo , RNA Mensageiro/metabolismo , Precipitação Química , RNA Polimerases Dirigidas por DNA/metabolismo , Compostos de Magnésio/metabolismo , Compostos de Magnésio/farmacologia , Fosfatos/farmacologia , Solubilidade , Transcrição Gênica/efeitos dos fármacos
8.
Enzyme Microb Technol ; 128: 26-33, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31186107

RESUMO

Detection tubes are small devices for the colorimetric enzymatic detection of cholinesterase inhibitors such as sarin, soman, VX nerve agents and substances denoted as Novichok. These detectors contain carriers in the form of pellets with immobilized cholinesterase, substrate and detection reagent. Their advantages are portability, sensitivity and simplicity, enabling fast detection of such compounds from air and water in case of a terrorist attack or war. In general, maintaining the stability of an enzyme for a longer time is very problematic; therefore, its further enhancement is required for safety and financial reasons. In this study, the stability of our patented carriers in the form of pellets with immobilized butyrylcholinesterase containing an increasing amount of the unique sorbent Neusilin® US2 was evaluated. The samples containing Neusilin maintained the stability of the immobilized enzyme for a longer time even at higher temperature and humidity than the currently commercially used carrier without Neusilin, allowing improved detection of nerve agents.


Assuntos
Compostos de Alumínio/metabolismo , Técnicas Biossensoriais/métodos , Butirilcolinesterase/metabolismo , Inibidores da Colinesterase/análise , Colorimetria/métodos , Portadores de Fármacos/química , Estabilidade Enzimática/efeitos dos fármacos , Compostos de Magnésio/metabolismo , Silicatos/metabolismo , Butirilcolinesterase/química , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo
9.
Adv Colloid Interface Sci ; 269: 219-235, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31096075

RESUMO

This article focuses on the relevance of amorphous calcium (and magnesium) phosphates in living organisms. Although crystalline calcium phosphate (CaP)-based materials are known to constitute the major inorganic constituents of human hard tissues, amorphous CaP-based structures, often in combination with magnesium, are frequently employed by Nature to build up components of our body and guarantee their proper functioning. After a brief description of amorphous calcium phosphate (ACP) formation mechanism and structure, this paper is focused on the stabilization strategies that can be used to enhance the lifetime of the poorly stable amorphous phase. The various locations of our body in which ACP (pure or in combination with Mg2+) can be found (i.e. bone, enamel, small intestine, calciprotein particles and casein micelles) are highlighted, showing how the amorphous nature of ACP is often of paramount importance for the achievement of a specific physiological function. The last section is devoted to ACP-based biomaterials, focusing on how these materials differ from their crystalline counterparts in terms of biological response.


Assuntos
Fosfatos de Cálcio/metabolismo , Materiais Dentários/química , Compostos de Magnésio/metabolismo , Fosfatos/metabolismo , Antibacterianos/química , Antibacterianos/farmacologia , Materiais Biocompatíveis/química , Osso e Ossos/química , Osso e Ossos/metabolismo , Fosfatos de Cálcio/análise , Fosfatos de Cálcio/química , Caseínas/química , Esmalte Dentário/química , Esmalte Dentário/metabolismo , Humanos , Intestino Delgado/química , Intestino Delgado/metabolismo , Micelas , Leite Humano/química
11.
ISME J ; 13(7): 1737-1749, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30867546

RESUMO

Earth's largest aquifer ecosystem resides in igneous oceanic crust, where chemosynthesis and water-rock reactions provide the carbon and energy that support an active deep biosphere. The Calvin Cycle is the predominant carbon fixation pathway in cool, oxic, crust; however, the energy and carbon metabolisms in the deep thermal basaltic aquifer are poorly understood. Anaerobic carbon fixation pathways such as the Wood-Ljungdahl pathway, which uses hydrogen (H2) and CO2, may be common in thermal aquifers since water-rock reactions can produce H2 in hydrothermal environments and bicarbonate is abundant in seawater. To test this, we reconstructed the metabolisms of eleven bacterial and archaeal metagenome-assembled genomes from an olivine biofilm obtained from a Juan de Fuca Ridge basaltic aquifer. We found that the dominant carbon fixation pathway was the Wood-Ljungdahl pathway, which was present in seven of the eight bacterial genomes. Anaerobic respiration appears to be driven by sulfate reduction, and one bacterial genome contained a complete nitrogen fixation pathway. This study reveals the potential pathways for carbon and energy flux in the deep anoxic thermal aquifer ecosystem, and suggests that ancient H2-based chemolithoautotrophy, which once dominated Earth's early biosphere, may thus remain one of the dominant metabolisms in the suboceanic aquifer today.


Assuntos
Archaea/metabolismo , Bactérias/metabolismo , Compostos de Ferro/metabolismo , Compostos de Magnésio/metabolismo , Silicatos/metabolismo , Archaea/classificação , Archaea/genética , Archaea/isolamento & purificação , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Biofilmes , Ciclo do Carbono , Ecossistema , Metabolismo Energético , Genoma Bacteriano , Água Subterrânea , Metagenoma , Fixação de Nitrogênio , Oceanos e Mares , Filogenia , Água do Mar/análise , Água do Mar/microbiologia
12.
ACS Nano ; 13(3): 2888-2900, 2019 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-30741535

RESUMO

Nucleic acid nanostructures have attracted significant interest as potential therapeutic and diagnostic platforms due to their intrinsic biocompatibility and biodegradability, structural and functional diversity, and compatibility with various chemistries for modification and stabilization. Among the fabrication approaches for such structures, the rolling circle techniques have emerged as particularly promising, producing morphologically round, flower-shaped nucleic acid particles: typically hybrid composites of long nucleic acid strands and inorganic magnesium pyrophosphate (Mg2PPi). These constructs are known to form via anisotropic nucleic acid-driven crystallization in a sequence-independent manner, rendering monodisperse and densely packed RNA or DNA-inorganic composites. However, it still remains to fully explore how flexible polymer-like RNA or DNA strands (acting as biomolecular additives) mediate the crystallization process of Mg2PPi and affect the structure and properties of the product crystals. To address this, we closely examined nanoscale details to mesoscopic features of Mg2PPi/DNA hybrid composites fabricated by two approaches, namely rolling circle amplification (RCA)-based in situ synthesis and long synthetic DNA-mediated crystallization. Similar to the DNA constructs fabricated by RCA, the rapid crystallization of Mg2PPi was retarded on a short-range order when we precipitated the crystals in the presence of presynthesized long DNA, which resulted in effective incorporation of biomolecular additives such as DNA and enzymes. These findings further provide a more feasible way to encapsulate bioactive enzymes within DNA constructs compared to in situ RCA-mediated synthesis, i.e., by not only protecting them from possible denaturation under the reaction conditions but also preventing nonselective association of proteins arising from the RCA reaction mixtures.


Assuntos
DNA/química , Difosfatos/química , Compostos de Magnésio/química , Nanoestruturas/química , Cristalização , DNA/síntese química , DNA/metabolismo , Difosfatos/metabolismo , Compostos de Magnésio/metabolismo , Estrutura Molecular , Técnicas de Amplificação de Ácido Nucleico , Tamanho da Partícula , Ribonuclease Pancreático/química , Ribonuclease Pancreático/metabolismo
13.
Biol Trace Elem Res ; 187(1): 128-136, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29679349

RESUMO

Magnesium is an element of great importance functioning because of its association with many cellular physiological functions. The magnesium content of foods is gradually decreasing due to food processing, and magnesium supplementation for healthy living has become increasingly popular. However, data is very limited on the bioavailability of various magnesium preparations. The aim of this study is to investigate the bioavailability of five different magnesium compounds (magnesium sulfate, magnesium oxide, magnesium acetyl taurate, magnesium citrate, and magnesium malate) in different tissues. Following a single dose 400 mg/70 kg magnesium administration to Sprague Dawley rats, bioavailability was evaluated by examining time-dependent absorption, tissue penetration, and the effects on the behavior of the animals. Pharmacokinetically, the area under the curve calculation is highest in the magnesium malate. The magnesium acetyl taurate was found to have the second highest area under the curve calculation. Magnesium acetyl taurate was rapidly absorbed, able to pass through to the brain easily, had the highest tissue concentration level in the brain, and was found to be associated with decreased anxiety indicators. Magnesium malate levels remained high for an extended period of time in the serum. The commonly prescribed dietary supplements magnesium oxide and magnesium citrate had the lowest bioavailability when compared to our control group. More research is needed to investigate the bioavailability of magnesium malate and acetyl taurate compounds and their effects in specific tissues and on behavior.


Assuntos
Compostos de Magnésio/metabolismo , Compostos de Magnésio/farmacocinética , Animais , Área Sob a Curva , Disponibilidade Biológica , Suplementos Nutricionais , Compostos de Magnésio/administração & dosagem , Masculino , Ratos , Ratos Sprague-Dawley , Fatores de Tempo
14.
AAPS PharmSciTech ; 19(2): 681-692, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28971441

RESUMO

Burst drug release is often considered a negative phenomenon resulting in unexpected toxicity or tissue irritation. Optimal release of a highly soluble active pharmaceutical ingredient (API) from hypromellose (HPMC) matrices is technologically impossible; therefore, a combination of polymers is required for burst effect reduction. Promising variant could be seen in combination of HPMC and insoluble Eudragits® as water dispersions. These can be applied only on API/insoluble filler mixture as over-wetting prevention. The main hurdle is a limited water absorption capacity (WAC) of filler. Therefore, the object of this study was to investigate the dissolution behavior of levetiracetam from HPMC/Eudragit®NE matrices using magnesium aluminometasilicate (Neusilin® US2) as filler with excellent WAC. Part of this study was also to assess influence of thermal treatment on quality parameters of matrices. The use of Neusilin® allowed the application of Eudragit® dispersion to API/Neusilin® mixture in one step during high-shear wet granulation. HPMC was added extragranularly. Obtained matrices were investigated for qualitative characteristics, NMR solid-state spectroscopy (ssNMR), gel layer dynamic parameters, SEM, and principal component analysis (PCA). Decrease in burst effect (max. of 33.6%) and dissolution rate, increase in fitting to zero-order kinetics, and paradoxical reduction in gel layer thickness were observed with rising Eudragit® NE concentration. The explanation was done by ssNMR, which clearly showed a significant reduction of the API particle size (150-500 nm) in granules as effect of surfactant present in dispersion in dependence on Eudragit®NE amount. This change in API particle size resulted in a significantly larger interface between these two entities. Based on ANOVA and PCA, thermal treatment was not revealed as a useful procedure for this system.


Assuntos
Compostos de Alumínio/química , Compostos de Alumínio/metabolismo , Compostos de Magnésio/química , Compostos de Magnésio/metabolismo , Espectroscopia de Ressonância Magnética/métodos , Ácidos Polimetacrílicos/química , Ácidos Polimetacrílicos/metabolismo , Silicatos/química , Silicatos/metabolismo , Administração Oral , Compostos de Alumínio/administração & dosagem , Preparações de Ação Retardada/administração & dosagem , Preparações de Ação Retardada/química , Preparações de Ação Retardada/metabolismo , Liberação Controlada de Fármacos , Excipientes/química , Géis , Compostos de Magnésio/administração & dosagem , Tamanho da Partícula , Ácidos Polimetacrílicos/administração & dosagem , Silicatos/administração & dosagem , Solubilidade
15.
Biomol NMR Assign ; 11(2): 251-256, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28866776

RESUMO

Human phosphoglycerate kinase (PGK) is an energy generating glycolytic enzyme that catalyses the transfer of a phosphoryl group from 1,3-bisphosphoglycerate (BPG) to ADP producing 3-phosphoglycerate (3PG) and ATP. PGK is composed of two α/ß Rossmann-fold domains linked by a central α-helix and the active site is located in the cleft formed between the N-domain which binds BPG or 3PG, and the C-domain which binds the nucleotides ADP or ATP. Domain closure is required to bring the two substrates into close proximity for phosphoryl transfer to occur, however previous structural studies involving a range of native substrates and substrate analogues only yielded open or partly closed PGK complexes. X-ray crystallography using magnesium trifluoride (MgF3-) as a isoelectronic and near-isosteric mimic of the transferring phosphoryl group (PO3-), together with 3PG and ADP has been successful in trapping human PGK in a fully closed transition state analogue (TSA) complex. In this work we report the 1H, 15N and 13C backbone resonance assignments of human PGK in the solution conformation of the fully closed PGK:3PG:MgF3:ADP TSA complex. Assignments were obtained by heteronuclear multidimensional NMR spectroscopy. In total, 97% of all backbone resonances were assigned in the complex, with 385 out of a possible 399 residues assigned in the 1H-15N TROSY spectrum. Prediction of solution secondary structure from a chemical shift analysis using the TALOS-N webserver is in good agreement with the published X-ray crystal structure of this complex.


Assuntos
Difosfato de Adenosina/metabolismo , Fluoretos/metabolismo , Gliceraldeído 3-Fosfato/metabolismo , Compostos de Magnésio/metabolismo , Ressonância Magnética Nuclear Biomolecular , Fosfoglicerato Quinase/química , Fosfoglicerato Quinase/metabolismo , Humanos , Modelos Moleculares , Ligação Proteica , Conformação Proteica em alfa-Hélice
16.
Top Curr Chem (Cham) ; 375(2): 36, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28299727

RESUMO

The phosphoryl group, PO3-, is the dynamic structural unit in the biological chemistry of phosphorus. Its transfer from a donor to an acceptor atom, with oxygen much more prevalent than nitrogen, carbon, or sulfur, is at the core of a great majority of enzyme-catalyzed reactions involving phosphate esters, anhydrides, amidates, and phosphorothioates. The serendipitous discovery that the phosphoryl group could be labeled by "nuclear mutation," by substitution of PO3- by MgF3- or AlF4-, has underpinned the application of metal fluoride (MF x ) complexes to mimic transition states for enzymatic phosphoryl transfer reactions, with sufficient stability for experimental analysis. Protein crystallography in the solid state and 19F NMR in solution have enabled direct observation of ternary and quaternary protein complexes embracing MF x transition state models with precision. These studies have underpinned a radically new mechanistic approach to enzyme catalysis for a huge range of phosphoryl transfer processes, as varied as kinases, phosphatases, phosphomutases, and phosphohydrolases. The results, without exception, have endorsed trigonal bipyramidal geometry (tbp) for concerted, "in-line" stereochemistry of phosphoryl transfer. QM computations have established the validity of tbp MF x complexes as reliable models for true transition states, delivering similar bond lengths, coordination to essential metal ions, and virtually identical hydrogen bond networks. The emergence of protein control of reactant orbital overlap between bond-forming species within enzyme transition states is a new challenging theme for wider exploration.


Assuntos
Fluoretos/metabolismo , Fosfinas/metabolismo , Monoéster Fosfórico Hidrolases/metabolismo , Fosfotransferases (Fosfomutases)/metabolismo , Fosfotransferases/metabolismo , Compostos de Alumínio/química , Compostos de Alumínio/metabolismo , Fluoretos/química , Compostos de Magnésio/química , Compostos de Magnésio/metabolismo , Estrutura Molecular , Fosfinas/química , Monoéster Fosfórico Hidrolases/química , Fosfotransferases/química , Fosfotransferases (Fosfomutases)/química
17.
J Mol Biol ; 428(15): 3043-57, 2016 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-27363609

RESUMO

The GTP hydrolysis activities of Rho GTPases are stimulated by GTPase-activating proteins (GAPs), which contain a RhoGAP domain equipped with a characteristic arginine finger and an auxiliary asparagine for catalysis. However, the auxiliary asparagine is missing in the RhoGAP domain of Myo9b (Myo9b-RhoGAP), a unique motorized RhoGAP that specifically targets RhoA for controlling cell motility. Here, we determined the structure of Myo9b-RhoGAP in complex with GDP-bound RhoA and magnesium fluoride. Unexpectedly, Myo9b-RhoGAP contains two arginine fingers at its catalytic site. The first arginine finger resembles the one within the canonical RhoGAP domains and inserts into the nucleotide-binding pocket of RhoA, whereas the second arginine finger anchors the Switch I loop of RhoA and interacts with the nucleotide, stabilizing the transition state of GTP hydrolysis and compensating for the lack of the asparagine. Mutating either of the two arginine fingers impaired the catalytic activity of Myo9b-RhoGAP and affected the Myo9b-mediated cell migration. Our data indicate that Myo9b-RhoGAP accelerates RhoA GTP hydrolysis by a previously unknown dual-arginine-finger mechanism, which may be shared by other noncanonical RhoGAP domains lacking the auxiliary asparagine.


Assuntos
Arginina/metabolismo , Proteínas Ativadoras de GTPase/metabolismo , Miosinas/metabolismo , Proteína rhoA de Ligação ao GTP/metabolismo , Catálise , Domínio Catalítico/fisiologia , Fluoretos/metabolismo , Guanosina Trifosfato/metabolismo , Humanos , Hidrólise , Compostos de Magnésio/metabolismo , Ligação Proteica/fisiologia , Proteínas rho de Ligação ao GTP/metabolismo
18.
J Pharm Sci ; 105(2): 766-772, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26869429

RESUMO

The magnesium pyrophosphate particle (MgPP) is a unique and safe carrier that is prepared by simply mixing magnesium chloride and sodium pyrophosphate. In this study, we investigated whether MgPP can be used to deliver nucleic acid-based adjuvants to immune cells. Polyriboinosinic-polyribocytidylic acid (polyI:C), a ligand for toll-like receptor 3, was selected as a model nucleic acid-based adjuvant. PolyI:C-loaded MgPP (polyI:C-MgPP) was prepared by adding polyI:C during the MgPP preparation process. Efficient loading of polyI:C into MgPP was confirmed by measuring the absorbance at 260 nm after disruption of polyI:C-MgPP by ethylenediaminetetraacetic acid. Scanning electron microscopy revealed that both MgPP and polyI:C-MgPP had a unique sponge-like shape with a diameter of approximately 1 µm. PolyI:C-MgPP was more efficiently taken up by toll-like receptor 3-positive RAW264.7 cells than naked polyI:C, and its uptake stimulated increased tumor necrosis factor-α production. When the presentation of ovalbumin (OVA), a model antigen, was evaluated after the addition of OVA along with naked polyI:C or polyI:C-MgPP to mouse dendritic DC2.4 cells, polyI:C-MgPP substantially increased OVA presentation. These results indicate that MgPP is a useful delivery vehicle for polyI:C and that polyI:C-MgPP is an effective immune cell adjuvant.


Assuntos
Adjuvantes Imunológicos/administração & dosagem , Células Dendríticas/efeitos dos fármacos , Difosfatos/administração & dosagem , Compostos de Magnésio/administração & dosagem , Microesferas , Polinucleotídeos/administração & dosagem , Adjuvantes Imunológicos/metabolismo , Animais , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Difosfatos/metabolismo , Compostos de Magnésio/metabolismo , Camundongos , Poli I-C , Polinucleotídeos/metabolismo , Receptor 3 Toll-Like/imunologia , Receptor 3 Toll-Like/metabolismo
19.
Poult Sci ; 95(4): 878-85, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26787924

RESUMO

The current study was conducted to investigate the effect of zinc (Zn) bearing palygorskite (ZnPal) inclusion on the growth performance, mineral content, meat quality, and antioxidant status of broilers. A total of 240 one-day-old Arbor Acres broiler chicks were randomly allocated into 5 dietary treatments with 6 replicates of 8 chicks. Broilers in the 5 treatments were fed a basal diet supplemented with 0, 20, 40, 60, and 80 mg/kg Zn diet in the form of ZnPal for 42 d, respectively. Birds exhibited similar average daily gain (ADG), average daily feed intake (ADFI), and feed/gain ratio (F:G) among groups during the 42-day study (P>0.05). ZnPal supplementation linearly increased iron (Fe) (P=0.031) and magnesium (Mg) (P=0.002) content in the pectoralis major muscle. Similarly, the inclusion of ZnPal tended to increase Zn content in the thigh (P=0.072) and linearly increase Zn content in the pectoralis major muscle (P=0.055). The concentration of copper (Cu) in the thigh was linearly decreased by ZnPal inclusion (P=0.011). Meanwhile, a quadratic trend for reduced Cu content was observed in the pectoralis major muscle (P=0.074) and thigh (P=0.082), respectively. The supplementation of ZnPal linearly reduced cooking loss in the pectoralis major muscle (P=0.013), and linearly (P=0.029) and quadratically (P=0.034) decreased cooking loss in the thigh. Malondialdehyde (MDA) concentration in the thigh was linearly (P=0.020) and quadratically (P=0.017) reduced by ZnPal inclusion. Additionally, ZnPal supplementation tended to linearly enhance total antioxidant capacity (T-AOC) activity of the pectoralis major muscle (P=0.083). The results obtained in the current study indicated that ZnPal inclusion could alter muscular mineral accumulation, improve meat quality, and enhance the muscular antioxidant capacity of broilers, and Zn supplementation in the form of ZnPal at the dosage of 20 mg/kg would be sufficient in improving meat quality and muscular oxidative status.


Assuntos
Antioxidantes/metabolismo , Galinhas/fisiologia , Compostos de Magnésio/metabolismo , Carne/análise , Minerais/metabolismo , Compostos de Silício/metabolismo , Zinco/metabolismo , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal/efeitos dos fármacos , Animais , Galinhas/crescimento & desenvolvimento , Dieta/veterinária , Suplementos Nutricionais/análise , Feminino , Compostos de Magnésio/administração & dosagem , Masculino , Distribuição Aleatória , Compostos de Silício/administração & dosagem , Zinco/administração & dosagem
20.
Urologiia ; (3): 19-25, 2016 Aug.
Artigo em Russo | MEDLINE | ID: mdl-28247625

RESUMO

This paper focuses on developing and implementing a method of quantitative mineralogical analysis of urinary stones based on powder diffraction data analysis using 4 Topas (Bruker) software. Mineralogical composition of 100 urinary stones from urolithiasis patients living in Ivanovo region was examined. More than 70% of stones consisted of calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD), and their mixtures with hydroxylapatite. Forty four percent of urinary stones consisted of one component (COM, uric acid (UA) or, less frequently, hydroxyapatite (HA); 56% of urinary stones comprised two, three or four components. The most common mineral was COM (more than 70% of cases), the rarest were calcium oxalate trihydrate (CT), brushite and newberrite. The most common combinations of minerals in mixed stones were COM+HA, COM+COD and COM+COD+HA. The texture, the surface composition and its changes in the course of chemolysis in different types of stones were examined using scanning electron microscopy (SEM) and X-ray microanalysis (XRM). Implications for using analytical chemical and physical techniques for the diagnosis and treatment of urolithiasis were discussed.


Assuntos
Oxalato de Cálcio/metabolismo , Fosfatos de Cálcio/metabolismo , Durapatita/metabolismo , Compostos de Magnésio/metabolismo , Fosfatos/metabolismo , Ácido Úrico/metabolismo , Cálculos Urinários/metabolismo , Feminino , Humanos , Masculino , Federação Russa/epidemiologia , Cálculos Urinários/epidemiologia
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