RESUMO

This work introduces a novel way to obtain catalytically competent oxyferryl species for two different dye-decolorizing peroxidases (DyPs) in the absence of H2O2 or any other peroxide by simply applying a reductive electrochemical potential under aerobic conditions. UV-vis and resonance Raman spectroscopies show that this method yields long-lived compounds II and I for the DyPs from Bacillus subtilis (BsDyP; Class I) and Pseudomonas putida (PpDyP; Class P), respectively. Both electrochemically generated high valent intermediates are able to oxidize ABTS at both acidic and alkaline pH. Interestingly, the electrocatalytic efficiencies obtained at pH 7.6 are very similar to the values recorded for regular catalytic ABTS/H2O2 assays at the optimal pH of the enzymes, ca. 3.7. These findings pave the way for the design of DyP-based electrocatalytic reactors operable in an extended pH range without the need of harmful reagents such as H2O2.

Assuntos

Corantes/química , Peroxidases/química , Peróxidos/química , Bacillus subtilis/química , Catálise/efeitos dos fármacos , Corantes/farmacologia , Peróxido de Hidrogênio/química , Concentração de Íons de Hidrogênio , Oxirredução/efeitos dos fármacos , Pseudomonas putida/química , Análise Espectral Raman

RESUMO

This work explores the effect of two metallic wastes (mining wastes, MW; fly ashes, FA) and micro-aeration (MA) on the anaerobic digestion of wastewater which is rich in sulfate and sulfide. Two initial COD concentrations (5,000 and 10,000 mg/L) were studied under both conditions in batch systems at 35 °C, with a fixed COD/SO42- ratio = 10, with 100 mg/L of S2-. It was observed that the use of MW and FA in the assays with an initial COD concentration of 10,000 mg/L resulted in a simultaneous increase in COD removal, sulfate removal, sulfide removal and methane generation, while MA only improved the COD and sulfide removals in comparison with the control system. On the contrary, the use of MW, FA or MA in systems with initial COD concentrations equal to or lower than 5,000 mg/L did not show any improvement with respect to the control system in terms of COD removal, sulfate removal or methane generation, with only sulfide removal being positively affected by MW and FA.

Assuntos

Metais/farmacologia , Metano/biossíntese , Sulfatos/isolamento & purificação , Sulfetos/isolamento & purificação , Águas Residuárias/química , Anaerobiose/efeitos dos fármacos , Reatores Biológicos , Catálise/efeitos dos fármacos , Resíduos Industriais , Mineração , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/isolamento & purificação , Poluentes Químicos da Água/farmacologia , Purificação da Água/métodos

RESUMO

Chitosan partially functionalized with aldehyde groups was used for enzyme immobilization, favoring first the enzyme adsorption through its amino groups and then the covalent bonding of the adsorbed catalyst through the aldehyde groups of the support. Using this strategy, immobilized A. oryzae ß-galactosidase had a better performance than when only the aldehyde groups were used. The performance was further improved by modifying the support aldehyde group density to 200 µmoles⋅g-1. The biocatalyst under optimized immobilization conditions had 2951 IU⋅g-1 and half-life of 46.3 min at 60 °C, while its agarose counterpart had 2294 IU⋅g-1 and half-life of 59.5 min. Both biocatalysts were applied in galacto-oligosaccharide synthesis. After 10 sequential batches, the cumulative productivity (gGOS⋅h-1ˑgprotein-1) obtained with the chitosan and the agarose biocatalysts were 4.7 and 4.0 times the value when soluble enzyme was used respectively. This methodology had not been reported previously with chitosan, showing the high versatility of this low cost carrier and its high potential for enzyme immobilization.

Assuntos

Quitosana/metabolismo , Enzimas Imobilizadas/metabolismo , beta-Galactosidase/metabolismo , Adsorção/efeitos dos fármacos , Aldeídos/metabolismo , Catálise/efeitos dos fármacos , Sefarose/metabolismo

RESUMO

The objectives of this study were to determine the kinetic parameters of purified recombinant BlaMab and BlaMmas by spectrophotometry, analyze the genetic environment of the blaMab and blaMmas genes in both species by polymerase chain reaction and sequencing, furthermore, in silico models of both enzymes in complex with imipenem were obtained by modeling tools. Our results showed that BlaMab and BlaMmas have a similar hydrolysis behavior, displaying high catalytic efficiencies toward penams, cephalothin, and nitrocefin; none of the enzymes are well inhibited by clavulanate. BlaMmas hydrolyzes imipenem at higher efficiency than cefotaxime and aztreonam. BlaMab and BlaMmas showed that their closest structural homologs are KPC-2 and SFC-1, which correlate to the mild carbapenemase activity toward imipenem observed at least for BlaMmas. They also seem to differ from other class A ß-lactamases by the presence of a more flexible Ω loop, which could impact in the hydrolysis efficiency against some antibiotics. A -35 consensus sequence (TCGACA) and embedded at the 3' end of MAB_2874, which may constitute the blaMab and blaMmas promoter. Our results suggest that the resistance mechanisms in fast-growing mycobacteria could be probably evolving toward the production of ß-lactamases that have improved catalytic efficiencies against some of the drugs commonly used for the treatment of mycobacterial infections, endangering the use of important drugs like the carbapenems.

Assuntos

Mycobacterium/genética , beta-Lactamases/genética , Antibacterianos/farmacologia , Catálise/efeitos dos fármacos , Sequência Consenso/genética , Farmacorresistência Bacteriana/efeitos dos fármacos , Farmacorresistência Bacteriana/genética , Hidrólise/efeitos dos fármacos , Cinética , Testes de Sensibilidade Microbiana/métodos , Mycobacterium/efeitos dos fármacos , Infecções por Mycobacterium/tratamento farmacológico , Infecções por Mycobacterium/microbiologia , Regiões Promotoras Genéticas/efeitos dos fármacos , Regiões Promotoras Genéticas/genética

RESUMO

Crude glycerol, also known as glycerin, is the main byproduct of the biodiesel industry. It has been estimated that up to 40,000 tons of glycerin will be produced each year by 2020. This study evaluated the value-added use of crude glycerol derived from soybean biodiesel preparation as a carbon source for heterologous protein production using the yeast Pichia pastoris. Eleven glycerin samples were obtained by methanolysis of soybean oil using different acids or bases as catalysts. Cell growth experiments showed that crude glycerol containing either potassium or sodium hydroxide resulted in 1.5-2 times higher final cell densities when compared to glycerol P.A. Finally, crude glycerol containing sodium hydroxide was successfully utilized for constitutive heterologous α-amylase production in P. pastoris. This study demonstrated that crude glycerol without any purification steps may be directly used as carbon source for protein production in P. pastoris.

Assuntos

Biocombustíveis , Carbono/farmacologia , Glicerol/farmacologia , Pichia/metabolismo , Óleo de Soja/química , alfa-Amilases/biossíntese , Aerobiose/efeitos dos fármacos , Bacillus subtilis/efeitos dos fármacos , Bacillus subtilis/enzimologia , Catálise/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Fermentação/efeitos dos fármacos , Metanol/farmacologia , Pichia/efeitos dos fármacos , Pichia/crescimento & desenvolvimento

RESUMO

Age-related diseases are associated with increased production of reactive oxygen and carbonyl species such as methylglyoxal. Aminoacetone, a putative threonine catabolite, is reportedly known to undergo metal-catalyzed oxidation to methylglyoxal, NH4(+) ion, and H2O2 coupled with (i) permeabilization of rat liver mitochondria, and (ii) apoptosis of insulin-producing cells. Oxidation of aminoacetone to methylglyoxal is now shown to be accelerated by ferricytochrome c, a reaction initiated by one-electron reduction of ferricytochrome c by aminoacetone without amino acid modifications. The participation of O2(•-) and HO (•) radical intermediates is demonstrated by the inhibitory effect of added superoxide dismutase and Electron Paramagnetic Resonance spin-trapping experiments with 5,5'-dimethyl-1-pyrroline-N-oxide. We hypothesize that two consecutive one-electron transfers from aminoacetone (E0 values = -0.51 and -1.0 V) to ferricytochrome c (E0 = 0.26 V) may lead to aminoacetone enoyl radical and, subsequently, imine aminoacetone, whose hydrolysis yields methylglyoxal and NH4(+) ion. In the presence of oxygen, aminoacetone enoyl and O2(•-) radicals propagate aminoacetone oxidation to methylglyoxal and H2O2. These data endorse the hypothesis that aminoacetone, putatively accumulated in diabetes, may directly reduce ferricyt c yielding methylglyoxal and free radicals, thereby triggering redox imbalance and adverse mitochondrial responses.

Assuntos

Acetona/análogos & derivados , Citocromos c/metabolismo , Carbonilação Proteica , Aldeído Pirúvico/metabolismo , Estresse Fisiológico , Acetona/metabolismo , Aerobiose/efeitos dos fármacos , Animais , Catálise/efeitos dos fármacos , Dicroísmo Circular , Simulação por Computador , Cobre/farmacologia , Citocromos c/química , Espectroscopia de Ressonância de Spin Eletrônica , Radicais Livres/metabolismo , Heme/metabolismo , Cavalos , Íons , Ferro/farmacologia , Oxirredução/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Carbonilação Proteica/efeitos dos fármacos , Ratos , Espectrofotometria Ultravioleta , Estresse Fisiológico/efeitos dos fármacos , Temperatura

RESUMO

In the work presented here, a photocatalytic system using titanium Degussa P-25 in suspension was used to evaluate the degradation of 20mg L(-1) of antibiotic oxolinic acid (OA). The effects of catalyst load (0.2-1.5 g L(-1)) and pH (7.5-11) were evaluated and optimized using the surface response methodology and the Pareto diagram. In the range of variables studied, low pH values and 1.0 g L(-1) of TiO(2) favoured the efficiency of the process. Under optimal conditions the evolution of the substrate, chemical oxygen demand, dissolved organic carbon, toxicity and antimicrobial activity on Escherichia coli cultures were evaluated. The results indicate that, under optimal conditions, after 30 min, the TiO(2) photocatalytic system is able to eliminate both the substrate and the antimicrobial activity, and to reduce the toxicity of the solution by 60%. However, at the same time, ∼53% of both initial DOC and COD remain in solution. Thus, the photocatalytical system is able to transform the target compound into more oxidized by-products without antimicrobial activity and with a low toxicity. The study of OA by-products using liquid chromatography coupled with mass spectrometry, as well as the evaluation of OA degradation in acetonitrile media as solvent or in the presence of isopropanol and iodide suggest that the reaction is initiated by the photo-Kolbe reaction. Adsorption isotherm experiments in the dark indicated that under pH 7.5, adsorption corresponded to the Langmuir adsorption model, indicating the dependence of the reaction on an initial adsorption step.

Assuntos

Antibacterianos/química , Luz , Ácido Oxolínico/química , Titânio/química , 2-Propanol/química , Acetonitrilas/química , Adsorção/efeitos dos fármacos , Adsorção/efeitos da radiação , Antibacterianos/farmacologia , Antibacterianos/toxicidade , Catálise/efeitos dos fármacos , Catálise/efeitos da radiação , Cromatografia Líquida de Alta Pressão , Escherichia coli/efeitos dos fármacos , Escherichia coli/efeitos da radiação , Concentração de Íons de Hidrogênio/efeitos dos fármacos , Concentração de Íons de Hidrogênio/efeitos da radiação , Espectrometria de Massas , Testes de Sensibilidade Microbiana , Ácido Oxolínico/farmacologia , Ácido Oxolínico/toxicidade , Fotólise/efeitos dos fármacos , Fotólise/efeitos da radiação , Iodeto de Potássio/química , Soluções , Solventes/química , Suspensões , Temperatura

RESUMO

A class of drugs in use for treating type II diabetes mellitus (T2D), typified by the pseudotetrasaccharide acarbose, act by inhibiting the alpha-glucosidase activity present in pancreatic secretions and in the brush border of the small intestine. Herein, we report the synthesis of a series of 4-substituted 1,2,3-triazoles conjugated with sugars, including D-xylose, D-galactose, D-allose, and D-ribose. Compounds were screened for alpha-glucosidase inhibitory activity using yeast maltase (MAL12) as a model enzyme. Methyl-2,3-O-isopropylidene-beta-D-ribofuranosides, such as the 4-(1-cyclohexenyl)-1,2,3-triazole derivative, were among the most active compounds, showing up to 25-fold higher inhibitory potency than the complex oligosaccharide acarbose. Docking studies on a MAL12 homology model disclosed a binding mode consistent with a transition-state-mimicking mechanism. Finally, the actual pharmacological potential of this triazole series was demonstrated by the reduction of postprandial blood glucose levels in normal rats. These compounds could represent new chemical scaffolds for developing novel drugs against T2D.

Assuntos

Carboidratos/química , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacologia , Inibidores de Glicosídeo Hidrolases , Triazóis/química , Sequência de Aminoácidos , Sítios de Ligação , Sequência de Carboidratos , Catálise/efeitos dos fármacos , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/metabolismo , Proteínas Fúngicas/antagonistas & inibidores , Proteínas Fúngicas/química , Proteínas Fúngicas/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Estrutura Molecular , Ligação Proteica , Conformação Proteica , Estrutura Terciária de Proteína , Homologia de Sequência de Aminoácidos , Relação Estrutura-Atividade , Leveduras/enzimologia , Leveduras/genética , alfa-Glucosidases/química , alfa-Glucosidases/metabolismo

RESUMO

Serine proteinases from three strains of Sitophilus zeamais (Coleoptera: Curculionidae), one susceptible and two resistant to insecticides--one exhibiting fitness cost (resistant cost strain) and the other lacking it (resistant no-cost strain), were partially purified using an aprotinin-agarose affinity column providing purification factors ranging from 36.5 to 51.2%, with yields between 10 and 15% and activity between 529 and 875 microM/min/mg protein with the substrate N-alpha-benzoyl-L-Arg-p-nitroanilide (L-BApNA). SDS-PAGE of the purified fraction revealed a 56,000 Da molecular mass band in all strains and a 70,000 Da band more visible in the resistant no-cost strain. The purified proteinases from all strains were inhibited by phenylmethyl sulphonyl fluoride (PMSF), N-alpha-tosyl-L-lysine chloromethyl ketone (TLCK), aprotinin, benzamidine and soybean trypsin inhibitor (SBTI) characterizing them as trypsin-like serine proteinases. Trypsin-like proteinases from the resistant strains exhibited higher affinity for L-BApNA. The resistant no-cost strain exhibited V(max)-values 1.5- and 1.7-fold higher than the susceptible and resistance cost strains, respectively. A similar trend was also observed when using N-alpha-p-tosyl-L-Arg methyl ester (L-TAME) as substrate. These results provide support to the hypothesis that the enhanced serine proteinase activity may be playing a role in mitigating physiological costs associated with the maintenance of insecticide resistance mechanisms in some maize weevil strains.

Assuntos

Besouros/enzimologia , Proteínas de Insetos/metabolismo , Resistência a Inseticidas , Inseticidas/toxicidade , Serina Proteases/metabolismo , Zea mays/parasitologia , Animais , Benzoilarginina Nitroanilida/metabolismo , Catálise/efeitos dos fármacos , Besouros/classificação , Eletroforese em Gel de Poliacrilamida , Concentração de Íons de Hidrogênio , Proteínas de Insetos/isolamento & purificação , Cinética , Fluoreto de Fenilmetilsulfonil/farmacologia , Inibidores de Proteases/farmacologia , Serina Proteases/isolamento & purificação , Especificidade da Espécie , Especificidade por Substrato , Temperatura , Tripsina/isolamento & purificação , Tripsina/metabolismo

RESUMO

The preparation of N-sulfonyl-1,2,3,4-tetrahydroisoquinolines, N-sulfonyl-2,3,4,5-tetrahydro-1H-2-benzazepines and N-sulfonyl-1,2,3,4,5,6-hexahydrobenzazocine was catalyzed by a Preyssler heteropolyacid, H(14)[NaP(5)W(30)O(110)], (PA), supported on silica (PASiO(2)40) with excellent yields by means of the Pictet-Spengler reaction of N-aralkylsulfonamides with s-trioxane. The reactions proceed with 0.5 mol% of silica-supported catalyst in toluene at 70°C. The catalyst can be recycled without appreciable loss of the catalytic activity.

Assuntos

Ácidos/farmacologia , Compostos Heterocíclicos/síntese química , Compostos de Enxofre/síntese química , Tetra-Hidroisoquinolinas/química , Tetra-Hidroisoquinolinas/síntese química , Ácidos/química , Catálise/efeitos dos fármacos , Química Orgânica/métodos , Química Farmacêutica/métodos , Reutilização de Equipamento , Compostos Heterocíclicos/química , Modelos Biológicos , Compostos de Enxofre/química