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1.
Food Chem ; 358: 129900, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33933980

RESUMO

In this work, a syringe needle-based integrated method was designed for the detection of biogenic amines (BAs) in raw meat samples. Based on a sequential process, the needle-based sampling, micro liquid-phase extraction and peroxidase-like catalysis were adopted for the sample collection, target analytes extraction and colorimetric analysis, respectively. The proposed method exhibited high selectivity towards BAs (the total amount of histamine, putrescine and cadaverine was utilized to present the level of BAs), where the linear range is 5-50 µM and 50-1000 µM, and the limit of detection is 1.52 µM. Specifically, the whole process could be completed in a single syringe needle. In addition, due to the minimized sampling, the change of BAs levels with time in different area of real samples (fish) can be conveniently investigated. This method has the advantages of simplicity, low cost, high sensitivity and selectivity, endowing it a promising candidate for food analysis.


Assuntos
Aminas Biogênicas/análise , Colorimetria/métodos , Análise de Alimentos/instrumentação , Carne/análise , Amina Oxidase (contendo Cobre)/química , Animais , Cadaverina/análise , Catálise , Colorimetria/instrumentação , Produtos Pesqueiros/análise , Análise de Alimentos/métodos , Armazenamento de Alimentos , Histamina/análise , Microextração em Fase Líquida , Nanopartículas Metálicas/química , Agulhas , Peroxidase/química , Carne de Porco/análise , Putrescina/análise , Compostos de Estanho/química
2.
Int J Mol Sci ; 22(5)2021 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-33807844

RESUMO

We aim to clarify the ligninolytic capabilities of dye-decolorizing peroxidases (DyPs) from bacteria and fungi, compared to fungal lignin peroxidase (LiP) and versatile peroxidase (VP). With this purpose, DyPs from Amycolatopsis sp., Thermomonospora curvata, and Auricularia auricula-judae, VP from Pleurotus eryngii, and LiP from Phanerochaete chrysosporium were produced, and their kinetic constants and reduction potentials determined. Sharp differences were found in the oxidation of nonphenolic simple (veratryl alcohol, VA) and dimeric (veratrylglycerol-ß- guaiacyl ether, VGE) lignin model compounds, with LiP showing the highest catalytic efficiencies (around 15 and 200 s-1·mM-1 for VGE and VA, respectively), while the efficiency of the A. auricula-judae DyP was 1-3 orders of magnitude lower, and no activity was detected with the bacterial DyPs. VP and LiP also showed the highest reduction potential (1.28-1.33 V) in the rate-limiting step of the catalytic cycle (i.e., compound-II reduction to resting enzyme), estimated by stopped-flow measurements at the equilibrium, while the T. curvata DyP showed the lowest value (1.23 V). We conclude that, when using realistic enzyme doses, only fungal LiP and VP, and in much lower extent fungal DyP, oxidize nonphenolic aromatics and, therefore, have the capability to act on the main moiety of the native lignin macromolecule.


Assuntos
Catalase/química , Corantes/química , Proteínas Fúngicas/química , Fungos/enzimologia , Lignina/química , Peroxidase/química
3.
Carbohydr Polym ; 258: 117691, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33593564

RESUMO

The aim of the present study is to evaluate the potential of chitosan and chitosan nanoparticles (ChNPs) in enhancing the growth and yield of finger millet under greenhouse condition. Foliar application of ChNPs significantly enhanced the growth, yield and mineral content (Fe, Zn, Mn, P, Ca, Mg) when compared to the chitosan and untreated control. ChNPs also induced several defense related enzymes (chitinase, ß-1,3 glucanase, chitosanase, protease inhibitors, peroxidase, polyphenol oxidase) in leaves of finger millet plants their by enhancing the innate immune response. This quantitative difference in defense enzymes was also detected qualitatively on polyacrylamide gels. Our results suggest that ChNPs application can be used as an ecofriendly approach to enhance yield and mineral content in finger millet for sustainable production.


Assuntos
Quitosana/química , Eleusine/efeitos dos fármacos , Imunidade Inata/efeitos dos fármacos , Nanopartículas/química , Folhas de Planta/efeitos dos fármacos , Catecol Oxidase/química , Quitinases/química , Eleusine/imunologia , Glicosídeo Hidrolases/química , Concentração de Íons de Hidrogênio , Peroxidase/química , Doenças das Plantas/imunologia , Brotos de Planta/metabolismo , Inibidores de Proteases/química , Sementes/metabolismo
4.
J Agric Food Chem ; 69(3): 1049-1056, 2021 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-33428421

RESUMO

In situ H2O2 generation systems are efficient for H2O2-dependent biocatalytic oxidation reactions. Here, we report that lytic polysaccharide monooxygenases (LPMOs), copper-dependent polysaccharide monooxygenases, can efficiently supply H2O2 in situ to dye-decolorizing peroxidases (DyPs) using substrate gallic acid (GA) for chitosan functionalization. The maximum grafting ratio induced by the cascade reaction was significantly higher than that achieved by a reaction with initial exogenous H2O2. The maximum grafting ratio was obtained with 12 g/L GA, 5.6 mg/L DyP, 20-30 mg/L LPMO, and pH 4.5-5.0. UV-vis, Fourier transform infrared (FT-IR), and nuclear magnetic resonance (1H NMR) spectroscopy confirmed GA grafting onto chitosan. X-ray diffraction (XRD) analysis and thermogravimetric analysis (TGA) indicated that GA-chitosan conjugates had lower thermal stability and crystallinity than chitosan. The GA-chitosan conjugates had significantly higher antioxidant activity than chitosan. This study supplies a green and high-efficiency approach to achieve an enzymatic cascade reaction for chitosan functionalization and has potential applications in H2O2-dependent biocatalytic oxidation reactions.


Assuntos
Quitosana/química , Proteínas Fúngicas/química , Oxigenases de Função Mista/química , Peroxidase/química , Antioxidantes/química , Antioxidantes/metabolismo , Quitosana/metabolismo , Temperatura Alta , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/metabolismo , Oxigenases de Função Mista/genética , Oxigenases de Função Mista/metabolismo , Oxirredução , Peroxidase/genética , Peroxidase/metabolismo , Pleurotus/enzimologia , Pleurotus/genética , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
5.
Adv Mater ; 33(8): e2005477, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33475193

RESUMO

Besides the pandemic caused by the coronavirus outbreak, many other pathogenic microbes also pose a devastating threat to human health, for instance, pathogenic bacteria. Due to the lack of broad-spectrum antibiotics, it is urgent to develop nonantibiotic strategies to fight bacteria. Herein, inspired by the localized "capture and killing" action of bacteriophages, a virus-like peroxidase-mimic (V-POD-M) is synthesized for efficient bacterial capture (mesoporous spiky structures) and synergistic catalytic sterilization (metal-organic-framework-derived catalytic core). Experimental and theoretical calculations show that the active compound, MoO3 , can serve as a peroxo-complex-intermediate to reduce the free energy for catalyzing H2 O2 , which mainly benefits the generation of •OH radicals. The unique virus-like spikes endow the V-POD-M with fast bacterial capture and killing abilities (nearly 100% at 16 µg mL-1 ). Furthermore, the in vivo experiments show that V-POD-M possesses similar disinfection treatment and wound skin recovery efficiencies to vancomycin. It is suggested that this inexpensive, durable, and highly reactive oxygen species (ROS) catalytic active V-POD-M provides a promising broad-spectrum therapy for nonantibiotic disinfection.


Assuntos
Antibacterianos/síntese química , Materiais Biomiméticos/síntese química , Óxidos/síntese química , Peroxidase/química , Antibacterianos/farmacologia , Materiais Biocompatíveis/química , Materiais Biomiméticos/farmacologia , Catálise , Humanos , Peróxido de Hidrogênio/metabolismo , Estruturas Metalorgânicas/química , Estruturas Metalorgânicas/farmacologia , Simulação de Dinâmica Molecular , Molibdênio/farmacologia , Óxidos/farmacologia , Peroxidase/metabolismo , Esterilização , Vancomicina/farmacologia
6.
Phys Chem Chem Phys ; 23(3): 1943-1955, 2021 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-33463636

RESUMO

The peroxidase-oxidase oscillating reaction was the first (bio)chemical reaction to show chaotic behaviour. The reaction is rich in bifurcation scenarios, from period-doubling to peak-adding mixed mode oscillations. Here, we study a state-of-the-art model of the peroxidase-oxidase reaction. Using the model, we report systematic numerical experiments exploring the impact of changing the enzyme concentration on the dynamics of the reaction. Specifically, we report high-resolution phase diagrams predicting and describing how the reaction unfolds over a quite extended range of enzyme concentrations. Surprisingly, such diagrams reveal that the enzyme concentration has a huge impact on the reaction evolution. The highly intricate dynamical behaviours predicted here are difficult to establish theoretically due to the total absence of an adequate framework to solve nonlinearly coupled differential equations. But such behaviours may be validated experimentally.


Assuntos
Peroxidase/química , Modelos Químicos , NAD/química , Dinâmica não Linear , Oxirredução , Oxigênio/química
7.
J Sci Food Agric ; 101(1): 307-314, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-32623742

RESUMO

BACKGROUND: Polyphenol oxidase (PPO) and peroxidase (POD) are key enzymes associated with shelf life and defense responses. Thus, the activity of PPO and POD enzymes is usually assessed to check the quality of food samples and to understand the physiological responses of plants to different stresses. However, the outcomes of PPO and POD activity assessment studies are highly dependent on assay conditions. Hence, in this study, we initially optimized PPO and POD extraction and high-throughput 96-well plates-based enzymatic activity assessment methods to evaluate the inhibitory potential of tomato volatile compounds. Later, we explored the effects of net-house and open-field growing on the PPO and POD activity in tomato fruits of eight cultivars. RESULTS: We found 150 mM of catechol and pH 7.0 were the optimal conditions for the maximum activity for the PPO assay. Conversely, 24 mM guaiacol with 12 mM H2 O2 and pH 6.0 was the best condition for the POD assay. Thermal inactivation studies confirmed that tomato POD is more resistant to heat than PPO. We found that the production systems had a considerable genotype-specific impact on tomato PPO and POD activity. Moreover, amongst the volatiles that were studied, ß-damascenone and d-limonene showed 50% PPO inhibition at 40 and 80 mM, respectively. CONCLUSION: The results of this study can be used to improve the shelf-life of fresh tomato fruit and its products. The findings also underscore the significance of PPO and POD enzymes as physiological trait markers in the tomato crop and fruit quality improvement programs. © 2020 Society of Chemical Industry.


Assuntos
Catecol Oxidase/química , Lycopersicon esculentum/enzimologia , Peroxidase/química , Ensaios Enzimáticos , Estabilidade Enzimática , Frutas/química , Frutas/enzimologia , Cinética , Odorantes/análise , Compostos Orgânicos Voláteis/química
8.
Methods Mol Biol ; 2198: 169-181, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-32822031

RESUMO

Immunocytochemistry can be instrumental in assessing the spatial distribution and relative levels of epigenetic modifications. Although conventional immunostaining has been utilized for the detection of 5-methylcytosine (5mC) in animal cells and tissues for several decades, the sensitivity of techniques based on the use of fluorophore-conjugated secondary antibodies is not always sufficient for studying DNA modifications that are less abundant in DNA compared with 5mC. Here we describe a protocol for sensitive immunocytochemistry that utilizes peroxidase-conjugated secondary antibodies coupled with catalyzed reporter deposition and allows for detection of low-abundance noncanonical bases (e.g., 5-carboxylcytosine, 5caC, 5-formylcytosine, 5fC, 5-hydroxymethyluracil, 5hmU) in mammalian DNA. This method can be employed for evaluation of the levels and nuclear distribution of DNA modifications and permits their colocalization with protein markers in animal cells.


Assuntos
DNA/imunologia , Imuno-Histoquímica/métodos , 5-Metilcitosina/metabolismo , Animais , Anticorpos/metabolismo , Núcleo Celular/metabolismo , Citosina/análogos & derivados , Citosina/análise , DNA/genética , Metilação de DNA/imunologia , Epigênese Genética/genética , Humanos , Pentoxil (Uracila)/análogos & derivados , Pentoxil (Uracila)/análise , Peroxidase/química
9.
Methods Mol Biol ; 2198: 183-191, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-32822032

RESUMO

The modified cytosine base 5-hydroxymethylcytosine (5hmC) is abundantly present in the central nervous system (CNS), and visualization of global 5hmC levels is possible through use of immunohistochemistry. In this chapter we describe an adaptable method of brain tissue collection and immunohistochemical staining that allows for detection of 5hmC in mouse or rat brain, meaning that the method can be applied to many rodent models of CNS diseases and disorders.


Assuntos
5-Metilcitosina/análogos & derivados , DNA/imunologia , Imuno-Histoquímica/métodos , 5-Metilcitosina/química , 5-Metilcitosina/metabolismo , Animais , Anticorpos/metabolismo , Encéfalo , Núcleo Celular/metabolismo , Citosina , DNA/genética , Metilação de DNA/imunologia , Epigênese Genética/genética , Camundongos , Peroxidase/química , Ratos , Roedores
10.
Carbohydr Polym ; 253: 117239, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33278995

RESUMO

Novel microwave-assisted green in-situ synthesis of positively charged gold nanoparticles (AuNPs) supported by cationic cellulose nanofibrils (C.CNF) within 30 s and devoid of additional reducing agent is reported. Peroxidase activity of these positive AuNPs was studied and that appeared to be superior over its negative charged counterpart. Further the AuNPs@C.CNF is casted into a film which makes it reusable. Using TMB substrate, simple and sensitive colorimetric detection methods for H2O2 and glucose were established. Under optimal conditions, the linear ranges were found to be 0.5-30 µM and 1-60 µM, and the detection limits were 0.30 and 0.67 µM for H2O2 and glucose, respectively. The film was potentially reused for the detection of glucose up to five cycles without a decrease in the activity. Further, this technique was employed to quantify glucose in human serum samples, and the obtained results were comparable with those of the standard GOD-POD method.


Assuntos
Glicemia/análise , Cátions/química , Celulose/química , Ouro/química , Nanopartículas Metálicas/química , Nanofibras/química , Reciclagem , Doadores de Sangue , Colorimetria/métodos , Humanos , Peróxido de Hidrogênio/análise , Cinética , Limite de Detecção , Peroxidase/química , Substâncias Redutoras/química
11.
Chem Commun (Camb) ; 57(2): 148-173, 2021 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-33346275

RESUMO

Myoglobin (Mb) is considered as the optimal system for capturing molecular oxygen (O2) in aqueous solution under natural conditions. Therefore, the preparation of artificial systems that mimic the function of Mb is a long-standing and challenging objective. Various sophisticated iron porphyrins have been designed and synthesized to realize O2 biding at their axial positions. Although all of these compounds reversibly bind O2 in absolute organic solvents, no stable O2 adducts were obtained in aqueous solution. The reason for this is the immediate autoxidation of O2 adducts by water molecules. To achieve O2 binding in aqueous solution, the iron center of the porphyrin must be placed in a hydrophobic environment, wherefrom a water molecule is strictly excluded. Another essential requirement for a Mb model is the preparation of an electron-donative axial ligand that plays the role of proximal histidine (His). As an artificial O2 receptor that satisfies these challenging requirements, a supramolecule termed "hemoCD1" has been constructed. HemoCD1, a 1 : 1 inclusion complex of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphinatoiron(ii) (FeIITPPS) with a per-O-methylated ß-cyclodextrin dimer bearing a pyridine linker (Py3CD), reversibly binds O2 in aqueous solution at neutral pH and ambient temperature. The electronic spectra as well as the functions of hemoCD1 are analogous to those of Mb or its tetramer, hemoglobin (Hb). This is the first example of an artificial Hb/Mb biomimetic model capable of function in aqueous solution. Such a study on hemoCD1 as a Hb/Mb model has expanded research objectives to (1) syntheses of hemoCD1 analogues having distinct characteristics, (2) modeling enzymatic reactions of peroxidase, heme oxygenase, and cytochrome c oxidase in water, (3) development of fully synthetic artificial oxygen carriers (AOCs) utilized in animal blood, and (4) selective binding and removal of toxic small molecules, such as carbon monoxide (CO) and cyanide (CN-) in living organisms.


Assuntos
Heme/química , Modelos Moleculares , Mioglobina/química , Água/química , Animais , Materiais Biomiméticos/química , Materiais Biomiméticos/metabolismo , Monóxido de Carbono/química , Monóxido de Carbono/isolamento & purificação , Monóxido de Carbono/metabolismo , Cianetos/química , Cianetos/isolamento & purificação , Cianetos/metabolismo , Ciclodextrinas/química , Meia-Vida , Concentração de Íons de Hidrogênio , Cinética , Mioglobina/metabolismo , Oxirredução , Oxigênio/química , Oxigênio/metabolismo , Peroxidase/química , Peroxidase/metabolismo , Ratos
12.
J Dairy Sci ; 104(2): 1548-1559, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309341

RESUMO

Textiles represent promising support materials for enzymes. The goal of the present work was to investigate the immobilization of commercial peroxidase on a polyester needle felt and the repeated use in the gentle degradation of norbixin in whey from dairy cheese as a practical application. High enzyme loads were obtained by a 2-step immobilization procedure. First, the number of functional groups on the textile surface was increased by a modification with amino-functional polyvinylamine. Second, the enzyme was immobilized by using 2 types of crosslinking agents. Due to the iron content of peroxidase, inductively coupled plasma-optical emission spectrometry was used for the quantitative determination of the enzyme load on the textile. The enzyme activity was evaluated using common 2,2'-azino-di-(3-ethylbenzthiazoline-6-sulfonic acid) assay for peroxidases. By the variation of enzyme input and crosslinker concentration, a maximal enzyme load of 80 mg/g of textile was achieved, and a maximum specific activity of 57 U/g of textile. For the visualization of the enzyme on the fiber surface, fluorescence microscopy as well as scanning probe microscopy were used. The immobilized peroxidase showed significant activity, even after 50 reuse cycles. In addition, the potential of the new support and enzyme combination in commercial whey bleaching was demonstrated successfully on a 10-L scale.


Assuntos
Clareadores/química , Carotenoides/metabolismo , Queijo , Peroxidase/química , Soro do Leite/química , Clareadores/metabolismo , Cor , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Peroxidase/metabolismo , Poliésteres/química , Têxteis
13.
Food Chem ; 339: 128088, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32979714

RESUMO

Flavonol glycosides are associated with astringency and bitterness of teas. To clarify the dominant enzymatic reaction of flavonol glycosides in tea leaves, the catalytic effects of polyphenol oxidase (PPO), peroxidase (POD) and ß-glucosidase were studied, with the maintaining rates of total flavonol glycosides (TFG) being 73.0%, 99.8% and 94.3%. PPO was selected for further investigations, including the effects of pH value (3.5 ~ 6.5), temperature (25 °C ~ 55 °C) and dosage (39 ~ 72 U/mL PPO and 36 U/mL PPO, 3 ~ 36 U/mL POD). The oxidation of flavonol glycosides were intensified at pH 6.5, with 51.8% and 15.4% of TFG maintained after PPO and PPO + POD treatments, suggesting an enhancement from POD. The sensitivity ranking to PPO was: myricetin glycosides > quercetin glycosides > kaempferol glycosides. The inhibitor treatment testified the leading role of PPO in catalyzing flavonol glycosides in tea leaves. Sugar moiety enhanced the docking affinity of flavonol glycosides for PPO. PPO shows the potential of modifying flavonol glycoside composition.


Assuntos
Camellia sinensis/metabolismo , Catecol Oxidase/metabolismo , Flavonóis/metabolismo , Folhas de Planta/metabolismo , Camellia sinensis/química , Catecol Oxidase/química , Flavonoides/química , Flavonoides/metabolismo , Flavonóis/química , Glicosídeos/química , Concentração de Íons de Hidrogênio , Quempferóis/química , Quempferóis/metabolismo , Oxirredução , Peroxidase/química , Peroxidase/metabolismo , Extratos Vegetais/química , Extratos Vegetais/metabolismo , Folhas de Planta/química , Chá/química , Temperatura , beta-Glucosidase/química , beta-Glucosidase/metabolismo
14.
Anal Chim Acta ; 1106: 115-125, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32145839

RESUMO

Two-dimentional layered WS2 nanosheets with rich active edge exhibit intrinsic peroxidase-mimic activity, which make them an ideal material for sensor design. However, there is still lack of research on the catalysis and regulation mechanisms of the layered WS2 nanosheets as well as their application in the detection of hazardous substances. Herein, the regulatory effect of Pb(II) on the peroxidase-mimic activity of the layered WS2 nanosheets was firstly investigated, which enable us to construct a novel and facile colorimetric sensor for ultrasensitive and selective detection of Pb(II). To improve the performance of colorimetric sensor, some important parameters like buffer conditions, substrates and temperature have been investigated. Under the optimal conditions, the catalytic kinetics of layered WS2 nanosheets were extensively investigated. The peroxidase-mimic catalytic reaction was proved to be the "ping pong" mechanism, and the regulatory effect of Pb(II) on layered WS2 nanosheets was agreed with noncompetitive inhibition. The absorbance variation of colorimetric sensor is proportionally related to the concentration of heavy metals, which enable us to easily distinguish whether Pb(II) exceeds the permissible level in less than 20 min even by the naked eyes. The limit of detection (LOD) and the limit of quantification (LOQ) of the proposed colorimetric sensor for Pb(II) were determined as low as 4 µg L-1 and 13.3 µg L-1, and displays excellent selectivity against other competitive metal ions. Moreover, the further studies also validate the applicability of colorimetric sensor in several actual samples, indicating that our strategy may has prospective applications for Pb(II) detection in environment and biological samples.


Assuntos
Colorimetria , Poluentes Ambientais/análise , Chumbo/análise , Nanoestruturas/química , Peroxidase/metabolismo , Sulfetos/metabolismo , Compostos de Tungstênio/metabolismo , Animais , Biocatálise , Monitoramento Ambiental , Poluentes Ambientais/metabolismo , Peixes , Radical Hidroxila/análise , Chumbo/metabolismo , Tamanho da Partícula , Peroxidase/química , Sulfetos/química , Propriedades de Superfície , Compostos de Tungstênio/química
15.
Enzyme Microb Technol ; 135: 109490, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32146936

RESUMO

Bioproducts production using monomeric sugars derived from lignocellulosic biomass presents several challenges, such as to require a physicochemical pretreatment to improve its conversion yields. Hydrothermal lignocellulose pretreatment has several advantages and results in solid and liquid streams. The former is called hemicellulosic hydrolysate (HH), which contains inhibitory phenolic compounds and sugar degradation products that hinder microbial fermentation products from pentose sugars. Here, we developed and applied a novel enzyme process to detoxify HH. Initially, the design of experiments with different redox activities enzymes was carried out. The enzyme mixture containing the peroxidase (from Armoracia rusticana) together with superoxide dismutase (from Coptotermes gestroi) are the most effective to detoxify HH derived from sugarcane bagasse. Butanol fermentation by the bacteria Clostridium saccharoperbutylacetonicum and ethanol production by the yeast Scheffersomyces stipitis increased by 24.0× and 2.4×, respectively, relative to the untreated hemicellulosic hydrolysates. Detoxified HH was analyzed by chromatographic and spectrometric methods elucidating the mechanisms of phenolic compound modifications by enzymatic treatment. The enzyme mixture degraded and reduced the hydroxyphenyl- and feruloyl-derived units and polymerized the lignin fragments. This strategy uses biocatalysts under environmentally friendly conditions and could be applied in the fuel, food, and chemical industries.


Assuntos
Clostridium/metabolismo , Peroxidase/química , Polissacarídeos/química , Saccharum/química , Superóxido Dismutase/química , Leveduras/metabolismo , Biocatálise , Butanóis/metabolismo , Celulose/química , Celulose/metabolismo , Fermentação , Microbiologia Industrial , Peroxidase/metabolismo , Polissacarídeos/metabolismo , Saccharum/microbiologia , Superóxido Dismutase/metabolismo
16.
Mikrochim Acta ; 187(4): 226, 2020 03 13.
Artigo em Inglês | MEDLINE | ID: mdl-32170394

RESUMO

Heparin was employed as the stabilizing agent in the synthesis of peroxidase-mimicking Pd nanoparticles. The heparin-capped Pd nanozyme can act as both the signal amplifier and the selective binder of protamine. The most efficient nanozyme with the mean size of 3.5 nm consists of 70.8% metallic Pd0 and 29.2% Pd2+ species. Enzyme kinetic studies show that the Km values are 0.036 mM for 3,3',5,5'-tetramethylbenzidine and 78 mM for H2O2. Protamine shows strong affinity to the heparin-capped Pd nanozyme, and induces an apparent aggregation of the nanoparticles. This results in a significant inhibition of the peroxidase-mimicking activities. Hence, the oxidation of TMB by H2O2 to a blue product with a maximum absorption at 652 nm is suppressed. Based on this finding, a photometric assay is developed for the determination of protamine. The linear response is in the concentration range 0.02 ~ 0.8 µg mL-1, and the limit of detection is 0.014 µg mL-1. This assay presents high selectivity toward other biological substances. Graphical abstract Highly active and selective Pd nanozyme was synthesized through adopting heparin as the capping agent for quantitative determination of protamine.


Assuntos
Heparina/química , Nanopartículas/química , Paládio/química , Peroxidase/química , Fotometria , Protaminas/análise , Heparina/metabolismo , Nanopartículas/metabolismo , Paládio/metabolismo , Peroxidase/metabolismo , Protaminas/metabolismo
17.
ACS Appl Mater Interfaces ; 12(10): 11320-11328, 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32067461

RESUMO

Nanomaterials with intrinsic peroxidase-like activities are able to catalyze the oxidation of the substrate with the peroxide, which have been widely considered as artificial enzymatic agents in cancer therapy. However, current peroxidase catalytic oxidation treatments generating reactive oxygen species rely highly on hydrogen peroxide and pH, which limit greatly their therapeutic efficiency in the tumor microenvironment. Here, we report a strategy to construct the complex virus-like Fe3O4@Bi2S3 nanocatalysts (F-BS NCs) by connecting typical peroxidase Fe3O4 (MNPs) with a narrow band gap semiconductor Bi2S3 (BS) to enhance the enzymatic activity resorting to the limited intratumoral peroxide and efficient external photothermal stimuli. In this formulation, the integrated F-BS NCs induce cancer-cell death through mild photothermal treatment and sequential photothermal-stimulative catalysis of H2O2 into highly toxic •OH under 808 nm laser, which successfully realize a remarkable synergistic anticancer achievement.


Assuntos
Antineoplásicos , Hipertermia Induzida , Nanopartículas de Magnetita/química , Nanomedicina/métodos , Peroxidase , Animais , Antineoplásicos/química , Antineoplásicos/metabolismo , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Linhagem Celular , Sinergismo Farmacológico , Células HeLa , Humanos , Camundongos , Oxirredução , Peroxidase/química , Peroxidase/metabolismo , Peroxidase/farmacologia
18.
Biosens Bioelectron ; 153: 112055, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32056659

RESUMO

Immobilized dye-decolorizing peroxidase from Pseudomonas putida MET94 (PpDyP) and three variants generated by directed evolution (DE) are studied aiming at the design of a biosensor for H2O2 detection. Structural properties of the enzymes in solution and immobilized state are addressed by resonance Raman (RR) and surface enhanced RR (SERR) spectroscopy, and the electrocatalytic properties are analyzed by electrochemistry. The wild-type (wt) and 29E4 variant (with E188K and H125Y mutations) represent excellent candidates for development of H2O2 biosensors, since they exhibit a good dynamic response range (1-200 µM H2O2), short response times (2 s) and a superior sensitivity (1.3-1.4 A⋅M-1⋅cm-2) for H2O2, as well as selectivity and long term stability. In contrast to the solution state, 6E10 (with E188K, A142V and H125Y mutations) and 25F6 (with E188K, A142V, H125Y and G129D mutations) variants display much lower activity and are inhibited by high concentrations of H2O2 upon adsorption on an electrode. In terms of sensitivity, the bioelectrodes employing wt PpDyP and 29E4 variant outperform HRP based counterparts reported in the literature by 1-4 orders of magnitude. We propose the development of wt or 29E4 PpDyP based biosensor as a valuable alternative to devices that rely on peroxidases.


Assuntos
Técnicas Biossensoriais , Enzimas Imobilizadas/química , Peróxido de Hidrogênio/isolamento & purificação , Peroxidase/química , Corantes/química , Peróxido de Hidrogênio/química , Pseudomonas putida/enzimologia
19.
ACS Appl Mater Interfaces ; 12(8): 8989-8999, 2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-32023028

RESUMO

The efficient fabrication of multifunctional nanoplatforms for bacterial detection and elimination is of great importance in nanobiotechnology. A new porphyrin-based porous organic polymer, FePPOPBFPB, was synthesized via the reaction between pyrrole and 4-{2,2-bis[(4-formylphenoxy)methyl]-3-(4-formylphenoxy) propoxy} benzaldehyde (BFPB). The C-centric tetrahedral structure of BFPB promoted the formation of FePPOPBFPB with a 3D interconnected porous structure, high specific surface area, and plentiful surface catalytic active sites. The adjustable structural alkyl chain also enhanced the absorption capability of FePPOPBFPB in the long-wavelength visible and near-infrared regions (NIR). FePPOPBFPB exhibited excellent peroxidase-like activity toward a representative peroxidase substrate, 3,3',5,5'-tetramethylbenzidine (TMB) with H2O2. Utilizing these features, a rapid and visual detection of Staphylococcus aureus (S. aureus) based on FePPOPBFPB was established and exhibited high sensitivity and stability. Combining the catalysis with near-infrared-light (NIR) absorption, FePPOPBFPB can effectively catalyze the decomposition of biologically relevant concentrations of H2O2 to produce vast amounts of •OH radicals via the photo-Fenton reaction, which avoids the utilization of high toxic concentrations of H2O2. On the basis of these satisfactory features, FePPOPBFPB had a conspicuous bactericidal performance against S. aureus under NIR irradiation. To our knowledge, this is the first example of a porphyrin-based porous organic polymer antibacterial agent. The main reactive oxygen species (ROS) produced in this system and the possible antibacterial mechanism of FePPOPBFPB was also proposed through a series of experiments.


Assuntos
Antibacterianos , Raios Infravermelhos , Peroxidase/química , Polímeros/química , Porfirinas/química , Staphylococcus aureus/crescimento & desenvolvimento , Antibacterianos/química , Antibacterianos/farmacologia , Porosidade
20.
ACS Appl Mater Interfaces ; 12(8): 9090-9097, 2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-32023032

RESUMO

It is important to detect pathogens rapidly, sensitively, and selectively for clinical medicine, homeland security, food safety, and environmental control. We report here a specific and sensitive colorimetric assay that incorporated a bovine serum albumin-templated Co3O4 magnetic nanozyme (Co3O4 MNE) with a novel specific fusion phage protein and magnetophoretic chromatography to detect Staphylococcus aureus. The Co3O4 MNE was conjugated to S. aureus-specific fusion-pVIII (Co3O4 MNE@fusion-pVIII), screened from the S. aureus-specific phage AQTFLGEQD (the phage monoclone is denoted by the peptide sequence). The as-prepared triple-functional Co3O4 MNE@fusion-pVIII particles were capable of capturing S. aureus in sterile milk, which were then isolated from milk magnetically. Assisted by polyethylene glycol, the Co3O4 MNE@fusion-pVIII@S. aureus complex was separated from the free Co3O4 MNE@fusion-pVIII by magnetophoretic chromatography in an external magnetic field. After transferring the isolated Co3O4 MNE@fusion-pVIII@S. aureus complexes into a 96-well plate, diammonium salt of 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) and H2O2 were added to develop color because of the peroxidase mimetics activity of the Co3O4 MNE. A S. aureus concentration within 10-10,000 cfu/mL in milk can be detected (detection limit: 8 cfu/mL). The as-developed method is simple, cost-efficient, and sensitive, which is useful for rapidly diagnosing pathogenic bacteria and helpful to prevent disease outbreaks induced by pathogens in developing countries.


Assuntos
Cobalto/química , Microbiologia de Alimentos , Leite/microbiologia , Nanopartículas/química , Óxidos/química , Peroxidase/química , Fagos de Staphylococcus/química , Staphylococcus aureus/metabolismo , Proteínas Virais de Fusão/química , Animais , Colorimetria , Campos Magnéticos , Staphylococcus aureus/virologia
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