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1.
Food Chem ; 366: 130560, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34284183

RESUMO

The colorimetric method can determine the initial results even by the naked eyes, but its main challenge for antibiotics detection in food at present is the relatively low sensitivity. Herein, an ultrasensitive colorimetric biosensor based on G-quadruplex DNAzyme was firstly proposed for the rapid detection of trace tetracycline antibiotics like tetracycline, oxytetracycline, chlortetracycline and doxycycline. DNAzyme composed of hemin and G-quadruplex has peroxidase-like activity, and tetracyclines can combine with hemin to form a stable complex and reduce catalytic activity, making the color of solution changes from yellow to green. The limits of detection (LOD) of the proposed colorimetric biosensor for tetracyclines is determined as low as 3.1 nM, which is lower than most of the other colorimetric methods for antibiotics detection. Moreover, the average recovery range of tetracyclines in actual samples is from 89% to 99%, indicating that such strategy may has bright application prospects for tetracyclines detection in foods.


Assuntos
Técnicas Biossensoriais , DNA Catalítico , Tetraciclinas/análise , Antibacterianos , Colorimetria , Quadruplex G , Hemina , Peroxidase , Peroxidases
2.
Enzyme Microb Technol ; 151: 109917, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34649688

RESUMO

Lignin is a major byproduct of pulp and paper industries, which is resistant to depolymerization due to its heterogeneous structure. The enzymes peroxidases can be utilized as potent bio-catalysts to degrade lignin. In the current study, an Efeb gene of 1251bp encoding DyP-type peroxidase from Bacillus sp. strain BL5 (DyPBL5) was amplified, cloned into a pET-28a (+) vector and expressed in Escherichia coli BL21 (DE3) cells. A 46 kDa protein of DyPBL5 was purified through ion-exchange chromatography. Purified DyPBL5 was active at wide temperature (25-50 °C) and pH (3.0-8.0) range with optimum activity at 35 °C and pH 5.0. Effects of different chemicals on DyPBL5 were determined. The enzyme activity was strongly inhibited by SDS, DDT and ß-mercaptoethanol, whereas stimulated in the presence of organic solvents such as methanol and ethanol. The kinetic parameters were determined and Km, Vmax and Kcat values were 1.06 mM, 519.75 µmol/min/mg and 395 S̶ 1, respectively. Docking of DyPBL5 with ABTS revealed that, Asn 244, Arg 339, Asp 383 and Thr 389 are putative amino acids, taking part in the oxidation of ABTS. The recombinant DyPBL5 resulted in the reduction of lignin contents up to 26.04 %. The SEM and FT-IR analysis of test samples gave some indications about degradation of lignin by DyPBL5. Various low molecular weight lignin degradation products were detected by analyzing the samples through gas chromatography mass spectrometry. High catalytic efficiency and lignin degradation rate make DyPBL5 an ideal bio-catalyst for remediation of lignin-contaminated sites.


Assuntos
Bacillus , Lignina , Bacillus/genética , Clonagem Molecular , Peroxidases/genética , Espectroscopia de Infravermelho com Transformada de Fourier
3.
An Acad Bras Cienc ; 93(suppl 3): e20210296, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34586183

RESUMO

Fungi are excellent producers of extracellular enzymes. Therefore, the present study aimed to investigate the screening of marine fungi, which are laccase and manganese peroxidase potential producers, in solid fermentation for future applications in bioremediation processes of contaminated sites. For this purpose, two-level factorial planning was adopted, using time (6 and 15 days) and the absence or presence of oil (0 and 1%) as factors. The semi-quantitative evaluation was carried out by calculating radial growth, enzyme activity and enzyme index by measuring phenol red or syringaldazine oxidation halo. The results showed that all the studied strains showed a positive result for manganese peroxidase production, with an enzymatic activity in solid medium less than 0.61, indicating a strongly positive activity. Through the enzyme index, the study also showed prominence for Penicillium sp. strains, with values > 2. The enzyme index increase in oil presence and the inexpressive use of the genera studied for ligninolytic enzymes production from crude oil demonstrated these data importance for fermentative processes optimization. Considering the ability of these strains to develop into recalcitrant compounds and the potential for manganese peroxidase production, they are indicated for exploitation in various bioremediation technologies, as well as other biotechnological applications.


Assuntos
Lacase , Peroxidases , Biodegradação Ambiental , Meios de Cultura , Fermentação , Fungos/metabolismo , Peroxidases/metabolismo
4.
Mater Sci Eng C Mater Biol Appl ; 129: 112404, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34579916

RESUMO

Herein a nano-scale bimetallic Fe/Eu-MOF with a regular octahedral structure was synthesized for the first time. The synthesized Fe/Eu-MOF has both peroxidase-like activity and fluorescence properties. Fe/Eu-MOF can catalyze H2O2 to oxidize the chromogenic substrate TMB to produce blue oxTMB, which has ultraviolet absorption at 652 nm. Unexpectedly, the generated oxTMB can effectively quench the fluorescence of the catalyst Fe/Eu-MOF at 450 nm. The quenching mechanism is mainly the internal filtration effect (IFE), accompanied by static quenching (SQE), Förster resonance energy transfer (FRET) and photoelectron transfer (PET). Fe/Eu-MOF has a high affinity for sodium pyrophosphate (PPi). PPi can be adsorbed to the surface of Fe/Eu-MOF, destroying the structure of Fe/Eu-MOF and inhibiting its catalytic activity, resulting in a decrease in UV absorbance and the decline of fluorescence quenching. In contrast, phosphoric acid (Pi) has almost no effect on the reaction system. Alkaline phosphatase (ALP) can catalyze the hydrolysis of PPi to Pi, thereby reducing the inhibitory effect of PPi. Based on this, we successfully constructed a dual-mode ALP sensor with high selectivity. The linear ranges based on the 652 nm absorption or the fluorescence detection are from 1 to 200 U/L, and the detection limits are 0.6 for the absorption method and 0.9 U/L for the fluorescence method, respectively.


Assuntos
Fosfatase Alcalina , Peroxidase , Corantes Fluorescentes , Peróxido de Hidrogênio , Peroxidases
5.
Anal Chem ; 93(36): 12353-12359, 2021 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-34469123

RESUMO

Although single-atom catalysts with high enzyme-like activities have been found, the rational design of highly active peroxidase (POD)-like nanozymes is still a formidable challenge. Herein, highly active POD-like nanozymes were synthesized through loading Pt clusters on the Fe single-atom (FeSA-PtC) nanozymes. The POD-like activity of FeSA-PtC nanozymes is enhanced 4.5-fold and 7-fold, in comparison to that of FeSA and PtC nanozymes, respectively, which is attributed to the unexpected synergistic effect between Fe single atoms and Pt clusters. Based on the outstanding POD-like activity of FeSA-PtC nanozymes, a cascade signal amplification strategy was constructed by combining glucose oxidase for the colorimetric biosensing of prostate-specific antigens, exhibiting satisfactory sensitivity, high selectivity, a low detection limit of 1.8 pg/mL, and practical feasibility in serum sample detection. This work may serve as a tough foundation to guide the design of superior POD-like nanozymes and expand the application in biosensing.


Assuntos
Técnicas Biossensoriais , Colorimetria , Peróxido de Hidrogênio , Imunoensaio , Peroxidases
6.
Anal Chim Acta ; 1180: 338740, 2021 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-34538313

RESUMO

Total Antioxidant Capacity (TAC) Assay plays an important role in evaluating the quality of antioxidant food and monitoring the oxidative stress level of human body. It is mainly achieved by measuring the contents of antioxidants such as AA, L-Cys and GSH, while TAC can be detected by using peroxidase-like activity of artificial nanoenzyme materials. In this work, the N-Doped, defect-rich N-MoS2NFs nano-materials were used to build the nano enzyme, which has strong stability and high peroxidase-like activity. H2O2 was detected because it can be catalyzed to generate the intermediate ·OH and make TMB appears blue. However, when H2O2, AA, L-Cys and GSH coexist in solution, due to the oxidation resistance of AA, L-Cys and GSH, they can competitively react with ·OH in solution or reduce TMB in oxidation state (oxTMB), which reduces the characteristic absorption of oxTMB, indirectly achieves the purpose of detecting AA, L-Cys and GSH, and finally realizes the determination of TAC, even in actual serum and saliva samples. At the same time, the N-MoS2 NFs/NH2-MIL-53(Al)+OPD system is further constructed. Based on the fluorescence resonance energy transfer (FRET) between NH2-MIL-53(Al) and oxidized OPD (oxOPD), the purpose of detecting TAC by fluorescence method was realized.


Assuntos
Antioxidantes , Peroxidase , Colorimetria , Humanos , Peróxido de Hidrogênio , Molibdênio , Peroxidases
7.
Sensors (Basel) ; 21(16)2021 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-34450980

RESUMO

Copper (II) ions have been shown to greatly improve the chemical stability and peroxidase-like activity of gold nanoclusters (AuNCs). Since the affinity between Cu2+ and pyrophosphate (PPi) is higher than that between Cu2+ and AuNCs, the catalytic activity of AuNCs-Cu2+ decreases with the introduction of PPi. Based on this principle, a new colorimetric detection method of PPi with high sensitivity and selectivity was developed by using AuNCs-Cu2+ as a probe. Under optimized conditions, the detection limit of PPi was 0.49 nM with a linear range of 0.51 to 30,000 nM. The sensitivity of the method was three orders of magnitude higher than that of a fluorescence method using AuNCs-Cu2+ as the probe. Finally, the AuNCs-Cu2+ system was successfully applied to directly determine the concentration of PPi in human urine samples.


Assuntos
Ouro , Nanopartículas Metálicas , Colorimetria , Cobre , Difosfatos , Corantes Fluorescentes , Humanos , Limite de Detecção , Peroxidase , Peroxidases , Espectrometria de Fluorescência
8.
Bioresour Technol ; 340: 125655, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34388661

RESUMO

Lignin is a wasted renewable source of biomass-derived value-added chemicals. However, due to its material resistance to degradation, it remains highly underutilized. In order to develop new, catalysed and more environment friendly reaction processes for lignin valorization, science has turned a selective concentrated attention to microbial enzymes. This present work looks at the enzymes involved with the main reference focus on the different elementary mechanisms of action/conversion rate kinetics. Pathways, like with laccases/peroxidases, employ radicals, which more readily result in polymerization than de-polymerization. The ß-etherase system interaction of proteins targets ß-O-4 ether covalent bond, which targets lower molecular weight product species. Enzymatic activity is influenced by a wide variety of different factors which need to be considered in order to obtain the best functionality and synthesis yields.


Assuntos
Lacase , Lignina , Biomassa , Cinética , Lacase/metabolismo , Peroxidases/metabolismo
9.
Talanta ; 234: 122645, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34364454

RESUMO

In view of the broad application prospect of peroxidase-like nanozymes in biomedical analysis, it is of great significance to eliminate the interference of their oxidase-like activity and enable them to work under neutral conditions. Herein, flower-like NiV2O6 was synthesized and their enzyme-mimicking activity was investigated. Through the regulation of pH, NiV2O6 nanozyme showed only peroxidase-like activity but not oxidase-like activity under neutral conditions, which could catalyze the oxidation of colorless 3,3',5,5'-tetramethylbenzidine into its blue product in the presence of H2O2. Furthermore, based on the competitive effect of glutathione (GSH) on the catalytic activity of nanozymes, a semi-quantitative/quantitative colorimetric assay was established for GSH detection by using peroxidase-like NiV2O6. The assay exhibited a good linear relationship in GSH concentration ranging from 3-100 µmol L-1, with a detection limit of 0.89 µmol L-1. Moreover, in the presence of formaldehyde as masking agent, this method showed satisfactory specificity for GSH under the interference of a variety of interfering substances and even biothiols. Concerning the practical application, the system was applied to monitor GSH level in fetal bovine serum, human serum and SiHa cells. Satisfyingly, the obtained results were consistent well with those of Ultra performance liquid chromatography (UPLC) and assay kit, indicating the constructed assay has great potential in clinical application.


Assuntos
Glutationa , Peróxido de Hidrogênio , Colorimetria , Humanos , Concentração de Íons de Hidrogênio , Peroxidase , Peroxidases
10.
Biochim Biophys Acta Gene Regul Mech ; 1864(10): 194734, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34339889

RESUMO

Glutathione peroxidase 7 (GPx7) acts as an intracellular stress sensor/transmitter and plays an important role in adipocyte differentiation and the prevention of obesity related pathologies. For this reason, finding the regulatory mechanisms that control GPx7 expression is of great importance. As microRNAs (miRNAs) could participate in the regulation of GPx7 expression, we studied the inhibition of GPx7 expression by four selected miRNAs with relation to obesity and adipogenesis. The effect of the transfection of selected miRNAs mimics on GPx7 expression was tested in three cell models (HEK293, SW480, AT-MSC). The interaction of selected miRNAs with the 3'UTR of GPx7 was followed up on using a luciferase gene reporter assay. In addition, the levels of GPx7 and selected miRNAs in adipose tissue mesenchymal stem cells (AT-MSC) and mature adipocytes from four human donors were compared, with the changes in these levels during adipogenesis analyzed. Our results show for the first time that miR-137 and miR-29b bind to the 3'UTR region of GPx7 and inhibit the expression of this enzyme at the mRNA and protein level in all the human cells tested. However, no negative correlation between miR-137 nor miR-29b level and GPx7 was observed during adipogenesis. Despite the confirmed inhibition of GPx7 expression by miR-137 and miR-29b, the action of these two molecules in adipogenesis and mature adipocytes must be accompanied by other regulators.


Assuntos
Adipogenia/genética , Regulação Enzimológica da Expressão Gênica , MicroRNAs/metabolismo , Peroxidases/genética , Regiões 3' não Traduzidas , Adipócitos/metabolismo , Linhagem Celular Tumoral , Células Cultivadas , Feminino , Humanos , Pessoa de Meia-Idade , RNA Mensageiro/metabolismo , Células-Tronco/metabolismo
11.
Biomater Sci ; 9(18): 6142-6152, 2021 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-34346413

RESUMO

Heme binds to a parallel-stranded G-quadruplex DNA to form a peroxidase-mimicking heme-DNAzyme. An interpolyelectrolyte complex between the heme-DNAzyme and a cationic copolymer possessing protonated amino groups was characterized and the peroxidase activity of the complex was evaluated to elucidate the effect of the polymer on the catalytic activity of the heme-DNAzyme. We found that the catalytic activity of the heme-DNAzyme is enhanced through the formation of the interpolyelectrolyte complex due to the general acid catalysis of protonated amino groups of the polymer, enhancing the formation of the iron(IV)oxo porphyrin π-cation radical intermediate known as Compound I. This finding indicates that the polymer with protonated amino groups can act as a cocatalyst for the heme-DNAzyme in the oxidation catalysis. We also found that the enhancement of the activity of the heme-DNAzyme by the polymer depends on the local heme environment such as the negative charge density in the proximity of the heme and substrate accessibility to the heme. These findings provide novel insights as to molecular design of the heme-DNAzyme for enhancing its catalytic activity.


Assuntos
DNA Catalítico , Cátions , Heme , Peroxidase , Peroxidases , Polímeros
12.
Int J Mol Sci ; 22(16)2021 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-34445389

RESUMO

DyP-type peroxidases are a family of heme peroxidases named for their ability to degrade persistent anthraquinone dyes. DyP-type peroxidases are subclassified into three classes: classes P, I and V. Based on its genome sequence, Streptomyces avermitilis, eubacteria, has two genes presumed to encode class V DyP-type peroxidases and two class I genes. We have previously shown that ectopically expressed SaDyP2, a member of class V, indeed has the characteristics of a DyP-type peroxidase. In this study, we analyzed SaDyP1, a member of the same class V as SaDyP2. SaDyP1 showed high amino acid sequence identity to SaDyP2, retaining a conserved GXXDG motif and catalytic aspartate. SaDyP1 degraded anthraquinone dyes, which are specific substrates of DyP-type peroxidases but not azo dyes. In addition to such substrate specificity, SaDyP1 showed other features of DyP-type peroxidases, such as low optimal pH. Furthermore, immunoblotting using an anti-SaDyP2 polyclonal antibody revealed that SaDyP1 and/or SaDyP2 is expressed in mycelia of wild-type S. avermitilis.


Assuntos
Peroxidases/genética , Peroxidases/metabolismo , Streptomyces/enzimologia , Sequenciamento Completo do Genoma/métodos , Motivos de Aminoácidos , Sequência de Aminoácidos , Antraquinonas/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Estabilidade Enzimática , Regulação Bacteriana da Expressão Gênica , Regulação Enzimológica da Expressão Gênica , Genoma Bacteriano , Concentração de Íons de Hidrogênio , Modelos Moleculares , Peroxidases/química , Conformação Proteica , Streptomyces/genética , Termodinâmica
13.
Plant Physiol Biochem ; 167: 577-585, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34461554

RESUMO

Sweetpotato (Ipomoea batatas [L.] Lam) is a prospective food crop that ensures food and nutrition security under the dynamic changes in global climate. Peroxidase (POD) is a multifunctional enzyme involved in diverse plant physiological processes, including stress tolerance and cell wall lignification. Although various POD genes were cloned and functionally characterized in sweetpotato, the role of POD in lignification and low-temperature storage ability of sweetpotato tuberous roots is yet to be investigated. In this study, we isolated the cold-induced lignin forming peroxidase (IbLfp) gene of sweetpotato, and analyzed its physiological functions. IbLfp showed more predominant expression in fibrous roots than in other tissues. Moreover, IbLfp expression was up-regulated in leaves and roots under cold stress, and was altered by other abiotic stresses. Tuberous roots of transgenic sweetpotato lines overexpressing IbLfp (LP lines) showed improved tolerance to low temperature, with lower malondialdehyde and hydrogen peroxide contents than non-transgenic sweetpotato plants under cold stress. The enhanced cold tolerance of LP lines could be attributed to the increased basal activity of POD, which is involved in reactive oxygen species (ROS) scavenging. Moreover, greater accumulation of lignin could also contribute to the enhanced cold tolerance of LP lines, as lignin acts as a protective barrier against invading pathogens, which is a secondary symptom of chilling injury in sweetpotato. Overall, the results of this study enhance our understanding of the function of POD in low-temperature storage of sweetpotato tuberous roots.


Assuntos
Ipomoea batatas , Resposta ao Choque Frio , Regulação da Expressão Gênica de Plantas , Ipomoea batatas/genética , Peroxidases , Plantas Geneticamente Modificadas , Estudos Prospectivos , Temperatura
14.
Anal Chem ; 93(32): 11123-11132, 2021 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-34342969

RESUMO

Enzymes are still indispensable for bio-assaying methods in biomolecule detection by far. The unsatisfied long-term instability, high cost, and susceptibility to the physical environment of natural enzymes are obvious weak points. Here, we developed peroxidase-like heterostructured nanozyme, vertically arraying molybdenum disulfide nanosheets on a substrate layer of nitrogen-doped reduced graphene oxide (MoS2/N-rGO), with a well-pleasing stability that is characterized by the retained enzymatic activity and maintained structure after 2 years of casual storage at ambient temperatures or 80 cycles of catalytic reaction. The catalytic kinetics of the as-prepared heterostructured nanozyme was superior to some reported nanozymes and even horse radish peroxidase, which was demonstrated due to the defect-rich MoS2 with Mo and S vacancies and nitrogen-doped rGO experimentally and theoretically. The vertically heterostructured nanozyme exhibited adequate analytical performance in sensitive and quantitative detection of glucose and glutathione (GSH), with a large dynamic sensing range and extremely low limit of detection (0.02 and 0.12 µM (3σ/slope) for glucose and GSH, respectively). We hope this inspired artificial nanozyme will contribute to the future development in sensitive detection of other biomolecules in physiological conditions.


Assuntos
Grafite , Molibdênio , Catálise , Peroxidases
15.
ACS Appl Mater Interfaces ; 13(33): 39719-39729, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34392680

RESUMO

In this work, cucurbiturils (CBs), a class of macrocyclic supramolecules, were observed to have an interesting peroxidase-like activity, which is metal-free, substrate-specific, thermophilic, acidophilic, and insensitive to ionic strength. By coating CBs on enzyme-encapsulated zeolitic imidazolate framework-8 (ZIF-8), a composite nanozyme was constructed, which retains the catalytic ability of CBs and enzymes and makes them cascade. On addition of the substrate, i.e., the detection target, a highly efficient cascade catalysis can be launched in all the spatial directions to generate sensitive and visible signals. Convenient detection of glucose and cholesterol as models is thereby achieved. More importantly, we have also successfully constructed a composite nanozyme-based sensor array (6 × 8 wells) and thereby achieved simultaneous colorimetric analysis of multiple samples. The concept and successful practice of the construction of the unique core-shell supramolecule/biomolecule@nanomaterial architecture provide the possibility to fabricate next-generation multifunctional materials and create new applications by integrating their unique functions.


Assuntos
Hidrocarbonetos Aromáticos com Pontes/química , Imidazóis/química , Nanocompostos/química , Peroxidases/química , Zeolitas/química , Técnicas Biossensoriais , Hidrocarbonetos Aromáticos com Pontes/metabolismo , Catálise , Colorimetria , Corantes Fluorescentes/química , Glucose Oxidase/química , Glucose Oxidase/metabolismo , Peróxido de Hidrogênio/química , Imidazóis/metabolismo , Simulação de Acoplamento Molecular , Oxirredução , Peroxidases/metabolismo , Impressão Tridimensional
16.
Molecules ; 26(15)2021 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-34361556

RESUMO

Wastewater emissions from textile factories cause serious environmental problems. Manganese peroxidase (MnP) is an oxidoreductase with ligninolytic activity and is a promising biocatalyst for the biodegradation of hazardous environmental contaminants, and especially for dye wastewater decolorization. This article first summarizes the origin, crystal structure, and catalytic cycle of MnP, and then reviews the recent literature on its application to dye wastewater decolorization. In addition, the application of new technologies such as enzyme immobilization and genetic engineering that could improve the stability, durability, adaptability, and operating costs of the enzyme are highlighted. Finally, we discuss and propose future strategies to improve the performance of MnP-assisted dye decolorization in industrial applications.


Assuntos
Corantes/química , Enzimas Imobilizadas/química , Peroxidases/química , Têxteis , Águas Residuárias/química , Biodegradação Ambiental , Catálise
17.
Enzyme Microb Technol ; 149: 109856, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34311893

RESUMO

Plants like almost all living organisms, have developed a biological clock or circadian clock (CC) capable of synchronizing and adjusting various metabolic and physiological processes at certain times of the day and in a period of 24 h. This endogenous timekeeping is able to predict the environmental changes providing adaptive advantages against stressful conditions. Therefore, the aim of this work was to analyze the possible link between metabolism of xenobiotic compounds (MXC) and the CC. Synchronized Nicotiana tabacum hairy roots (HRs) were used as a validated plant model system, and peroxidases (PODs), key enzymes of the phase I in the MCX, were evaluated after phenol treatment. Two POD genes were selected and their temporal expression profiles as well as the total POD activity were analyzed in order to find circadian oscillations either under control conditions or phenol treatment. It was demonstrated that these PODs genes showed oscillatory profiles with an ultradian period (period length shorter than the circadian period), and preserving the same phases and expression peaks still under phenol treatment. The total PODs activity showed also a marked oscillatory behavior mainly in phenol-treated HRs with the highest levels at ZT23. Untreated HRs showed decrease and increase in the intensity of some basic isoforms at light and dark phase, respectively, while in phenol- treated HRs, an increase in the intensity of almost all isoforms was observed, mainly during the dark phase, being coincident with the high PODs activity detected at ZT23. The periodic analysis determined an ultradian period either in total POD activity or in the POD activity of isoform VI, being 18.7 and 15.3 h, respectively. Curiously, in phenol treated HRs, the period length of total POD activity was longer than in untreated HRs, suggesting that phenol could induce a marked oscillatory behavior in the POD activity with better performance during the dark phase, which explain the higher phenol removal efficiencies at ZT23. These findings showed novel information about the performance of PODs, which would be rhythmically controlled at biochemical level, by phenol exposure.


Assuntos
Fenol , Tabaco , Peroxidases/genética , Fenóis , Raízes de Plantas
18.
Biosensors (Basel) ; 11(6)2021 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-34200755

RESUMO

Prussian blue analogs (PBAs) are well-known artificial enzymes with peroxidase (PO)-like activity. PBAs have a high potential for applications in scientific investigations, industry, ecology and medicine. Being stable and both catalytically and electrochemically active, PBAs are promising in the construction of biosensors and biofuel cells. The "green" synthesis of PO-like PBAs using oxido-reductase flavocytochrome b2 is described in this study. When immobilized on graphite electrodes (GEs), the obtained green-synthesized PBAs or hexacyanoferrates (gHCFs) of transition and noble metals produced amperometric signals in response to H2O2. HCFs of copper, iron, palladium and other metals were synthesized and characterized by structure, size, catalytic properties and electro-mediator activities. The gCuHCF, as the most effective PO mimetic with a flower-like micro/nano superstructure, was used as an H2O2-sensitive platform for the development of a glucose oxidase (GO)-based biosensor. The GO/gCuHCF/GE biosensor exhibited high sensitivity (710 A M-1m-2), a broad linear range and good selectivity when tested on real samples of fruit juices. We propose that the gCuHCF and other gHCFs synthesized via enzymes may be used as artificial POs in amperometric oxidase-based (bio)sensors.


Assuntos
Técnicas Biossensoriais , Ferrocianetos/química , Peroxidase/análise , Fontes de Energia Bioelétrica , Eletroquímica , Eletrodos , Enzimas Imobilizadas , Glucose , Glucose Oxidase , Grafite , Peróxido de Hidrogênio , Oxirredutases , Paládio , Peroxidases
19.
Arch Biochem Biophys ; 709: 108980, 2021 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-34224685

RESUMO

Cytochrome c (Cytc) is a multifunctional protein associated with electron shuttling in the inner membrane of mitochondria and also involving in the apoptotic pathway. It has been identified that mutations located in the flexible central 40-57 Ω-loop including the naturally occurring G41S, Y48H, and A51V mutants, which are found in patients with thrombocytopenia 4, a platelet disorder, alter the structural properties of human Cytc (hCytc) that associated to enhanced peroxidase activity. In this work we compared the cysteine-directed mutants of hCytc located in three different parts of Ω-loops, i.e., T28C and G34C (proximal Ω-loop), and A50C (central Ω-loop), with respect to the wild-type (WT) hCytc. The mutants and WT hCytc were structurally characterized by circular dichroism, heating and chemical denaturations, and fluorescence spectroscopy. The flexibility at the cysteine mutated sites was directly determined by site-directed spin-labeling Electron Spin Resonance. Alkaline transitions were determined by pH titration and the alkaline conformers were related to peroxidase activity of all hCytc proteins. Structural and dynamic characterizations were rationally correlated to the modulation of peroxidase activity in these mutants in comparison to the WT hCytc. We found that the cysteine mutations at residues T28 and G34, both located in the same region of Ω-loop, developed different conformations and dynamical properties that lead to different effects on the rates of peroxidase activity (G34C was ~2.6 folds higher), whereas the rate of G34C was closer to that of A50C mutant. The results implied that the flexibility and local structures of the proximal Ω-loop could also play an important role in modulating the peroxidase activity which can be associated to apoptosis.


Assuntos
Cisteína/química , Citocromos c/química , Peroxidases/química , Citocromos c/genética , Humanos , Cinética , Mutagênese Sítio-Dirigida , Mutação , Peroxidases/genética , Desnaturação Proteica , Estabilidade Proteica , Estrutura Secundária de Proteína
20.
J Environ Manage ; 296: 113163, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34229137

RESUMO

This work reports an environmentally benign and readily scalable process for production of akaganéite (ß-FeOOH) nanocomposites by using abundant gallic acid or grape seed tannins and urea. Influences from those phytochemicals on the properties of ß-FeOOH nanocomposites were investigated by X-ray powder diffraction, Fourier transform infrared spectroscopy, Thermogravimetric analysis, Scanning electron microscopy, Transmission electron microscopy, UV-Vis spectroscopy and Photoluminescence. The addition of 0.1% (w/v) grape seed tannins or gallic acid (640 mg L-1) solution yielded single-crystalline ß-FeOOH nanocomposites with reduced dimensions, increased porosities and BET surface area, and no oxidized impurities such as hematite (Fe2O3) were formed. The added grape seed tannins (S0.8) or gallic acid together with less urea (0.8 M) produced ß-FeOOH nanocomposites with higher activities as peroxidase mimics compared to those prepared with only urea (C0.8). Moreover, S0.8 was more efficient in methylene blue (MB) discoloration compared to C0.8 at all three pH values of 4, 7 and 11, and the S0.8-mediated MB degradation pathways at pH 4 and 7 were different from those at pH 11 due to the generation of different predominant oxidants. The overall MB discoloration efficacies by S0.8 at pH 4, 7 and 11 were combinative effects of both physical adsorption and chemical reactions. These ß-FeOOH nanocomposites possess great potential as peroxidase mimics for facile monitoring of excess hydrogen peroxide and applications in environmental remediation.


Assuntos
Azul de Metileno , Nanocompostos , Compostos Férricos , Peroxidase , Peroxidases
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