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1.
Food Chem ; 308: 125665, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-31655473

RESUMO

The effects of different dissolved oxygen concentrations (DOC) on the browning degree, amino acids, total phenols, reducing sugars, polyphenoloxidase (PPO), peroxidase (POD), phenylalanine ammonia-lyase (PAL) of pear wine, and the relationship between various quality indicators and browning degree were investigated. Dynamic model fitting analysis of the changes of physiochemical indicators of pear wine in the storage process were performed. The importance of the physiochemical indicators effect on the browning of pear wine during the storage process was analyzed by OPLS (orthogonal partial least squares discriminant analysis), and the effect of dissolved oxygen on the browning of pear wine was systematically revealed. The results showed that dissolved oxygen, total phenols and amino acids had the greatest influence on the browning degree of pear wine. It provided a theoretical basis for revealing the browning mechanism and inhibiting the browning of pear wine.


Assuntos
Pyrus/metabolismo , Vinho/análise , Aminoácidos/metabolismo , Catecol Oxidase/metabolismo , Fermentação , Frutas/química , Frutas/metabolismo , Oxirredutases/metabolismo , Peroxidase/metabolismo , Fenóis/metabolismo , Fenilalanina Amônia-Liase/metabolismo , Pyrus/química
2.
Food Chem ; 307: 125549, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31648175

RESUMO

The aim of this study was to determine the influence of static and multi-pulsed hydrostatic pressure processing (HPP) treatments on the polyphenolic profile, oxidoreductase activity, colour, and browning index of carrot juice. Phenolic acids, flavonoids, lignans and other polyphenols were the predominant polyphenols detected with Triple-TOF-LC-MS/MS. The highest concentration of ferulic acid, didymin, dihydro-p-coumaric acid, sesaminol and matairesinol isomers were found among all the compounds detected. After HPP treatment, irrespective of the pressures applied, new simple polyphenols like oleuropein, 4-vinylsyringol, isocoumarin, and 4-hydroxybenzaldehyde were detected. Both phenomena could be attributed to the release of bounded phenolic compounds after applying HPP, as well as enzymatic degradation and/or condensation. The highest inactivation of polyphenoloxidase (PPO) enzymes (57%) was obtained at 300 MPa × 3 pulses, and peroxidase (POD) enzymes (31%) at 600 MPa working in static mode. Significant changes in the colour parameters and browning index were observed in all HPP-treated juices.


Assuntos
Catecol Oxidase/metabolismo , Daucus carota/química , Polifenóis/análise , Pressão Sanguínea , Cromatografia Líquida , Cor , Daucus carota/enzimologia , Espectrometria de Massas em Tandem
3.
Food Chem ; 306: 125634, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31614291

RESUMO

The effects of postharvest treatments with γ-aminobutyric acid (GABA), methyl jasmonate (MeJA) or methyl salicylate (MeSA) on antioxidant systems and sensory quality of blood oranges during cold storage were evaluated (150 days at 3 °C plus 2 days at 20 °C, shelf life). Fruit firmness, titratable acidity (TA), total antioxidant activity (TAA) and ascorbic acid (AA) decreased during cold storage, all these changes being delayed in treated fruit, with the greatest differences observed with the 50 µmol L-1 MeJA and 100 µmol L-1 MeSA treatments. Total phenolic content (TPC), total anthocyanin content (TAC) and the major individual anthocyanins, cyanidin 3-glucoside and cyanidin 3-(6″-malonylglucoside), were found at higher concentration in treated fruit than in control during the whole cold storage period. Overall, 100 µmol L-1 MeSA was the most effective for maintaining fruit quality and maintained higher anthocyanin concentration due to higher phenylalanine ammonia-lyase (PAL) and lower polyphenol oxidase (PPO) activities.


Assuntos
Acetatos/farmacologia , Citrus sinensis/metabolismo , Ciclopentanos/farmacologia , Conservação de Alimentos , Oxilipinas/farmacologia , Salicilatos/farmacologia , Ácido gama-Aminobutírico/farmacologia , Antocianinas/metabolismo , Catecol Oxidase/metabolismo , Citrus sinensis/química , Citrus sinensis/efeitos dos fármacos , Temperatura Baixa , Frutas/química , Frutas/metabolismo , Glucosídeos/metabolismo , Valor Nutritivo , Fenilalanina Amônia-Liase/metabolismo
4.
Chem Asian J ; 14(21): 3898-3914, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31545553

RESUMO

Simultaneous incorporation of both CoII and CoIII ions within a new thioether S-bearing phenol-based ligand system, H3 L (2,6-bis-[{2-(2-hydroxyethylthio)ethylimino}methyl]-4-methylphenol) formed [Co5 ] aggregates [CoII CoIII 4 L2 (µ-OH)2 (µ1,3 -O2 CCH3 )2 ](ClO4 )4 ⋅H2 O (1) and [CoII CoIII 4 L2 (µ-OH)2 (µ1,3 -O2 CC2 H5 )2 ](ClO4 )4 ⋅H2 O (2). The magnetic studies revealed axial zero-field splitting (ZFS) parameter, D/hc=-23.6 and -24.3 cm-1 , and E/D=0.03 and 0.00, respectively for 1 and 2. Dynamic magnetic data confirmed the complexes as SIMs with Ueff /kB =30 K (1) and 33 K (2), and τ0 =9.1×10-8  s (1), and 4.3×10-8  s (2). The larger atomic radius of S compared to N gave rise to less variation in the distortion of tetrahedral geometry around central CoII centers, thus affecting the D and Ueff /kB values. Theoretical studies also support the experimental findings and reveal the origin of the anisotropy parameters. In solutions, both 1 and 2 which produce {CoIII 2 (µ-L)} units, display solvent-dependent catechol oxidation behavior toward 3,5-di-tert-butylcatechol in air. The presence of an adjacent CoIII ion tends to assist the electron transfer from the substrate to the metal ion center, enhancing the catalytic oxidation rate.


Assuntos
Catecol Oxidase/química , Cobalto/química , Complexos de Coordenação/síntese química , Sulfetos/química , Enxofre/química , Catecol Oxidase/metabolismo , Cobalto/metabolismo , Complexos de Coordenação/química , Complexos de Coordenação/metabolismo , Cristalografia por Raios X , Peróxido de Hidrogênio/análise , Cinética , Ligantes , Campos Magnéticos , Modelos Moleculares , Estrutura Molecular , Oxirredução , Sulfetos/metabolismo , Enxofre/metabolismo
5.
Insect Biochem Mol Biol ; 114: 103231, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31479697

RESUMO

Mycoplasmas, the smallest self-replicating organisms, are unique in that they lack cell walls but possess distinctive plasma membranes containing sterol acquired from their growth environment. Although mycoplasmas are known to be successful pathogens in a wide range of animal hosts, including humans, the molecular basis for their virulence and interaction with the host immune systems remains largely unknown. This study was conducted to elucidate the biochemical relationship between mycoplasma and the insect immune system. We investigated defense reactions of Tenebrio molitor that were activated in response to infection with Mycoplasma pulmonis. The results revealed that T. molitor larvae were more resistant to mycoplasma infection than normal bacteria equipped with cell walls. Intruding M. pulmonis cells were effectively killed by toxins generated from activation of the proPO cascade in hemolymph, but not by cellular reactions or antimicrobial peptides. It was determined that these different anti-mycoplasma effects of T. molitor immune components were primarily attributable to surface molecules of M. pulmonis such as phospholipids occurring in the outer leaflet of the membrane lipid bilayer. While phosphatidylcholine, a phospholipid derived from the growth environment, contributed to the resistance of M. pulmonis against antimicrobial peptides produced by T. molitor, phosphatidylglycerol was responsible for triggering activation of the proPO cascade.


Assuntos
Interações Hospedeiro-Patógeno/imunologia , Mycoplasma pulmonis/fisiologia , Tenebrio/imunologia , Animais , Peptídeos Catiônicos Antimicrobianos/sangue , Catecol Oxidase/metabolismo , Precursores Enzimáticos/metabolismo , Larva/imunologia , Larva/microbiologia , Fagocitose , Fosfolipídeos/imunologia , Tenebrio/microbiologia
6.
Food Chem ; 301: 125287, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31387048

RESUMO

The surface browning usually occurs on fresh-cut potato during storage. The effect of short-time high oxygen pretreatment on anti-browning of fresh-cut potato slices was investigated. The whole potato tubers were firstly immersed in the oxygen concentration of 21%, 60% and 80% for 20 min. Then, the potatoes were peeled, cut and stored at 4 °C for 8 days. The results showed that the short-time 80% oxygen pretreatment possessed significantly anti-browning effect by retarding the increase of polyphenol oxidase (PPO) activity and the accumulation of malondialdehyde (MDA) content, maintaining the cell integrity. Meanwhile, the 80% oxygen treatment could increase the activities of phenylalanine ammonia lyase (PAL) and peroxidase (POD), and the total phenolic content. Importantly, the 80% oxygen treatment could effectively improve the antioxidant capacity. Overall, all results suggest that the short-time high oxygen pretreatment holds great promise on anti-browning of fresh-cut potato.


Assuntos
Catecol Oxidase/metabolismo , Manipulação de Alimentos , Oxigênio/química , Peroxidase/metabolismo , Fenilalanina Amônia-Liase/metabolismo , Solanum tuberosum/enzimologia , Antioxidantes/análise , Malondialdeído/análise , Oxirredução , Oxigênio/farmacologia , Fenóis/metabolismo , Tubérculos/efeitos dos fármacos , Tubérculos/enzimologia , Solanum tuberosum/efeitos dos fármacos
7.
J Chem Ecol ; 45(8): 693-707, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31367970

RESUMO

Crop domestication and selective breeding have altered plant defense mechanisms, influencing insect-plant interactions. A reduction in plant resistance/tolerance against herbivory is generally expected in domesticated species, however, limited efforts have been made to compare inducibility of plant defenses between wild and domesticated genotypes. In the present study, the inducibility of several plant defense mechanisms (e.g. defensive chemicals, trichomes, plant volatiles) were investigated, and the performance and preference of the herbivore Helicoverpa zea were measured in three different tomato genotypes; a) wild tomato, Solanum pimpinellifolium L. (accession LA 2093), b) cherry tomato, S. lycopersicum L. var. cerasiforme (accession Matts Wild Cherry), and c) cultivated tomato, S. lycopersicum L. var. Better Boy). Enhanced inducibility of defensive chemicals, trichomes, and plant volatiles in the cultivated tomato, and a higher level of constitutive plant resistance against herbivory in the wild genotype was observed. When comparing the responses of damaged vs. undamaged leaves, the percent reduction in larval growth was higher on damaged leaves from cultivated tomato, suggesting a higher induced resistance compared to other two genotypes. While all tomato genotypes exhibited increased volatile organic compound (VOCs) emissions in response to herbivory, the cultivated variety responded with generally higher levels of VOCs. Differences in VOC patterns may have influenced the ovipositional preferences, as H. zea female moths significantly preferred laying eggs on the cultivated versus the wild tomato genotypes. Selection of traits during domestication and selective breeding could alter allocation of resources, where plants selected for higher yield performance would allocate resources to defense only when attacked.


Assuntos
Lycopersicon esculentum/química , Mariposas/fisiologia , Solanum/química , Animais , Comportamento Animal/efeitos dos fármacos , Catecol Oxidase/metabolismo , Feminino , Genótipo , Herbivoria , Larva/fisiologia , Lycopersicon esculentum/genética , Lycopersicon esculentum/metabolismo , Oviposição/efeitos dos fármacos , Fenóis/análise , Folhas de Planta/química , Folhas de Planta/metabolismo , Folhas de Planta/parasitologia , Proteínas de Plantas/análise , Análise de Componente Principal , Inibidores de Proteases/química , Solanum/genética , Solanum/metabolismo , Compostos Orgânicos Voláteis/química , Compostos Orgânicos Voláteis/metabolismo , Compostos Orgânicos Voláteis/farmacologia
8.
Food Chem ; 298: 124980, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31260963

RESUMO

Effect of phlorotannins (PT) treatments on the ployhenoloxidase (PPO) activity and quality changes of Pacific white shrimp during a 16-day period of storage in ice were studied. Among seaweeds, Sargassum tenerimum had the highest amount of PT (10.00 mg phloroglucinol/g), PPO inhibitory activity (71.94%) and therefore selected for PT extraction. The shrimp treated with 5% PT (w/v) showed the least melanosis score, pH, TVB-N values and lipid oxidation among all treatments throughout the iced storage. Lower counts of mesophilic and psychrotrophic bacteria (1-2 log CFU/g) were obtained with 5% PT treatment compared to the control at the last day of storage (P < 0.05). Sensory evaluation proved that 5% PT treatment could cause a 4-days increase in the shelf-life of shrimp compared to the control, PT1% and PT2% treatments. Therefore, 5% phlorotannins from S. tenerimum could be used as a safe melanosis inhibitor for the treatment of shrimp.


Assuntos
Armazenamento de Alimentos/métodos , Penaeidae , Floroglucinol/farmacologia , Frutos do Mar , Animais , Bactérias/efeitos dos fármacos , Catecol Oxidase/antagonistas & inibidores , Catecol Oxidase/química , Catecol Oxidase/metabolismo , Microbiologia de Alimentos , Qualidade dos Alimentos , Gelo , Melanose , Oxirredução , Penaeidae/efeitos dos fármacos , Penaeidae/microbiologia , Sargassum/química , Frutos do Mar/microbiologia
9.
Food Chem ; 298: 125004, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31260986

RESUMO

There is general interest in strategies to control polyphenol oxidase (PPO)-initiated enzymatic browning because it is often associated with declining food quality. Cyclodextrins are cyclic glucan oligosaccharides that form inclusion complexes with a number of PPO substrates. This study focuses on the effect of ß-cyclodextrins (ßCyD) on PPO-catalyzed reactions. Potato enzyme extracts and semi-purified potato PPO served as enzyme sources. Substrates included phenolics endogenous to potatoes. Reaction time-courses were followed spectrophotometrically; rates were compared by analysis of variance. Extents of ßCyD inhibition of PPO-catalyzed reactions are shown to be substrate specific and can be quantitatively accounted for based on degrees of ßCyD substrate sequestration. There was no evidence for direct irreversible ßCyD inactivation of potato PPO. An apparent "direct PPO inactivation" by ßCyD is shown to result from a sequence of sequestration-dependent reactions that occur in commonly employed assay systems for the quantification of PPO in fruits and vegetables.


Assuntos
Catecol Oxidase/química , Catecol Oxidase/metabolismo , Solanum tuberosum/enzimologia , beta-Ciclodextrinas/química , Catálise , Catecol Oxidase/antagonistas & inibidores , Fenóis/química , Fenóis/metabolismo , Proteínas de Plantas/antagonistas & inibidores , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Especificidade por Substrato , beta-Ciclodextrinas/metabolismo
10.
Plant Physiol Biochem ; 141: 225-230, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31185367

RESUMO

The present study evaluated the role of nitric oxide (NO) in mediating adventitious root (AR) growth, lignification and related enzymatic changes in the hypocotyls of Vigna radiata. To meet the objectives, the changes in AR growth, lignin content, and the activities of enzymes-peroxidases, polyphenol oxidases, and phenylalanine ammonia lyases- with NO donor and its scavenger were monitored. Hypocotyls were cultivated in aqueous solution supplemented with different concentrations of SNP (sodium nitroprusside, NO donor compound) and its scavenging compound (2,4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; cPTIO). Specifically, at low concentrations, SNP induced AR growth, increased the total lignin content and altered the activities of related oxidoreductases- peroxidases, polyphenol oxidases and phenylalanine ammonia lyases- which are involved in lignin biosynthesis pathway. At higher concentrations, a decline in AR growth and lignification was noticed. We analysed the function of NO in AR formation by depleting the endogenous NO using scavenging compound cPTIO. Hypocotyls grown in a medium supplemented with scavenger cPTIO exhibited significant decline in AR growth and the activities of lignin synthesizing enzymes. Application of NO scavenger showed that stimulatory properties on root lignification may be owing to NO itself. In addition, changes in AR growth were significantly correlated with these modified biochemical activities. Our analysis revealed that NO supplementation induces prominent alterations in lignin level during AR formation and this might be due to an alteration in the activity of lignin biosynthetic enzymes, which further affected the polymerization of monolignols and AR growth.


Assuntos
Hipocótilo/enzimologia , Lignina/química , Óxido Nítrico/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Vigna/enzimologia , Catecol Oxidase/metabolismo , Oxirredutases/metabolismo , Peroxidase/metabolismo , Fenilalanina Amônia-Liase/metabolismo , Raízes de Plantas/enzimologia
11.
Enzyme Microb Technol ; 128: 34-39, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31186108

RESUMO

Utilization of polyphenol oxidases (laccase, tyrosinase) in biosensor technology is an efficient approach towards phenol detection, which is significant in numerous fields such as environmental monitoring, food industry etc. The use of crude extract instead of pure enzyme eliminates the need for costly and laborious processes of enzyme separation and purification. This study employs polyphenol oxidase extract, biosynthesized by white-rot fungi Trametes pubescens (TP) for the development of amperometric biosensors for catechol detection. The catalytic activity of the crude extract was firstly used to induce the bio-synthesis of conducting polymer - polypyrrole (Ppy), resulting in the self-encapsulation of the enzyme extract within the conducting material. The viability and biological integrity of the enzyme extract was preserved after the synthesis and was able to efficiently detect phenolic compounds such as catechol. Comparative evaluations between the biosynthesized Ppy based biosensor (bio-Ppy) and the biosensor based on bio-PPy with additional enzyme extract (bio-Ppy-TP) were performed. Lastly, the performance of these two biosensors was compared with that of a third one, based on chemically synthesized Ppy with enzyme extract (chem-Ppy-TP). All three types of biosensors proved high efficiency for catechol detection at low concentration (1-60 µM) and were employed for real sample detection in fruit wines showing linear correlation with the spectrophotometric results obtained with the Folin-Ciocalteau standard test.


Assuntos
Técnicas Biossensoriais/métodos , Catecol Oxidase/metabolismo , Catecóis/análise , Misturas Complexas/metabolismo , Enzimas Imobilizadas/metabolismo , Trametes/enzimologia , Misturas Complexas/isolamento & purificação , Polímeros , Pirróis
12.
Plant Physiol Biochem ; 142: 1-7, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31247444

RESUMO

Proline is one of the amino acids that compose proteins and has various roles under non-stress and stress conditions. In this study, we investigated the effect of proline on the growth and browning of two plants, tobacco and rice, by exogenous application and endogenous increase of proline. Exogenous proline had a different effect on the growth and browning between tobacco and rice: proline affected negatively the growth of tobacco seedlings and favorably that of rice seedlings. In addition, proline prevented browning only in rice cultured cells, consistent with the increase of proline contents, but not in tobacco BY-2 cells. These results might be due to the difference of exogenous proline uptake activity in these cells. From the Lineweaver-Burk plots, proline inhibited polyphenol oxidase activity in vitro, which is a major factor of enzymatic browning in plants, by affecting the enzyme-substrate complex. Proline could suppress the browning of the plant callus by inhibition of PPO activity.


Assuntos
Oryza/efeitos dos fármacos , Oryza/crescimento & desenvolvimento , Prolina/farmacologia , Tabaco/efeitos dos fármacos , Tabaco/crescimento & desenvolvimento , Catecol Oxidase/antagonistas & inibidores , Catecol Oxidase/metabolismo , Células Cultivadas , Malondialdeído/metabolismo , Oryza/citologia , Oryza/genética , Proteínas de Plantas/antagonistas & inibidores , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Polifenóis/metabolismo , Prolina/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento
13.
Parasit Vectors ; 12(1): 219, 2019 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-31068226

RESUMO

BACKGROUND: Little is known about how human disease vectors will modify their life history patterns and survival capacity as a result of climate change. One case is that of Chagas disease, which has triatomine bugs and Trypanosoma cruzi as vectors and parasite, respectively. This work aimed to determine: (i) the activity of the prophenoloxidase system (prophenoloxidase and phenoloxidase activity, two indicators of immune ability) in three intestine regions (anterior midgut, posterior midgutand rectum) of the triatomine bug Meccus pallidipennis under three temperature conditions (20 °C, 30 °C and 34 °C) against two T. cruzi strains [ITRI/MX/14/CHIL (Chilpancingo) and ITRI/MX/12/MOR (Morelos)], and (ii) whether vector survival varies under these three temperatures after infection by these T. cruzi strains. RESULTS: Our results indicate that prophenoloxidase activity was lower at higher temperatures, that the level of prophenoloxidase activity elicited by each strain was different (higher in Chilpancingo than in Morelos strains), and that prophenoloxidase activity was more intense in the anterior midgut than in the posterior midgut or rectum. Survival rates were lower in insects maintained at higher temperatures and infected by Chilpancingo strains. CONCLUSIONS: These results indicate that climate change could lead to lower prophenoloxidase activity and survival rates in triatomines when infected with different T. cruzi strains, which could reduce the vector capacity of M. pallidipennis.


Assuntos
Catecol Oxidase/metabolismo , Mudança Climática , Precursores Enzimáticos/metabolismo , Temperatura Ambiente , Triatoma/parasitologia , Trypanosoma cruzi/fisiologia , Animais , Feminino , Trato Gastrointestinal/anatomia & histologia , Trato Gastrointestinal/parasitologia , Insetos Vetores/enzimologia , Insetos Vetores/parasitologia , Masculino , Triatoma/enzimologia
14.
Molecules ; 24(10)2019 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-31109085

RESUMO

Apart from non-enzymatic browning, polyphenol oxidase (PPO) also plays a role in the browning reaction of orange (Citrus sinensis Osbeck) juice, and needs to be inactivated during the processing. In this study, the protein with high PPO activity was purified from orange (Citrus sinensis Osbeck) and inactivated by ultrasonic processing. Fluorescence spectroscopy, circular dichroism (CD) and Dynamic light scattering (DLS) were used to investigate the ultrasonic effect on PPO activity and structural changes on purified PPO. DLS analysis illustrated that ultrasonic processing leads to initial dissociation and final aggregation of the protein. Fluorescence spectroscopy analysis showed the decrease in fluorescence intensity leading to the exposure of Trp residues to the polar environment, thereby causing the disruption of the tertiary structure after ultrasonic processing. Loss of α-helix conformation leading to the reorganization of secondary structure was triggered after the ultrasonic processing, according to CD analysis. Ultrasonic processing could induce aggregation and modification in the tertiary and secondary structure of a protein containing high PPO activity in orange (Citrus sinensis Osbeck), thereby causing inactivation of the enzyme.


Assuntos
Catecol Oxidase/química , Citrus sinensis/química , Proteínas de Plantas/química , Conformação Proteica/efeitos da radiação , Ondas Ultrassônicas , Catecol Oxidase/isolamento & purificação , Catecol Oxidase/metabolismo , Dicroísmo Circular , Citrus sinensis/enzimologia , Ativação Enzimática , Reação de Maillard , Peso Molecular , Tamanho da Partícula , Proteínas de Plantas/isolamento & purificação , Proteínas de Plantas/metabolismo , Análise Espectral
15.
Int J Mol Sci ; 20(10)2019 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-31137877

RESUMO

The aim of this study was to determine how the mulberry (Morus notabilis) polyphenol oxidase 1 gene (MnPPO1) is regulated during plant stress responses by exploring the interaction between its promoter region and regulatory transcription factors. First, we analyzed the cis-acting elements in the MnPPO1 promoter. Then, we used the MnPPO1 promoter region [(1268 bp, including an MYB3R-binding cis-element (MSA)] as a probe to capture proteins in DNA pull-down assays. These analyses revealed that the MYB3R1 transcription factor in M. notabilis (encoded by MnMYB3R1) binds to the MnPPO1 promoter region. We further explored the interaction between the MnPPO1 promoter and MYB3R1 with the dual luciferase reporter, yeast one-hybrid, and chromatin immunoprecipitation assays. These analyses verified that MnMYB3R1 binds to the MSA in the MnPPO1 promoter region. The overexpression of MnMYB3R1 in tobacco upregulated the expression of the tobacco PPO gene. This observation as well as the quantitative real-time PCR results implied that MnMYB3R1 and PPO are involved in the abscisic acid-responsive stress response pathway.


Assuntos
Catecol Oxidase/genética , Morus/genética , Proteínas de Plantas/metabolismo , Fatores de Transcrição/metabolismo , Catecol Oxidase/metabolismo , Regulação da Expressão Gênica de Plantas , Morus/metabolismo , Regiões Promotoras Genéticas , Ligação Proteica
16.
J Chem Ecol ; 45(5-6): 515-524, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31127421

RESUMO

Although the tritrophic interactions of plants, insect herbivores and their natural enemies have been intensely studied for several decades, the roles of entomopathogens in their indirect modulation of plant-insect relationships is still unclear. Here, we employed a sublethal dose of a baculovirus with a relatively broad host range (AcMNPV) to explore if feeding by baculovirus-challenged Helicoverpa zea caterpillars induces direct defenses in the tomato plant. We examined induction of plant defenses following feeding by H. zea, including tomato plants fed on by healthy caterpillars, AcMNPV-challenged caterpillars, or undamaged controls, and subsequently compared the transcript levels of defense related proteins (i.e., trypsin proteinase inhibitors, peroxidase and polyphenol oxidase) and other defense genes (i.e., proteinase inhibitor II and cysteine proteinase inhibitor) from these plants, in addition to comparing caterpillar relative growth rates. As a result, AcMNPV-challenged caterpillars induced the highest plant anti-herbivore defenses. We examined several elicitors and effectors in the secretions of these caterpillars (i.e., glucose oxidase, phospholipase C, and ATPase hydrolysis), which surprisingly did not differ between treatments. Hence, we suggest that the greater induction of plant defenses by the virus-challenged caterpillars may be due to differences in the amount of these secretions deposited during feeding or to some other unknown factor(s).


Assuntos
Baculoviridae/patogenicidade , Lycopersicon esculentum/metabolismo , Mariposas/fisiologia , Animais , Catecol Oxidase/genética , Catecol Oxidase/metabolismo , Comportamento Alimentar , Regulação da Expressão Gênica de Plantas , Herbivoria , Interações Hospedeiro-Parasita , Larva/efeitos dos fármacos , Larva/fisiologia , Larva/virologia , Lycopersicon esculentum/parasitologia , Mariposas/crescimento & desenvolvimento , Mariposas/virologia , Peroxidase/genética , Peroxidase/metabolismo , Folhas de Planta/metabolismo , Folhas de Planta/parasitologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , RNA de Plantas/isolamento & purificação , RNA de Plantas/metabolismo , Glândulas Salivares/metabolismo
17.
J Food Sci ; 84(5): 1078-1086, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30958915

RESUMO

Distribution of polyphenoloxidase (PPO) from different anatomical parts of Pacific white shrimp was examined. Among all parts, cephalothorax possessed the maximal PPO activity (P < 0.05), followed by pereopods, telson, pleopods, carapace, cuticle, and muscle, respectively. The higher PPO activity in cephalothorax was in line with the greater melanosis in this part during chilled storage. According to activity-staining toward 3,4-dihydroxy-ʟ-phenylalanine (ʟ-DOPA), PPO exhibited an activity band with a molecular weight (MW) of 210 kDa. When cephalothorax PPO was purified using ammonium sulfate precipitation and a series of chromatographic techniques, involving DEAE-Sepharose anion exchange and Sephadex G-75 gel filtration columns, homogeneity was obtained. Based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and native-PAGE, the Sephadex G-75 fraction showed a single band. The MW band on SDS-PAGE and gel filtration was estimated as 210 kDa, suggesting a monomeric molecule. For the inhibitor study, cysteine and 4-hexylresorcinol showed competitive inhibition toward PPO, while epigallocatechin gallate and kojic acid demonstrated mixed-type inhibition toward PPO. PRACTICAL APPLICATION: Melanosis (black spot formation) triggered by polyphenoloxidase (PPO) drastically reduces the shelf-life of shrimp. PPO was localized in several anatomical parts of Pacific white shrimp with varying activities. Certain compounds, including cysteine, 4-hexylresorcinol, epigallocatechin gallate, and kojic acid, showed PPO inhibitory activity with different modes of inhibition. The obtained information provided a promising method for manufacturers to keep the prime eating quality of Pacific white shrimp throughout postmortem transportation and storage using selected PPO inhibitors.


Assuntos
Catecol Oxidase , Penaeidae/enzimologia , Alimentos Marinhos/análise , Animais , Catecol Oxidase/análise , Catecol Oxidase/química , Catecol Oxidase/metabolismo , Distribuição Tecidual
18.
J Food Sci ; 84(5): 1122-1128, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30997932

RESUMO

This study was conducted to examine the effects of microwave cold plasma (CP) treatment on inactivation of polyphenol oxidase (PPO) of potato. The PPO activity and treatment variables were fit to first-order kinetics, the Weibull model, and the second-order model. The optimum CP-generation power and treatment time for inactivating PPO in the PPO extract were found to be 900 W and 40 min, respectively, which resulted in the highest inactivation of PPO (49.5%). PPO activity after CP treatment of potato slices decreased from 72.4% to 59.0% as the sample surface-to-volume ratio increased from 7.1 to 9.0. CP treatment delayed the browning of potato slices. Microwave CP treatment effectively inactivated PPO in potatoes, demonstrating the potential of CP treatment for controlling PPO activity in foods. PRACTICAL APPLICATION: This study demonstrated that microwave CP treatment, a nonthermal food processing technology, inactivates PPO activity in potatoes. The results showed that the inactivation effect of CP treatment on PPO corresponded to the surface-to-volume ratio of potato slices. Furthermore, this study proposed an enzyme inactivation model that is suitable for predicting the inactivation of PPO activity and confirmed that CP treatment delayed browning in potatoes.


Assuntos
Catecol Oxidase , Manipulação de Alimentos/métodos , Proteínas de Plantas , Gases em Plasma , Solanum tuberosum/enzimologia , Catecol Oxidase/química , Catecol Oxidase/efeitos dos fármacos , Catecol Oxidase/metabolismo , Estabilidade Enzimática , Micro-Ondas , Proteínas de Plantas/química , Proteínas de Plantas/efeitos dos fármacos , Proteínas de Plantas/metabolismo , Gases em Plasma/química , Gases em Plasma/metabolismo , Gases em Plasma/farmacologia
19.
PLoS One ; 14(4): e0215540, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30998725

RESUMO

The phenolic composition and content of olive fruit are some of the attributes that determine oil quality. This composition depends on the olive variety, the cultivation system, and the fruit's ripeness. This study considered two olive varieties (Manzanilla and Morisca), under two water regimes (irrigated and rainfed), harvested at three stages of maturation (S1, S2, and S3), over three consecutive campaigns (2011, 2012, and 2013). The accumulation of phenols in the fruit was found to depend only on the stage of ripeness, while the flavonoid and phenylpropanoid contents depended also on the variety and the water regime. Superoxide dismutase (SOD) activity was linked to O2- production, which in turn depended on water regime, variety, and stage of maturation (this last being a process involving ROS). The peroxidase (POX) activity seemed only to depend on ripeness, while polyphenol oxidase (PPO) activity varied from year to year as well as presenting a strong ripeness dependence that was in clear coherence with the levels of phenolic compounds that the olives accumulate. All these relationships between the variables and the factors conform a dataset with the structure of a multidimensional array that is difficult to interpret using conventional techniques of statistical analysis. This work takes a novel approach (MultiDimensional Scaling associated with a Partial Triadic Analysis, MDS-PTA) to the analysis of this type of data structure which allows its correct interpretation. The analysis showed that the state of maturation of the olives is the most clearly discriminating factor, far more so than the cultivar, water regime, or year. Thus, the phenols and the total antioxidant activity (FRAP) showed strong clustering, being closely related in all three years studied. The oxidant and antioxidant activities showed a certain tendency to cluster, although in these cases the year also had an influence as a factor, indicating that these parameters depend more on external factors and less on ripeness.


Assuntos
Antioxidantes/metabolismo , Frutas/crescimento & desenvolvimento , Olea/crescimento & desenvolvimento , Oxidantes/metabolismo , Catecol Oxidase/metabolismo , Flavonoides/metabolismo , Peroxidase/metabolismo , Proteínas de Plantas/metabolismo
20.
Int J Biol Macromol ; 134: 139-145, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31022487

RESUMO

Theaflavins (TFs) have attracted much attention due to their various bioactivities in black tea. This paper describes the first trial for enzymatic production of TFs by recombinant polyphenol oxidases (PPOs). PPO genes were cloned from nine species and expressed in E. coli. Crude enzyme assays by LC-MS revealed that eight recombinant PPOs were active for TFs production from tea polyphenols as substrates. Much higher activities were observed for crude enzymes of Md2 from Malus domestica (apple), Pp4 from Pyrus pashia (pear), and Ej2 from Eriobotrya japonica (loquat). When immobilized on mesoporous silica, crude Md2 was most active. The purified Md2 was immobilized and showed almost twice activity as high as its free enzyme. While the maximum activity of free enzyme was found at pH 5 and 10-30 °C, the immobilized enzyme had broader range of pH 4-6 and 10-40 °C. The activity of immobilized enzyme was relatively constant during the pH and thermal stability test. When used at 0.2 mg/ml in the beginning, the immobilized enzyme retained approximately 40% of its initial activity after 8 cycles of operation.


Assuntos
Biflavonoides/biossíntese , Catequina/biossíntese , Catecol Oxidase/metabolismo , Polifenóis/metabolismo , Proteínas Recombinantes , Chá/química , Biflavonoides/química , Catequina/química , Catecol Oxidase/genética , Ativação Enzimática , Estabilidade Enzimática , Fermentação , Concentração de Íons de Hidrogênio , Estrutura Molecular , Polifenóis/química , Termodinâmica
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