Journal articles on the topic 'Polyphenol oxidase activity (PPO)'
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Sabir, Dlawer M., and Basima Y. Putros. "The Role of Polyphenol Oxidase (PPO) in Antiprolactin Activity." Journal of Zankoy Sulaimani - Part A 7, no. 1 (May 28, 2003): 55–59. http://dx.doi.org/10.17656/jzs.10123.
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Escobar, Matthew A., Andrew Shilling, Pine Higgins, Sandra L. Uratsu, and Abhaya M. Dandekar. "Characterization of Polyphenol Oxidase from Walnut." Journal of the American Society for Horticultural Science 133, no. 6 (November 2008): 852–58. http://dx.doi.org/10.21273/jashs.133.6.852.
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The enzyme polyphenol oxidase (PPO) is nearly ubiquitous in Kingdom Plantae and catalyzes the oxidation of phenolic compounds into highly reactive quinones. Although the functional importance of PPO in plants remains uncertain, a putative antipathogen role for walnut (Juglans regia) PPO was posited as early as 1911. However, despite the rich diversity of phenolics present in walnut leaves and hulls, walnut PPO has been little studied since the early 1900s. We cloned a PPO-encoding gene from a walnut pistillate flower cDNA library and designated the gene jrPPO1. Genomic Southern analysis demonstrated that jrPPO1 is the sole PPO gene in walnut. Transgenic tobacco (Nicotiana tabacum) plants expressing jrPPO1 display greater than 10-fold increases in leaf PPO activity compared with wild-type tobacco, demonstrating that jrPPO1 encodes a functional enzyme. The jrPPO1 protein is expressed primarily in the leaves, hulls, and flowers of walnut trees and is not regulated by wounding or methyl jasmonate. To examine whether walnut PPO could affect pathogen resistance, tobacco plants expressing jrPPO1 were challenged with Pseudomonas syringae pv. tabaci. Based on both symptom development and quantitative analyses of bacterial growth in planta, the PPO-expressing plants did not display increased resistance to this pathogen. Leaf extract browning assays indicated that tobacco leaves lack the endogenous phenolic substrates required for significant jrPPO1 activity and quinone production in planta.
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Holderbaum, Daniel Ferreira, Tomoyuki Kon, Tsuyoshi Kudo, and Miguel Pedro Guerra. "Enzymatic Browning, Polyphenol Oxidase Activity, and Polyphenols in Four Apple Cultivars: Dynamics during Fruit Development." HortScience 45, no. 8 (August 2010): 1150–54. http://dx.doi.org/10.21273/hortsci.45.8.1150.
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Enzymatic browning is one of the most important reactions that occur in fruits and vegetables, usually resulting in negative effects on color, taste, flavor, and nutritional value. The reaction is a consequence of phenolic compounds' oxidation by polyphenol oxidase (PPO), which triggers the generation of dark pigments. This is particularly relevant for apples, which are rich in polyphenols and highly susceptible to enzymatic browning. The objective of the present work was to quantify enzymatic browning and PPO activity and identify and quantify target polyphenols in apple [Malus ×sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] pulp in the cultivars (cvs.) Aori27, Elstar, Fuji, and Mellow at three fruit developmental stages (FDS). The enzymatic browning was quantified by tristimulus colorimetry; PPO activity was quantified by an enzyme–substrate spectrophotometric assay; phenolic compounds were determined and quantified by reverse-phase high-performance liquid chromatography–ultraviolet/visible–mass spectrometry. Enzymatic browning showed significant difference among cvs. and FDSs and interaction between both factors. PPO activity showed significant difference among cultivars and FDSs. A significant difference was evidenced for polyphenol content among cultivars and FDSs with interaction between both factors. Chlorogenic acid was the major phenolic compound in ‘Aori27’ and ‘Mellow’. In ‘Fuji’, chlorogenic acid and (–)-epicatechin were the major phenolics and in ‘Elstar’ (–)-epicatechin and procyanidin B2 were the major phenolics at different FDSs. The enzymatic browning showed high correlation to polyphenol content in all cultivars and high correlation was observed between browning and PPO activity in ‘Aori27’ and ‘Elstar’. The magnitude of the correlation between browning and polyphenols and PPO activity is genotype-specific. At the commercial harvest, ‘Fuji’ showed the highest polyphenol content and ‘Aori27’ showed the lowest level for enzymatic browning. Chemical names used: 3-(3,4-dihydroxycinnamoyl) quinic acid (chlorogenic acid), (–)-cis-3,3′,4′,5,7-pentahydroxyflavane (epicatechin), and cis,cis″-4,8″-Bi(3,3′,4′,5,7-pentahydroxyflavane) (procyanidin B2).
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Lee, Jo-Won, Sohee Yoon, Y. Martin Lo, Haohao Wu, Sook-Young Lee, and BoKyung Moon. "Intrinsic polyphenol oxidase-like activity of gold@platinum nanoparticles." RSC Advances 5, no. 78 (2015): 63757–64. http://dx.doi.org/10.1039/c5ra07636f.
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Au@Pt NPs showed PPO mimetic activity over a wider range of pH and temperatures compared to PPO. In the oxidation of all substrates, Au@Pt NPs exhibited higher affinity to the substrates, especially to catechol and pyrogallol, compared with PPO.
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Okpuzor, J., and O. Omidiji. "Peroxidase-Polyphenol Oxidase Association in Dioscorea esculenta." Zeitschrift für Naturforschung C 53, no. 11-12 (December 1, 1998): 957–60. http://dx.doi.org/10.1515/znc-1998-11-1204.
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Abstract A crude enzyme extract from Dioscorea esculenta var. fasiculata tissue subjected to ion exchange chromatography on DEAE-Sephadex A-50 column. This proced ure resolved the extract into two main protein peaks one of which eluted through the column relatively unbound while the other protein peak which remained bound to the column was eluted with 1.0 ᴍ NaCl. Both protein peaks contained polyphenol oxidase (PPO) and peroxidase (POD) activities. The non-binding protein peak was resolved by gel filtration on Sephadex G-200 into distinct PPO and POD activities and by virtue of their apparent molecular weights of 95.5 Kd and 38.0 Kd for PPO and POD respectively were determined to be the typical enzymes. The PPO activity was completely inhibited invitro by 5 mᴍ polyvinyl pyrrolidone (PVP). The binding protein peak was not resolved by gel filtration. It contained PPO activity which was not inhibited by PVP and a POD activity which was completely inhibited by dithiothreitol (DTT) This ionic protein peak contained 60% of total POD in the tissue, has an apparent molecular weight of 56 Kd and is suggested to be a strongly anionic peroxidase which also exhibits polyphenol oxidase activity.
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Mccaig, T. N., D. Y. K. Fenn, R. E. Knox, R. M. Depauw, J. M. Clarke, and J. G. Mcleod. "Measuring polyphenol oxidase activity in a wheat breeding program." Canadian Journal of Plant Science 79, no. 4 (October 1, 1999): 507–14. http://dx.doi.org/10.4141/p98-135.
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High levels of polyphenol oxidase (PPO) have been associated with discoloration of end-use products of wheat, especially certain noodle types. Two whole-seed methods of measuring PPO, one based on 10 mM tyrosine as substrate and the other on 90 mM catechol, were examined and modified to determine their potential as screening tools in large-scale breeding programs. Thirteen spring wheat and two spring triticale genotypes were used to compare the methods. Both methods could measure PPO on individual seeds. All genotypes displayed large seed-to-seed variation for PPO with both substrates. The mean coefficient of variation for the PPO values of individual seeds within genotypes was 39% with tyrosine and 34% with catechol. Furthermore, the PPO values of individual seeds within genotypes were not normally distributed for most genotypes. Identifying genotypes with incremental improvements in PPO would probably require measurement of 70–100 seeds. Approximately 50% of the catecholase activity was associated with the water extract after soaking seeds for 16 h, while all of the tyrosinase activity was still associated with the seed, suggesting that different enzymes are responsible for oxidizing tyrosine and catechol in wheat. While the 10 mM tyrosine assay was nondestructive and allowed plants to be generated from seeds low in PPO, 90 mM catechol reduced germination to less than 20%. Reducing the catechol to 30 mM improved germination to 85%, did not substrate-limit the reaction, and reduced the health risk associated with the assay. Spectral and kinetic differences between the assays were also considered. Key words: Triticum sp., wheat, polyphenol oxidase, catechol, tyrosine
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Toro-Uribe, Said, Jhair Godoy-Chivatá, Arley René Villamizar-Jaimes, María de Jesús Perea-Flores, and Luis J. López-Giraldo. "Insight of Polyphenol Oxidase Enzyme Inhibition and Total Polyphenol Recovery from Cocoa Beans." Antioxidants 9, no. 6 (May 27, 2020): 458. http://dx.doi.org/10.3390/antiox9060458.
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A full factorial design (ascorbic acid/l-cysteine inhibitors, temperature, and time as factors) study was conducted to enhance inhibition of polyphenol oxidase (PPO) activity without decreasing cocoa polyphenol concentrations. The data obtained were modelled through a new equation, represented by Γ, which correlates both high polyphenol content with reduced specific PPO activity. At optimized values (70 mM inhibitory solution at 96 °C for 6.4 min, Γ = 11.6), 93.3% PPO inhibition and total polyphenol of 94.9 mg GAE/g were obtained. In addition, microscopy images confirmed the cell morphological changes measured as the fractal dimension and explained the possible cell lysis and denaturation as a result of heat treatment and chemical inhibitors. Results also showed that PPO enzyme was most suitable (higher vmax/Km ratio) for catechol, with a reduction in its affinity of 13.7-fold after the inhibition heat treatment. Overall, this work proposed a suitable and food-safe procedure for obtaining enriched polyphenol extract with low enzyme activity.
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E, Kale, and Yuzugullu Karakus Y. "Application of Aqueous Two-Phase System to the Purification of Persimmon Polyphenol Oxidase." Open Access Journal of Microbiology & Biotechnology 7, no. 3 (July 4, 2022): 1–7. http://dx.doi.org/10.23880/oajmb-16000232.
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Polyphenol oxidases (PPOs), which have recently become very popular among many researchers, catalyze the oxidation of phenolic compounds. Polyphenol oxidases are generally found in plants. Among them, persimmon (Diospyros kaki L.) is known as a good source for polyphenol oxidases. In this study, the polyphenol oxidase enzyme was purified from persimmon fruit using aqueous two-phase (ATPS). The optimized system was composed of 18% (w/w) PEG4000, 7% (w/w) NaH2 P04 and 1% (w/w) NaCl (pH 8.5, 25°C and 5 g). The PPO enzyme was obtained from the system by 4.8-fold purification with 191% activity recovery. The molecular weight of the enzyme, 28 kDa, was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. In summary, it has been shown that the PPO enzyme can be obtained from persimmon in a short time and at low cost using a non-chromatographic method-ATPS.
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Rathjen, H., and SP Robinson. "Characterisation of a Variegated Grapevine Mutant Showing Reduced Polyphenol Oxidase Activity." Functional Plant Biology 19, no. 1 (1992): 43. http://dx.doi.org/10.1071/pp9920043.
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Fruit of the variegated grapevine mutant Bruce's Sport is known to dry to a lighter colour than other seedless varieties. The biochemical basis for this decreased browning capacity was investigated. Bruce's Sport grapes had similar levels of phenolic compounds to Sultana H5. Activity of the enzyme polyphenol oxidase (PPO EC 1.10.3.1) in mature berries of Bruce's Sport was only 20-30% of that in Sultana H5. No evidence of inhibitors or activators of PPO was found when berry extracts were mixed. PPO activity on a fresh weight basis was highest in the grape seed traces, intermediate in the skin, and lowest in the pulp in both varieties. In each tissue type, however, PPO activity in Bruce's Sport was less than 25% of that in Sultana H5. On a fresh weight basis, PPO activity in Sultana H5 berries was high at fruit set then declined as the berry developed. PPO activity per berry increased from fruit set until veraison, then remained constant. PPO activity showed similar changes during development of Bruce's Sport berries but was lower than in Sultana H5 at all stages. The Bruce's Sport grapes were variegated and the green regions of skin had similar PPO activity to Sultana H5 skin while the white regions had very low activity. Only the green regions of skin of Bruce's Sport grapes stained for PPO activity with endogenous or exogenously applied phenolic substrates. The decreased browning in this grapevine mutant apparently results from decreased levels of PPO activity in the white regions of the berry, possibly arising from a disruption in chloroplast development.
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Demir, D., C. Eken, E. Çelik, and N. Alkan. "Effect of Rhizoctonia spp. on Polyphenol Oxidase Enzyme Activity in Alfalfa Seedling." Research Journal of Biotechnology 16, no. 11 (October 25, 2021): 47–50. http://dx.doi.org/10.25303/1611rjbt4750.
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Soil borne diseases cause significant losses on quantity and quality of many crop species annually. Rhizoctonia is a widespread and ecologically diverse soilborne fungus causing different types of diseases in many plant species including alfalfa (Medicago sativa). Rhizoctonia species have been traditionally identified based on the cell nuclear condition. Polyphenol oxidases (PPOs) are ubiquitous copper-containing enzymes that are widely occurring enzymes among plants. PPOs are involved in the oxidation of polyphenols into quinones (antimicrobial compounds) and lignification of plant cells that contribute to the formation of defense barriers against pathogens. The study was conducted with the aim to determine the effect of indigenous isolates of a multinucleate (Rhizoctonia solani AG-4) and nineteen isolates of binucleate Rhizoctonia on PPO activity in alfalfa (cv. Gea) seedling under in vitro conditions. The activity of PPO enzyme was determined in inoculated and uninoculated control alfalfa plants after ten days from inoculation. There was a significant increase in the activity of PPO after treatment of alfalfa seedling with isolates of Rhizoctonia. Among Rhizoctonia isolates, highest induction of PPO activity was recorded with pathogenic R. solani AG-4. In present study, increased amounts of PPO were also observed in plants that were challenged with Rhizoctonia spp. PPO has a role in catalyzing phenolic oxidation in limiting disease development. PPO may therefore be involved in induction of defense resistance against plant diseases.
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Yamasaki, Yoshiki, Haruyoshi Konno, and Kazuhiko Noda. "Polyphenol oxidase from wheat bran is a serpin." Acta Biochimica Polonica 55, no. 2 (May 26, 2008): 325–28. http://dx.doi.org/10.18388/abp.2008_3079.
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Polyphenol oxidase (PPO; EC 1.10.3.2) was isolated from wheat bran by a procedure that included ammonium sulfate fractionation, batch adsorption by DEAE-cellulofine, CM-cellulofine column chromatography, DEAE-cellulofine column chromatography, preparative isoelectric focusing, adsorption on the membrane of a Vivapure Q Maxi H spin column, and heat treatment. These procedures led to 150-fold purification with 4.2% recovery. The PPO was homogeneous by SDS/PAGE. The relative molecular weight of the PPO was estimated to be 37,000 based on its mobility in SDS/PAGE. The isoelectric point of the PPO was 4.4. The K(m) values of the PPO for caffeic acid, chlorogenic acid, pyrocatechol, 4-methyl catechol and l-DOPA as substrates were 0.077, 0.198, 1.176, 1.667 and 4.545 mM. The PPO was strongly inhibited by tropolone. The K(i) value for tropolone is 2.2 x 10(-7) M. The sequence of the 15 N-terminal amino-acid residues was determined to be ATDVRLSIAHQTRFA, which was identical to those of serpin from Triticum aestivum and protein Z from Hordeum vulgare. The PPO strongly inhibited the activity of trypsin, which is an enzyme of serine proteases; 50% inhibition was observed with 1.5 x 10(-7) M PPO. The K(i) value for PPO is 2.3 x 10(-8) M. The wheat bran PPO should be a very important protein for protecting wheat against disease, virus, insect and herbivore damages by both the activities of PPO and protease inhibitor.
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Stewart, Richard J., Brett J. B. Sawyer, Carolyn S. Bucheli, and Simon P. Robinson. "Polyphenol oxidase is induced by chilling and wounding in pineapple." Functional Plant Biology 28, no. 3 (2001): 181. http://dx.doi.org/10.1071/pp00094.
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Polyphenol oxidase (PPO) activity was found to be low in the leaves, roots, inflorescence tissues and developing and mature fruit of pineapple (Ananas comosus L.). In fruit affected by the chill-induced internal browning disorder known as Blackheart, PPO activity was 10-fold higher than in unaffected fruit, and there was a direct correlation between PPO activity and the severity of Blackheart symptoms. Degenerate oligonucleotide primers were designed to conserved regions of plant PPO genes, and used to amplify two distinct pineapple PPO cDNAs, designated PINPPO1 (2181 bp) and PINPPO2 (1319 bp), which share 81% sequence identity at the DNA level and show a high degree of homology to other plant PPO genes. PINPPO1 encodes a peptide of 604 amino acids, including a putative transit peptide of 95 amino acids and two copper-binding regions, CuA and CuB, which are highly conserved in plant PPOs. Southern analysis suggested the presence of at least four PPO genes in pineapple. Expression of PINPPO1 and PINPPO2 was low in roots, leaves, inflorescence tissues and developing fruit, but was strongly up-regulated in response to chilling and wounding. These results indicate that PPO is synthesised de novo in response to chilling of pineapple fruit, and implicate a role for the enzyme in the development of Blackheart disorder.
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Sánchez, Rosario, Laura Arroyo, Pilar Luaces, Carlos Sanz, and Ana Pérez. "Olive Polyphenol Oxidase Gene Family." International Journal of Molecular Sciences 24, no. 4 (February 6, 2023): 3233. http://dx.doi.org/10.3390/ijms24043233.
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The phenolic compounds containing hydroxytyrosol are the minor components of virgin olive oil (VOO) with the greatest impact on its functional properties and health benefits. Olive breeding for improving the phenolic composition of VOO is strongly dependent on the identification of the key genes determining the biosynthesis of these compounds in the olive fruit and also their transformation during the oil extraction process. In this work, olive polyphenol oxidase (PPO) genes have been identified and fully characterized in order to evaluate their specific role in the metabolism of hydroxytyrosol-derived compounds by combining gene expression analysis and metabolomics data. Four PPO genes have been identified, synthesized, cloned and expressed in Escherichia coli, and the functional identity of the recombinant proteins has been verified using olive phenolic substrates. Among the characterized genes, two stand out: (i) OePPO2 with its diphenolase activity, which is very active in the oxidative degradation of phenols during oil extraction and also seems to be highly involved in the natural defense mechanism in response to biotic stress, and (ii) OePPO3, which codes for a tyrosinase protein, having diphenolase but also monophenolase activity, which catalyzes the hydroxylation of tyrosol to form hydroxytyrosol.
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Wu, Xin-Ting, Xiao-Na Guo, and Ke-Xue Zhu. "Inhibition of L-Cysteine on the Browning of Fresh Wet Noodles." Foods 10, no. 6 (May 21, 2021): 1156. http://dx.doi.org/10.3390/foods10061156.
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This research explored the effect of L-cysteine on the browning of fresh wet noodles (FWN). With the increasing addition of L-cysteine (0.02–0.1%), the ΔL* decreased and Δa*, Δb* increased. The L-cysteine could reduce the pH value and polyphenol oxidase (PPO) activity and increase the retention rate of polyphenol of FWN. It suggested that L-cysteine could inhibit the browning of FWN by decreasing pH value, PPO activity, and the oxidation of polyphenols. In the in vitro PPO solution, the inhibitory effect of L-cysteine on PPO activity was related to the decrease in pH and the ability of chelating Cu2+. According to UPLC-TOF-MS analysis, L-cysteine could reduce the generation of browning products, which suggested that L-cysteine could react with the browning intermediate product (quinone) and generate a light-colored substance (-C9H10NO4S). L-cysteine effectively inhibited the browning of FWN and had the potential to be used in noodle industry.
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Gao, Lu, Yuan Yuan, Ying Chang Li, and Yin Xia Wei. "Study on Polyphenol Oxidase Activity in Different Parts of Purple Sweet Potato." Advanced Materials Research 898 (February 2014): 149–52. http://dx.doi.org/10.4028/www.scientific.net/amr.898.149.
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The basic study on activity of polyphenol oxidase (PPO) from different purple sweet potato (PSP) parts was mainly carried out here. The PPO activity and browning degree (BD) of PSP peel were higher than those of inner-tissue and intact sweet potatoes. The relativity between them was positive, and relativity coefficient was 0.9895. The activity of PPO extracted from sliced PSP increased initially and decreased afterwards, with the highest activity of PPO on the third day during storage. And BD increased very quickly as time went by, especially in the first three days. The relativity between PPO activity and BD was negative, and relativity coefficient was-0.8747.
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Zhang, Jianyou, Guangcheng Zhou, Lifeng Fei, Lifan Chen, Lei Sun, Fei Lyu, and Yuting Ding. "Study on Purification and Characterization of Polyphenol Oxidase from Acetes chinensis." Molecules 26, no. 24 (December 13, 2021): 7545. http://dx.doi.org/10.3390/molecules26247545.
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Acetes chinensis (belonging to the Decapoda Sergestidae genus) is widely distributed in East Asian waters and is extremely widespread and present in the shallow coastal areas of China. Polyphenol oxidase (PPO), which was extracted from Acetes chinensis, was purified in a four-step procedure involving phosphate-buffered saline treatment, ammonium sulphate precipitation, DEAE-Cellulose chromatography, and Phenyl-Sepharose HP chromatography, and then, its biochemical characterization was measured. The specific activity of the purified enzyme was increased to 643.4 U/mg, which is a 30.35 times increase in purification, and the recovery rate was 17.9%. L-dopa was used as the substrate, the enzymatic reactions catalyzed by PPO conformed to the Michaelis equation, the maximum reaction velocity was 769.23 U/mL, and the Michaelis constant Km was 0.846 mmol/L. The optimal pH of PPO from Acetes chinensis was 7.5, and the optimal temperature was 35 °C. The metal ions experiment showed that Mn2+ and K+ could enhance the activity of PPO; that Ba2+ and Ca2+ could inhibit the activity of PPO; and that Cu2+ had a double effect on PPO, increasing the PPO activity at low concentrations and inhibiting the PPO activity at high concentrations. The inhibitor experiment showed that the inhibitory effects of EDTA and kojic acid were weak and that ascorbic acid and sodium pyrophosphate had good inhibitory effects. The purification and characterization of Acetes chinensis serve as guidelines for the prediction of enzyme behavior, leading to effective prevention of enzymatic browning during processing.
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Jiang, Shu, and Michael H. Penner. "Role of Ascorbic Acid in the Extraction and Quantification of Potato Polyphenol Oxidase Activity." Foods 10, no. 10 (October 17, 2021): 2486. http://dx.doi.org/10.3390/foods10102486.
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The ability to accurately measure the activity of polyphenol oxidase (PPO) in complex matrices is essential. A problem encountered when using spectrophotometric methods is interference due to ascorbic acid (AA), often used as an enzyme “protecting agent” during PPO extraction. This study focuses on the nature of AA’s effect on spectrophotometric determinations of PPO activity as well as enzyme extraction. Potato extracts and semi-purified PPO were used as enzyme sources. The inactivation of PPO attributed to AA is substrate-mediated. The extent of AA-dependent inactivation of PPO in model systems varied between substrates. AA only slows mechanism-based inactivation of PPO induced by catechol, possibly owing to the prevention of quinone formation. AA minimally protects PPO activity during enzyme extraction. The problem associated with AA in PPO assay could be circumvented by using ascorbate oxidase to remove AA when catechol is the primary substrate or by using chlorogenic acid as the primary substrate.
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Padiglia, Alessandra, Paolo Zucca, Faustina B. Cannea, Andrea Diana, Cristina Maxia, Daniela Murtas, and Antonio Rescigno. "Absence of Polyphenol Oxidase in Cynomorium coccineum, a Widespread Holoparasitic Plant." Plants 9, no. 8 (July 30, 2020): 964. http://dx.doi.org/10.3390/plants9080964.
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Polyphenol oxidase (PPO, E.C. 1.14.18.1) is a nearly ubiquitous enzyme that is widely distributed among organisms. Despite its widespread distribution, the role of PPO in plants has not been thoroughly elucidated. In this study, we report for the absence of PPO in Cynomorium coccineum, a holoparasitic plant adapted to withstand unfavorable climatic conditions, growing in Mediterranean countries and amply used in traditional medicine. The lack of PPO has been demonstrated by the absence of enzymatic activity with various substrates, by the lack of immunohistochemical detection of the enzyme, and by the absence of the PPO gene and, consequently, its expression. The results obtained in our work allow us to exclude the presence of the PPO activity (both latent and mature forms of the enzyme), as well as of one or more genes coding for PPO in C. coccineum. Finally, we discuss the possible significance of PPO deficiency in parasitic plants adapted to abiotic stress.
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Hernández-Romero, Diana, Francisco Solano, and Antonio Sanchez-Amat. "Polyphenol Oxidase Activity Expression in Ralstonia solanacearum." Applied and Environmental Microbiology 71, no. 11 (November 2005): 6808–15. http://dx.doi.org/10.1128/aem.71.11.6808-6815.2005.
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ABSTRACT Sequencing of the genome of Ralstonia solanacearum revealed several genes that putatively code for polyphenol oxidases (PPOs). To study the actual expression of these genes, we looked for and detected all kinds of PPO activities, including laccase, cresolase, and catechol oxidase activities, in cellular extracts of this microorganism. The conditions for the PPO assays were optimized for the phenolic substrate, pH, and sodium dodecyl sulfate concentration used. It was demonstrated that three different PPOs are expressed. The genes coding for the enzymes were unambiguously correlated with the enzymatic activities detected by generation of null mutations in the genes by using insertional mutagenesis with a suicide plasmid and estimating the changes in the levels of enzymatic activities compared to the levels in the wild-type strain. The protein encoded by the RSp1530 locus is a multicopper protein with laccase activity. Two other genes, RSc0337 and RSc1501, code for nonblue copper proteins exhibiting homology to tyrosinases. The product of RSc0337 has strong tyrosine hydroxylase activity, and it has been shown that this enzyme is involved in melanin synthesis by R. solanacearum. The product of the RSc1501 gene is an enzyme that shows a clear preference for oxidation of o-diphenols. Preliminary characterization of the mutants obtained indicated that PPOs expressed by R. solanacearum may participate in resistance to phenolic compounds since the mutants exhibited higher sensitivity to l-tyrosine than the wild-type strain. These results suggest a possible role in the pathogenic process to avoid plant resistance mechanisms involving the participation of phenolic compounds.
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Gao, Lu, Li Chun Zhao, Ji Dong Duan, and Yan Li Tao. "Study on the Process of the Reaction Catalyzed by Polyphenol Oxidase from Purple Sweet Potato." Advanced Materials Research 898 (February 2014): 153–56. http://dx.doi.org/10.4028/www.scientific.net/amr.898.153.
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The polyphenol oxidase (PPO) was extracted from fresh purple sweet potato (PSP) by phosphate buffer solution, and spectrophotometry method was applied in the experiment. The process of the reaction catalyzed by PPO with different substrate concentrations and the relationship between enzyme concentrations and PPO activity were mainly studied here. The result showed that the effect of enzyme concentration on PPO activity was stronger than that of substrate concentration on PPO activity.
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Journal, Baghdad Science. "Extraction conditions of polyphenol oxidase from banana peel." Baghdad Science Journal 13, no. 3 (September 4, 2016): 469–74. http://dx.doi.org/10.21123/bsj.13.3.469-474.
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Polyphenol oxidase (PPO) is an enzyme containing copper, presents in various fruits and vegetables. It is responsible for the browning reactions when the cells are damaged during handling. The best conditions for extraction of polyphenol oxidase from banana peel was by using an extraction buffer containing phosphate buffer (0.05 M, pH 7), 0.01 M ascorbic acid and 0.5% polyethylene glycol, with extraction ratio 1:4 (w:v) for one minute by using blender. The enzyme activity was measured spectrophotometrically at 425 nm. PPO was studied to prevent the browning of banana peel which results in the loss of their marketability. The aim of this study was to determine the optimum conditions for polyphenol oxidase extraction from banana peel.
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Gundo[notdef]ggmaz, G., S. Do[notdef]ggan, and O. Arslan. "Some Kinetic Properties of Polyphenol Oxidase Obtained from Various Salvia Species (Salvia Viridis L., Salvia Virgata Jacq. and Salvia Tomentosa Miller)." Food Science and Technology International 9, no. 4 (August 2003): 309–15. http://dx.doi.org/10.1177/108201303036476.
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Polyphenol oxidase (PPO) was partially purified by (NH4)2SO4 precipitation followed by dialysis from different organs of Salvia species (Salvia virgata Jacq., Salvia viridis L. and Salvia tomentosa Miller). Polyphenol oxidase activity was measured spectrophotometrically at 420 nm using catechol as a substrate. Vmax, KM and Vmax/KM values for polyphenol oxidase activity from different organs of Salvia species were determined. S. tomentosa Miller was the species with the highest PPO activity, followed by S. virgata Jacq and S. viridis L. S. tomentosa Miller was the most suitable Salvia species for dark-tea preparations because of the highest Vmax/KM values. The effects of various inhibitors on the reaction catalysed by the enzyme were tested and calculated I50 values, reduced the enzyme activity by 50%. The most effective inhibitor was L-cysteine followed by ascorbic acid. Activation energies, Ea, were determined from Arrhenius equation.
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Robinson, SP, BR Loveys, and EK Chacko. "Polyphenol Oxidase Enzymes in the Sap and Skin of Mango Fruit." Functional Plant Biology 20, no. 1 (1993): 99. http://dx.doi.org/10.1071/pp9930099.
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Severe sapburn occurs in mango fruit of the cultivar Kensington when sap contacts the fruit, resulting in browning and then blackening of the skin. Both the sap and skin of mango fruit contained considerable polyphenol oxidase (PPO) activity. The sap enzyme was not activated by SDS, was inhibited by hexadecyltrimethylammonium bromide, and was active with both para- and ortho-diphenol substrates. The skin enzyme was activated by SDS, was inhibited by salicylhydroxamic acid and polyvinylpyrrolidone, and was active only with ortho-diphenol substrates. These properties suggest that the sap PPO is a laccase-type enzyme (EC 1.10.3.2) whereas the skin contains the more common catechol oxidase-type PPO (EC 1.10.3.1). The skin enzyme had a temperature optimum at 30�C but the sap enzyme had maximum PPO activity at 75�C. Both enzymes were relatively thermostable, requiring more than 15 min at 80�C for 50% loss of activity. It is concluded that browning of mango skin induced by the sap is predominantly catalysed by PPO in the skin and that this is unlikely to be prevented by heat treatment of the fruit.
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Gao, Lu, Lin Lin, Li Chun Zhao, and Fan Wu. "Study on Heat Stability of Polyphenol Oxidase from Purple Sweet Potato." Applied Mechanics and Materials 716-717 (December 2014): 122–25. http://dx.doi.org/10.4028/www.scientific.net/amm.716-717.122.
Full textAbstract:
The basic study on heat stability of polyphenol oxidase (PPO) from purple sweet potato (PSP) was mainly carried out here. Research on thermal stability showed that PPO from PSP was very sensitive to the changes of temperatures. The optimum temperature of PPO was 16°C with the second optimum temperature of 30°C and PPO activity dropped rapidly when temperature was below 5°C or above 45°C. Half-lives of PPO were 450, 240, 66, 50, 21 and 13s respectively at tested temperatures from 65 to 90 °C at 5°C intervals.
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Saeidian, Shahriar. "Kinetics Properties of Polyphenol Oxidase in Hawthorn (Crataegus spp)." International Letters of Natural Sciences 25 (September 2014): 29–38. http://dx.doi.org/10.18052/www.scipress.com/ilns.25.29.
Full textAbstract:
Polyphenol oxidase (PPO) from hawthorn was extracted and partially purified through (NH4)2SO4 precipitation, dialysis and ion exchange chromatography. The activity of polyphenol oxidase was investigated in Crataegus spp. Spectrophotometric method was used to assay the enzyme activity and the kinetic constants - maximum enzyme velocity (Vmax) and Michealis - Menten constant (Km). Of the substrates tested, catechol was the best substrate for PPO with a Km value of 2.2 mM. The optimum pH for PPO activity was found to be 7. The enzyme showed high activity over a broad pH range of 4 - 8. The optimal pH and temperature for enzyme activity were found to be 7 and 40-45 °C, respectively. km value for hawthorn PPO is calculated 22 mM for catechol and 6.7 mM for pyrogallol and 9.7 mM for L-dopa. As can be seen, affinity of PPOs for various substrates varies widely. The enzyme showed a broad activity over a broad pH and temperature range. The thermal inactivation studies showed that the enzyme is heat resistant. The enzyme showed the highest activity toward pyrogallol and no activity toward tyrosine. Of the inhibitors tested, the most potent inhibitors were kojic acid, cysteine and glycine , respectively
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Underhill, SJR, and C. Critchley. "Cellular Localisation of Polyphenol Oxidase and Peroxidase Activity in Litchi chinensis Sonn. Pericarp." Functional Plant Biology 22, no. 4 (1995): 627. http://dx.doi.org/10.1071/pp9950627.
Full textAbstract:
Cellular localisation of visual browning and oxidative activity studies were conducted to determine the relative significance of polyphenol oxidase (PPO) and peroxidase (POD) activities during pericarp browning. Pericarp browning was first observed on the protuberance apices and subsequently extended uniformly over the entire pericarp surface. Anatomically, browning was highly localised and restricted to the epicarp and the upper mesocarp. PPO and POD activities were highest in the epicarp, with progressively less activity in both the mesocarp and endocarp. In situ localisation of oxidative activity using tissue blots confirmed high epicarp PPO activity. POD activity, although primarily restricted to mesocarp vascular tissue, was also detected in the epicarp. We believe that litchi pericarp browning is due to highly localised oxidative activity in the epicarp and upper mesocarp. As PPO and POD activities were significantly higher in this tissue and browning was not observed when both enzymes were selectively inhibited, it is postulated that both PPO and POD activities are associated with litchi pericarp browning. The current theory that litchi pericarp browning is only caused by PPO activity needs to be re-appraised to determine the relative role of POD activity.
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Sanni, David Morakinyo, Catherine Joke Adeseko, and Samuel Olufemi Bamidele. "Purification and biochemical characterization of polyphenol oxidase from seeds of melon (Citrullus colocynthis)." Nova Biotechnologica et Chimica 19, no. 2 (December 1, 2020): 223–31. http://dx.doi.org/10.36547/nbc.v19i2.777.
Full textAbstract:
Polyphenol oxidase (PPO) is an enzyme that is responsible for the enzymatic browning of fruits and vegetables. This is generally undesired process and need to be prevented in food technology. PPO from seeds of Citrullus colocynthis was purified, the physicochemical properties such as effects of pH and temperature, substrate specificity, effects of inhibitors and cations on PPO activity and the kinetic parameters for four substrates namely, catechol, L-DOPA, gallic acid and tyrosine, were determined. The purification steps resulted in 41-fold with 10 % yield, and the optima pH and temperature values for PPO from C. colocynthis were found to be pH 7.0 and 60 °C, respectively using catechol as substrate. About 9 % enzyme initial activity was retained after 60 min of incubation at 80 °C, and the apparent molecular weight was determined as 42 kDa by partially denaturing SDS-PAGE. PPO activity was inhibited by ascorbic acid, SDS and certain divalent (Ca2+, Zn2+, Mg2+ and, Fe2+) and monovalent (Na+) metal. Moreover, purified enzyme solution showed diphenolase activity toward catechol, gallic acid, L-DOPA and monophenolase activity toward tyrosine, therefore, tyrosinase was identified as the only one PPO in C. colocynthis seeds. This study revealed the use of temperature above 80 °C to inhibit PPO activity during processing and storage of melon seeds.
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Sanni, D. M., T. H. Fatoki, and O. V. Omotoyinbo. "Comparative Evaluation of Computational and Experimental Analysis of Polyphenol Oxidase from Cocoa (Theobroma cacao L.)." Journal of Microbiology and Biotechnology Research 7, no. 1 (March 29, 2017): 18. http://dx.doi.org/10.24896/jmbr.2017714.
Full textAbstract:
Cocoa (Theobroma cacao L.) is a cash crop of huge economic significance in the world and the key raw material for chocolate manufacturing. Polyphenol oxidases (PPOs) are copper containing oxidoreductases that catalyze the hydroxylation and oxidation of phenolic compounds in the presence of molecular oxygen. The PPO presence and activity during fermentation and drying of cocoa beans is responsible for the development of flavor precursors. In this study, bioinformatics analysisof PPO from cocoa was done using standard bioinformatics tools such as Blastp, Hmmer, ClustalO, OMABrowser, EMBOSS and Swissmodel. The result showed that cocoa PPO homologs include Citrus sinensis, Populus euphratica, Gossypium raimondii, Litchi chinensis, Dimocarpuslongan, Canarium album, while the orthologsobtainedinclude Sorghum bicolor, Zea may, Manihot esculenta and Vitis vinifera among others.PPO of Solanum lycopersicum (tomato) was found to be a distant homolog of cocoa PPO, and that this evolutionary relationship implicated Witches’ Broom Disease (WBD). The computed physicochemical properties were in alignment with the experimental results. Keywords: Polyphenol Oxidase, Cocoa, Theobroma cacao L., Computational Analysis, Experimental Analysis.
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Brannan, Robert G. "Polyphenol Oxidase in Pawpaw (Asimina triloba [L.] Dunal) Fruit Pulp from Different Varieties." Journal of Food Research 5, no. 1 (December 22, 2015): 33. http://dx.doi.org/10.5539/jfr.v5n1p33.
Full textAbstract:
Pawpaw (<em>Asimina triloba</em> L. Dunal) is a tree fruit from the tropical Annonaceae family. Pawpaw currently has very limited commercial production because of its high perishability. Polyphenol oxidase (PPO) is responsible for enzymatic browning in pawpaw pulp. The objective of this research is to characterize PPO extracted from different pawpaw varieties. With respect to PPO activity, six of the varieties (Taytwo, Rebecca’s Gold, NC-1, Overleese, Rappahannock, and Green River Belle) exhibited PPO activity that was statistically higher than Quaker’s Delight and Lynn’s Favorite. The other four varieties (SAA Zimmerman, Shenendoah, KSU-Atwood, IXL) exhibited PPO activity that was not significantly different from each other or Quaker’s Delight and Lynn’s Favorite, but were significantly lower than Taytwo, Rebecca’s Gold, and NC-1. Kinetic parameters (Vmax, Km) and their ratio can be used to relate enzyme velocity with substrate affinity. Varieties that exhibited a high ratio, i.e. a very active enzyme due to a high Vmax and/or a low Km, are Rebecca’s Gold, Taytwo, NC-1, and KSU-Atwood). The results presented indicate that certain varieties exhibit conditions that suggest PPO could have a lower inherent impact on tissue browning, especially Lynn’s Favorite, Green River Belle, IXL, SAA Zimmerman, and Overleese. On the other hand, certain varieties (Taytwo, Rebecca’s Gold, NC-1, and perhaps KSU Atwood) exhibit PPO activity, Vmax, and Km values that suggest inherently high PPO activity and thus increased potential for browning. Overall, understanding PPO activity may help to explain post-harvest discoloration of pawpaw pulp and aid the commercial selection of more shelf-stable varieties.
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Weerawardana, Michelle B. S., Gobika Thiripuranathar, and Priyani A. Paranagama. "Natural Antibrowning Agents against Polyphenol Oxidase Activity in Annona muricata and Musa acuminata." Journal of Chemistry 2020 (April 14, 2020): 1–6. http://dx.doi.org/10.1155/2020/1904798.
Full textAbstract:
Fresh-cut fruits and vegetables emerge as popular food for consumers in retail markets. However, a loss of millions of dollars yearly to the food industry has been due to discoloration of fruits and vegetables caused by a pronounced reaction called enzymatic browning, which is caused by the activity of the polyphenol oxidase enzyme present in most of the fruits and vegetables. The main objective of this study was to investigate the natural antibrowning effects of the aqueous extract of ginger and essential oil of cinnamon bark on PPO enzymatic activity in Annona muricata (katu anoda) and Musa acuminata (ash plantains), which are considered to be widely consumable by Sri Lankans due to its respective health benefits. The antibrowning activity analyzed using a UV-visible spectrophotometer at a wavelength of 525 nm showed that cinnamon bark oil of 0.0035 g/mL had a % inhibitory activity of 51.97 percent on PPO activity in Annona muricata and 49.51 percent on PPO activity in Musa acuminata, while the aqueous extract of ginger of 0.091 g/mL had a % inhibitory activity of 60.90 percent on PPO activity in Annona muricata and 48.10 percent on PPO activity in Musa acuminata, respectively. This study shows that cinnamon bark oil and ginger can be used as effective, natural, nontoxic antibrowning agents that can inhibit the activity of the PPO enzyme, thereby preventing the essence and nutritional benefits of fruits and vegetables.
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Prasad, Abhishek, and Tirthartha Chattopadhyay. "Molecular marker assisted screening for kernel polyphenol oxidase activity in wheat Triticum aestivum L." Journal of Applied and Natural Science 13, no. 1 (January 31, 2021): 8–15. http://dx.doi.org/10.31018/jans.v13i1.2445.
Full textAbstract:
High level of kernel polyphenol oxidase (PPO) activity has been found to be the major factor behind time-dependent discolouration of wheat-based products, which ultimately leads to reduced consumers’ preference. Till date, 6 genes belonging in 2 paralogous sets present in wheat (Triticum aestivum L.) chromosome 2 homeologues (2A, 2B and 2D) have been reported to govern kernel PPO activity. Among these 6 genes, perfect molecular markers have been developed for 2 genes (PPOA1 and PPOD1) and the major role of PPOA1 gene in governing kernel PPO activity in wheat has been reported. In the present study we have used the molecular markers for the PPOA1 and PPOD1 genes to characterize wheat genotypes for their kernel PPO activity. We have successfully converted the dominant marker assay for the PPOD1 locus into a co-dominant assay using the already reported primers. Our molecular screening strategy could explain the kernel PPO activity of wheat genotypes in rapid, reliable and environment-independent manner. Furthermore, biochemical estimation of kernel PPO activity in wheat genotypes indicated the involvement of other genes in fine-tuning this important trait. Thus, the present study should facilitate the breeders in marker-assisted selection and breeding for developing wheat genotypes with low kernel PPO activity.
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Saeidian, Shahriar. "Kinetics Properties of Polyphenol Oxidase in Hawthorn (<i>Crataegus spp</i>)." International Letters of Natural Sciences 25 (September 2, 2014): 29–38. http://dx.doi.org/10.56431/p-64t842.
Full textAbstract:
Polyphenol oxidase (PPO) from hawthorn was extracted and partially purified through (NH4)2SO4 precipitation, dialysis and ion exchange chromatography. The activity of polyphenol oxidase was investigated in Crataegus spp. Spectrophotometric method was used to assay the enzyme activity and the kinetic constants - maximum enzyme velocity (Vmax) and Michealis - Menten constant (Km). Of the substrates tested, catechol was the best substrate for PPO with a Km value of 2.2 mM. The optimum pH for PPO activity was found to be 7. The enzyme showed high activity over a broad pH range of 4 - 8. The optimal pH and temperature for enzyme activity were found to be 7 and 40-45 °C, respectively. km value for hawthorn PPO is calculated 22 mM for catechol and 6.7 mM for pyrogallol and 9.7 mM for L-dopa. As can be seen, affinity of PPOs for various substrates varies widely. The enzyme showed a broad activity over a broad pH and temperature range. The thermal inactivation studies showed that the enzyme is heat resistant. The enzyme showed the highest activity toward pyrogallol and no activity toward tyrosine. Of the inhibitors tested, the most potent inhibitors were kojic acid, cysteine and glycine , respectively
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Doğan, S., Y. Ayyildiz, M. Doğan, ü. Alan, and M. E. Diken. "Characterisation of polyphenol oxidase from Melissa officinalis L. subsp. officinalis (lemon balm)." Czech Journal of Food Sciences 31, No. 2 (April 18, 2013): 156–65. http://dx.doi.org/10.17221/288/2011-cjfs.
Full textAbstract:
Polyphenol oxidase (PPO) from Melissa officinalis L. subsp. officinalis (lemon balm) was partially purified by ammonium sulphate precipitation and dialysis; and then it was characterised in detail in terms of pH and temperature optima, thermal stability, kinetic parameters, and inhibition properties. Based on experimental results, it was found out that (i) the optimum pH and temperature values of PPO were 6.5, 4.0, and 8.5 and 40, 50, and 60°C for catechol, 4-methylcatechol and pyrogallol substrates, respectively; (ii) the best substrate was pyrogallol due to the highest V<sub>max</sub>/K<sub>m</sub> value, followed by catechol and 4-methylcatechol; (iii) enzyme activity decreased due to heat denaturation of the enzyme with increasing temperature and inactivation time for all substrates; (vi) gallic acid and l-glutamic acid did not inhibit PPO; and (v) the most effective inhibitor was glutathione. Furthermore, the phenolic and protein contents of lemon balm extract were also determined according to the Folin-Ciocalteu and Bradford methods, respectively.
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Hojnik Podrepšek, Gordana, Željko Knez, and Maja Leitgeb. "The Influence of Supercritical Carbon Dioxide on Graham Flour Enzyme Polyphenol Oxidase Activity." Molecules 25, no. 24 (December 17, 2020): 5981. http://dx.doi.org/10.3390/molecules25245981.
Full textAbstract:
Graham flour is a form of whole wheat flour made by grinding the endosperm and is thus also the most nutritious. Generally, the enzyme polyphenol oxidase (PPO) catalyzes two different reactions in the presence of molecular oxygen: the hydroxylation of monophenols to ortho-diphenol and the oxidation of o-diphenol to o-quinone. The purpose of the work was to inactivate PPO activity to extend the shelf life of graham flour and at the same time preserve all the of its high-quality properties. The influence of supercritical CO2 (scCO2) treatment on PPO activity in graham flour was investigated. First, graham flour was exposed to scCO2 conditions, then the proteins were extracted, and in the last step the concentration of total proteins and the specific activity of the PPO enzyme were determined by spectrophotometric assay. PPO activity decreased with an increase in treatment pressure. Furthermore, the flour quality characteristics that meet all needs for wheat end-use products after scCO2 treatment have been preserved. No major changes in the structure of the granulate or shape of the flour particles were observed. A slightly reduced value of the moisture content in scCO2-treated graham flour also implies an extension of the shelf life.
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Murniati, Anceu, Buchari Buchari, Suryo Gandasasmita, Zeily Nurachman, Arie Hardian, and Dera Triani. "Immobilization of Crude Polyphenol Oxidase Extracts from Apples on Polypyrrole as a Membrane for Phenol Removal." Jurnal Kimia Sains dan Aplikasi 24, no. 2 (March 8, 2021): 62–69. http://dx.doi.org/10.14710/jksa.24.2.62-69.
Full textAbstract:
This research aims to make a polypyrrole (PPy) membrane and crude extract of polyphenol oxidase (PPO) as a membrane of mPPy/PPO apple extracts. The membrane of PPy/PPO-apple extract has been synthesized by the electrodeposition method. The electrolyte composition consists of a mixture of 0.10-0.20 M pyrrole (Py) and 50-100% PPO apple extract, which is stable using 50 mM of phosphate buffer solution at pH 6.80-7.00 and room temperature. The electrodeposition process is used 400 mesh steel gauze anode ST-304 and carbon plate cathode. Electrodeposition is carried out at potential = 5.00-6.00 V; current = 0.02-0.25 A; the distance from both electrodes = 1.00-2.00 cm for 300-500 seconds. The results from the deposition of PPy/PPO apple extract of the anode are a membrane of mPPy/PPO-apple extract, with total enzyme activity (U) = (957,1441, 2287 and 1754) using 2.00-5.00 mM phenol as a substrate which is measured based on the UV-visible spectrophotometric method. PPy and mPPy/PPO-apple extracts were characterized by SEM and SEM-EDS. The membrane of mPPy/PPO-apple extract can be used to remove phenol in industrial wastewater samples is 50-65% with a filtration capacity of 500 mL for 2 hours.
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Wojdyło, Aneta, Jan Oszmiański, and Paweł Bielicki. "Polyphenolic Composition, Antioxidant Activity, and Polyphenol Oxidase (PPO) Activity of Quince (Cydonia oblonga Miller) Varieties." Journal of Agricultural and Food Chemistry 61, no. 11 (March 6, 2013): 2762–72. http://dx.doi.org/10.1021/jf304969b.
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Sarsenova, Assemgul, Dudu Demir, Kardelen Çağlayan, Sardarbek Abiyev, Talshen Darbayeva, and Cafer Eken. "Purification and Properties of Polyphenol Oxidase of Dried Volvariella bombycina." Biology 12, no. 1 (December 28, 2022): 53. http://dx.doi.org/10.3390/biology12010053.
Full textAbstract:
Polyphenol oxidase (PPO) was purified and characterized from a dried wild edible and medicinal mushroom (Volvariella bombycina). Using Sepharose 4B-L-tyrosine-p-aminobenzoic acid affinity chromatography, PPO was purified from the dried V. bombycina. The purification was completed with a 33.85-fold purification. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), the purified enzyme migrated as a single band. The molecular weight of the purified enzyme was estimated by SDS-PAGE to be about 25 kDa. Catechol, 4-methyl catechol, and pyrogallol were used as substrates to determine the enzyme activity and its kinetic parameters (Km and Vmax). At the optimum pH and temperature, dried V. bombycina PPO’s Km and Vmax values for catechol, 4-methyl catechol, and pyrogallol were found to be 1.67 mM–833.33 U/mL, 3.17 mM–158.73 U/mL, and 2.67 mM–3333.33 U/mL, respectively. Also investigated were the effects of pH and temperature on the enzymatic properties of PPO in dried V. bombycina. The optimum pH and temperature values for dried V. bombycina PPO obtained by using catechol, 4-methyl catechol, and pyrogallol as substrates were 6.5, 15 ℃; 9.0, 20 ℃; and 8.0, 15℃, respectively. This is the first study on the purification and characterization of PPO from dried V. bombycina.
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McConchie, Robyn, N. Suzanne Lang, Alan R. Lax, and Gregory A. Lang. "Reexamining Polyphenol Oxidase, Peroxidase, and Leaf-blackening Activity in Protea." Journal of the American Society for Horticultural Science 119, no. 6 (November 1994): 1248–54. http://dx.doi.org/10.21273/jashs.119.6.1248.
Full textAbstract:
Premature leaf blackening in Protea severely reduces vase life and market value. The current hypothesis suggests that leaf blackening is induced by a sequence of events related to metabolic reactions associated with senescence, beginning with total depletion of leaf carbohydrates. It is thought that this carbohydrate depletion may induce hydrolysis of intercellular membranes to supply respiratory substrate, and subsequently allow vacuole-sequestered phenols to be oxidized by polyphenol oxidase (PPO) and peroxidase (POD) (Whitehead and de Swardt, 1982). To more thoroughly examine this hypothesis, leaf carbohydrate depletion and the activities of PPO and POD in cut flower Protea susannae × P. compacta stems held under light and dark conditions were examined in relationship to postharvest leaf blackening. Leaf blackening proceeded rapidly on dark-held stems, approaching 100% by day 8, and was temporally coincident with a rapid decline in starch concentration. Blackening of leaves on light-held stems did not occur until after day 7, and a higher concentration of starch was maintained earlier in the postharvest period for stems held in light than those held in dark. A large concentration of the sugar alcohol, polygalatol, was maintained in dark- and light-held stems over the postharvest period, suggesting that it is not involved in growth or maintenance metabolism. Polyphenol oxidase activity in light- and dark-held stems was not related to appearance of blackening symptoms. Activity of PPO at pH 7.2 in light-held stems resulted in a 10-fold increase over the 8-day period. Activity in dark-held stems increased initially, but declined at the onset of leaf blackening. There was no significant difference in POD activity for dark- or light-held stems during the postharvest period. Total chlorophyll and protein concentrations did not decline over the 8-day period or differ between light- and dark-held stems. Total phenolics in the dark-held stems increased to concentrations ≈30% higher than light-held stems. Consequently, the lack of association between membrane collapse, leaf senescence, or activities of oxidative enzymes (PPO or POD) with leaf blackening does not support the hypothesis currently accepted by many Protea researchers. An alternative scenario may be that the rapid rate of leaf starch hydrolysis imposes an osmotic stress resulting in cleavage of glycosylated phenolic compounds to release glucose for carbohydrate metabolism and coincidentally increase the pool of free phenolics available for nonenzymatic oxidation. The physiology of such a carbohydrate-related cellular stress and its manifestation in cellular blackening remains to be elucidated.
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Ke, Dangyang, and Mikal E. Saltveit. "Regulation of Russet Spotting, Phenolic Metabolism, and IAA Oxidase by Low Oxygen in Iceberg Lettuce." Journal of the American Society for Horticultural Science 114, no. 4 (July 1989): 638–42. http://dx.doi.org/10.21273/jashs.114.4.638.
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Abstract A 1.5% O2 atmosphere, relative to normal air, dramatically inhibited ethylene-induced russet spot development, PAL, and ionically bound POD, and ionicaliy bound IAA oxidase activities and reduced soluble phenolic content in stored iceberg lettuce (Lactuca sativa L.). Low O2 also inhibited eythylene production and respiration. Polyphenol oxidase activity was slightly inhibited by low O2. The results suggest that low O2 inhibition of ethylene action and attendant effects on phenolic metabolism and IAA oxidase activity may be responsible for inhibition of russet spotting by 1.5% O2. Chemical names used: indole-3-acetic acid (IAA); phenylalanine ammonia-lyase (PAL); peroxidase (POD); polyphenol oxidase (PPO).
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Ebrahimi, Peyman, Carlo Nicoletto, Paolo Sambo, Federica Tinello, Dasha Mihaylova, and Anna Lante. "Impact of Agronomic Treatments on the Enzymatic Browning of Eggplants (Solanum melongena L.)." Antioxidants 12, no. 2 (February 8, 2023): 410. http://dx.doi.org/10.3390/antiox12020410.
Full textAbstract:
Enzymatic browning could negatively affect the sensory and nutritional properties of eggplants post-harvest. Polyphenols, polyphenol oxidase (PPO), and reactive oxygen species (ROS) are three material conditions involved in enzymatic browning. This paper seeks to evaluate the effect of fertilization techniques and grafting on the activity of PPO and colorimetric parameters in cultivated eggplants. Fertilization alone significantly increased the PPO activity in all eggplant fleshes (p ≤ 0.05), whereas the grafting technique combined with fertilization decreased the PPO activity in most of the samples significantly (p ≤ 0.05). Moreover, there was a significant positive correlation between the PPO activity and the a* values of the eggplants. The a* values in grafted eggplants were significantly different from each other (p ≤ 0.05), showing that grafting the fertilized eggplants could be effective in controlling the enzymatic browning. The eggplant slices exposed to air for 60 min at room temperature showed a significant increase (p ≤ 0.05) in PPO activity, browning index (BI), total color difference (ΔE), and a*, b*, and c* values. Thus, it is necessary to minimize the exposure time of the slices to air at room temperature, even if combining fertilization techniques with grafting could delay the enzymatic browning in fresh-cut eggplants.
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Ma, Yuan, Ming Luo, Yingping Xu, Yingjia Liu, Xiaocui Liu, Xiufang Bi, Yiping Yuan, Fan Su, and Xiaocui Yin. "Purification and characterization of a thaumatin-like protein-1 with polyphenol oxidase activity found in Prunus mume." RSC Advances 10, no. 48 (2020): 28746–54. http://dx.doi.org/10.1039/d0ra05659f.
Full textAbstract:
Thaumatin-like protein-1 (TLP-1), a protein displaying high polyphenol oxidase (PPO) action and a member of the pathogenesis-related (PR) protein family, has a considerable influence on the enzymatic browning of Prunus mume (Chinese plum).
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Vallejo, Roger L., Wanda W. Collins, and Robert H. Moll. "Inheritance of A and B Glandular Trichome Density and Polyphenol Oxidase Activity in Diploid Potatoes." Journal of the American Society for Horticultural Science 119, no. 4 (July 1994): 829–32. http://dx.doi.org/10.21273/jashs.119.4.829.
Full textAbstract:
Glandular trichomes from some Solanum species have suppressed infestation by insects including green peach aphid, which is a main vector of potato virus Y (PVY) and potato leaf roll virus (PLRV), both of which contribute to a serious loss in potato production. Eight Solanum phureja Juz. et Buk.-S. stenotomum Juz. (Phu-Stn), three S. berthaultii Hawkes (Ber), nine F1 [(Phu-Stn) × Ber], fifteen backcross (BC) [(Phu-Stn) × F1], and seventeen reciprocal BC (BCR) [F1 × (Phu-Stn)] families were evaluated to determine the genetic variability and heritability of A and B glandular trichome density and polyphenol oxidase (PPO) activity. Experiments were carried out in completely randomized and randomized complete-block designs in the greenhouse. Genetic analysis was done using half-sib family and parent-offspring regression analysis. Phu-Stn showed a higher density of A trichomes than Ber and F1, while the BC and BCR had densities of A trichomes similar to Phu-Stn. B trichomes were not observed in Phu-Stn. Ber showed a high B trichome density, which was transmitted to the F1. In the BC, B trichomes were almost absent, but, in the BCR, the density of B trichomes was higher than that of BC. Ber and F1 had similar or higher PPO activity than Phu-Stn. PPO activity decreased in the BC, but, in the BCR, it was high and similar to Ber and F1. Broad-sense heritability estimates for A and B trichome density and PPO activity were from medium to high (0.48 to 0.77) in Phu-Stn, Ber, and F1. Narrow-sense heritability estimates for A and B trichome density and PPO activity were very low (0.04 to 0.24) in BC and BCR. In the BC families, additive genetic variance was very low for A and B trichome density and PPO activity. Half-sib family selection based on progeny testing and combined with BCs to Phu-Stn in subsequent generations would be a suggested breeding procedure to improve these traits. Phenotypic correlations between A and B trichome densities were 0.26 (F1) and 0.44 (BCR), between A trichome density and PPO activity 0.20 (F1) and 0.31 (BCR), and between B trichome density and PPO activity 0.04 (F1) and 0.27(BCR. Positive associations found between traits might facilitate simultaneous improvement for high levels of A and B trichome density and PPO activity.
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Zhu, Lijuan, Linhu Zhu, Ayesha Murtaza, Yan Liu, Siyu Liu, Junjie Li, Aamir Iqbal, Xiaoyun Xu, Siyi Pan, and Wanfeng Hu. "Ultrasonic Processing Induced Activity and Structural Changes of Polyphenol Oxidase in Orange (Citrus sinensis Osbeck)." Molecules 24, no. 10 (May 18, 2019): 1922. http://dx.doi.org/10.3390/molecules24101922.
Full textAbstract:
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.
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Milani*, Jafar. "Susceptibility of Five Apple Cultivars to Browning." HortScience 39, no. 4 (July 2004): 780C—780. http://dx.doi.org/10.21273/hortsci.39.4.780c.
Full textAbstract:
Phenolic compounds and polyphenol oxidase (ppo) activity in five apple cultivars were assessed in relation tobrowning susceptibility. The degree of browning was determined by measuring brown pigments in homogenised pulp. The analysis variance of the browning rate, polyphenol content and ppo activity showed that only the effect of cultivar was significant while the interaction of location and cultivar not significant. Comparison of means (Duncan) classified the cultivars in view of browning rate in three groups (P < 0.01): Strong (Red Delicious), weak (Arangeh and Granny Smith), and mid (Golden Delicious). Arangeh was the superior variety due to its highest total soluble solids and lowest browning rate.
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Azzouzi, Naima, Mohammed Reda Britel, and Amal Maurady. "Characterization of Polyphenol Oxidase (PPO) from Blackberry Thorny Wild Rubus Fruticosus and its Inhibition using Natural Extracts." Current Research in Nutrition and Food Science Journal 10, no. 3 (December 20, 2022): 1205–21. http://dx.doi.org/10.12944/crnfsj.10.3.33.
Full textAbstract:
The Polyphenol oxidase (PPO) leads to the enzymatic browning of fruits and vegetables and needs to be prevented in food browning and quality. The present study aimed to investigate the use of natural extracts and chemical inhibitors to prevent browning of the PPO of blackberries. Purification, characterization, and kinetics of PPO of blackberry parameters for five substrates, namely, pyrocatechol, 4-methylcatechol, Pyrogallol, Gallic acid, and tyrosine, were described. The results showed that the DEAE-Sepharose and Superdex G-200 purification methods, which achieved electrophoretic purity, increased PPO activity by 556 fold. Purification with Sephadex GE-200 and SDS-PAGE reveals two PPO isoenzymes with an apparent molecular weight of 22 kD and 70 kD. The optimum pH and temperature values indicated were 6.6 and 25°C, respectively. The PPO showed variable affinity towards o-dihydroxy phenolic substrates with catecholase activity but without any activity observed with phenol, a monohydroxy substrate, and it was very effective towards pyrocatechol, pyrogallol, and 4-methyl catechol. The results revealed that inhibition of the PPO using both synthetic inhibitors and natural extracts was the most effective method. Quercetin and ascorbic acid showed higher inhibition with the lowest Ki values. Fresh onion (Allium cepa) and wild Arbutus unedo extract were able to inhibit the blackberry PPO activity up to 50% and 60%, respectively. Therefore, the use of natural extracts from Arbutus unedo L as anti-browning agents on the blackberry PPO may provide new insight to overcome the enzymatic browning.
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CHEN, L., B. H. INGHAM, and S. C. INGHAM. "Polyphenol Oxidase Activity as a Potential Intrinsic Index of Adequate Thermal Pasteurization of Apple Cider." Journal of Food Protection 67, no. 5 (May 1, 2004): 908–14. http://dx.doi.org/10.4315/0362-028x-67.5.908.
Full textAbstract:
In response to increasing concerns about microbial safety of apple cider, the U.S. Food and Drug Administration has mandated treatment of cider sufficient for a 5-log reduction of the target pathogen. Pasteurization has been suggested as the treatment most likely to achieve a 5-log reduction, with Escherichia coli O157:H7 as the target pathogen. Regulators and processors need a reliable method for verifying pasteurization, and apple cider polyphenol oxidase (PPO) activity was studied as a potential intrinsic index for thermal pasteurization. The effect of pasteurization conditions and apple cider properties on PPO activity and survival of three pathogens ( E. coli O157:H7, Salmonella, and Listeria monocytogenes) was studied using a Box-Behnken response surface design. Factors considered in the design were pasteurization conditions, i.e., hold temperature (60, 68, and 76° C), preheat time (10, 20, 30 s), and hold time (0, 15, 30 s), pH, and sugar content (° Brix) of apple cider. Response surface contour plots were constructed to illustrate the effect of these factors on PPO activity and pathogen survival. Reduction in PPO activity of at least 50% was equivalent to a 5-log reduction in E. coli O157:H7 or L. monocytogenes for cider at pH 3.7 and 12.5 ° Brix. Further studies, however, are needed to verify the relationship between PPO activity and pathogen reduction in cider with various pH and ° Brix values.
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Zhong, Lian, Jin Li, Dawei Tian, Jun Cai, Han Wang, and Qimin Ma. "Immobilization of polyphenol oxidase on chitosan/organic rectorite composites for phenolic compounds removal." Water Science and Technology 83, no. 4 (January 21, 2021): 906–21. http://dx.doi.org/10.2166/wst.2021.024.
Full textAbstract:
Abstract Chitosan/organic rectorite (CTS/OREC) composites were prepared and characterized by Fourier transform infrared spectrometry and X-ray diffraction. Polyphenol oxidase (PPO) was immobilized on CTS/OREC by physical adsorption (APPO) and covalent binding (CPPO). Taguchi method was applied in the optimization of immobilization conditions resulting in the highest enzyme activity of 16.37 × 103 and 8.92 × 103U/g for APPO and CPPO, respectively. APPO enzyme activity was higher than that of CPPO, while CPPO showed the higher enzyme loading capacity than that of APPO. The removal percentage of phenolic compound, including phenol (PH), 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP), by immobilized PPO was also explored. The results indicated that APPO was more efficient in phenolic compounds removal than CPPO. APPO contributed to a quick removal in the first hour, and the removal percentage of PH, 4-CP and 2,4-DCP could reach 69.3 ± 4.2%, 89.8 ± 2.5% and 93.8 ± 1.7% within 2 h, respectively. The order of removal percentage of phenolic compounds for both immobilized PPO was 2,4-DCP > 4-CP > PH. After 10 consecutive operations, the removal percentage of 2,4-DCP reached 73.2 ± 2.6% and 60.3 ± 1.5% for APPO and CPPO, respectively. The results introduced a novel support for PPO immobilization, and the immobilized PPO had great potential in wastewater treatment.
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Lee, M. R. F., F. R. Minchin, R. D. Hatfield, and M. L. Sullivan. "Red clover polyphenol oxidase reduces ruminal lipolysis in in vitro batch culture." Proceedings of the British Society of Animal Science 2007 (April 2007): 25. http://dx.doi.org/10.1017/s1752756200019281.
Full textAbstract:
It has been shown that the rate of lipolysis and proteolysis differs significantly between red clover genotypes with different levels of polyphenol oxidase (PPO) activity (Lee et al. 2004). Sullivan and Hatfield, (2006) reported the development of genetically modified isolines of red clover with the PPO1 gene silenced. This material was used to examine the role of the red clover PPO enzyme on lipolysis and ultimately C18 polyunsaturated fatty acid biohydrogenation in batch culture. If the role of PPO in reducing ruminal lipolysis of plant lipids is proven it would influence breeding strategies for forages which exhibit this trait in an attempt to increase the levels of beneficial PUFA and decrease detrimental trans and saturated fatty acids in animal products.
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Raj, S. Niranjan, B. R. Sarosh, and H. S. Shetty. "Induction and accumulation of polyphenol oxidase activities as implicated in development of resistance against pearl millet downy mildew disease." Functional Plant Biology 33, no. 6 (2006): 563. http://dx.doi.org/10.1071/fp06003.
Full textAbstract:
Polyphenol oxidase (PPO) activity was analysed in seedlings of resistant and susceptible pearl millet [Pennisetum glaucum (L.) R.Br] cultivars with or without inoculation of the downy mildew pathogen Sclerospora graminicola (Sacc.) Schroet. Seedlings of resistant varieties had greater PPO activity than susceptible seedlings, and inoculated seedlings had significantly higher PPO levels than uninoculated seedlings. Temporal accumulation of PPO showed a maximum activity at 24 h post-inoculation in resistant seedlings, whereas in susceptible seedlings it peaked at 48 h. PPO activity was positively correlated with levels of downy mildew resistance in different pearl millet cultivars under field conditions. Native PAGE staining showed four isoforms of PPO, which were differentially induced in relation to the time of appearance and intensities in the uninoculated seedlings, whereas a fifth PPO isoform appeared after inoculation with S. graminicola. PPO activity was significantly higher in the shoot and leaves of pearl millet than in the root. Tissue printing analysis of the enzyme expression showed that the enzyme is predominantly expressed after pathogen inoculation and is localised in the epidermal and vascular regions. Temporal analysis of transcript accumulation showed that in resistant seedlings PPO mRNAs was expressed earlier and more abundantly than in susceptible seedlings. Our studies demonstrate, for the first time, that PPO is actively involved in plant defence and can be used as a marker of resistance to downy mildew infection in pearl millet.
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Sayaslan, A., P. A. Seib, and O. K. Chung. "Wet-Milling of Flours from Red, White and Low-Polyphenol Oxidase White Wheats." Food Science and Technology International 11, no. 4 (August 2005): 243–49. http://dx.doi.org/10.1177/1082013205056778.
Full textAbstract:
Straight-grade and high-yield flours milled from red, white and low-polyphenol oxidase (PPO) activity white wheats were wet-milled to give gluten, starch, tailings and water-soluble fractions. Wet gluten fractions were either oven-dried or freeze-dried and ground to obtain dry gluten. White wheats yielded slightly more flour with higher lightness ( L*) than the red wheat. The wet-milling properties of all flours were comparable. The wet and oven-dried gluten fractions isolated from the low-PPO flours were the lightest, followed by the gluten fractions from the white and red wheat flours. The L* of the oven-dried gluten fractions from the low-PPO flours were ~ 1-3% higher than those from the white and red wheat flours. As the flour yield increased, the L* of the dry gluten fractions from all flours decreased likewise. However, the high-yield low-PPO white wheat flour gave the dry gluten with almost equal L* to the gluten isolated from the straight-grade red wheat flour, indicating the potential of the low-PPO white wheat flour in manufacturing brighter gluten.