Phenoloxidases of perennial plants: Hydroxylase activity, isolation and physiological role

Omiadze, N. T.; Mchedlishvili, N. I.; Abutidze, M. O.

doi:10.1016/j.aasci.2018.03.009

Cited by 6 publications

(5 citation statements)

References 42 publications

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“…Observations and results collated from the students' outputs showed the activity of PPO in apples (Malus domestica), potatoes (Solanum tuberosum L.), eggplant (Solanum melongena), sweet potato (Ipomoea batatas), and banana (Musa acuminata × balbisiana) as evident in the browning response of control samples after exposure to air. This browning occurs on the cut or damaged tissues of samples when phytomelanins are produced from the polymerization of PPO-generated quinones 18 . Several studies have quantified the PPO activity of apple (762, 666.67 U) 1 , potato (52,857.14 U) 19 , eggplant (2, 894 U) 20 , sweet potato (43, 400 U) and banana (141, 600 U) 21 .…”

Section: Resultsmentioning

confidence: 99%

Enzymatic Activity of Polyphenol Oxidase: A Laboratory Experiment in Flexible Learning

Duldulao

2023

Orient. J. Chem

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Polyphenol oxidases (PPO) are enzymes that catalyze the browning of fruits and vegetables when oxygen in the air reacts with the present phenolic compounds. This study demonstrates the enzymatic browning of food samples and the inhibition of its activity by common household materials. Fresh food samples were tested in different treatments of acidic and ionic solutions, and syrups. Observations from the students’ work showed that changes in pH, surface area for the site of reaction, and ionic conditions affect enzymatic browning. The deviation from the optimum working pH, introduction of ionic interaction, and alteration of the surface area led to the interruption of the interaction within the enzyme structure and between its active site and the substrate thereby inhibiting the enzyme function. Results of the experiment can also serve as a basis for further studies on the development of methods and products to inhibit PPO action and maintain the sensory value and nutritional quality of foods. Furthermore, experiments of similar nature can be crafted as practical activities and alternative teaching techniques designed for students to apply chemistry concepts and laboratory fundamentals to the conduct of an experiment suited for the flexible learning set- up.

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Section: Resultsmentioning

confidence: 99%

Enzymatic Activity of Polyphenol Oxidase: A Laboratory Experiment in Flexible Learning

Duldulao

2023

Orient. J. Chem

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“…Tyrosine hydroxylase can convert tyrosine to o-diphenols, whereas phenoloxidase can convert o-diphenols to quinones [70] . The phenoloxidases of perennial plants have hydroxylase activity [71] . In a pH-dependent manner, the heme-phage (capsid) complex oxidizes a variety of peroxidase substrates, including the catechol derivative di-tert-butylcatechol [72] .…”

Section: Introductionmentioning

confidence: 99%

COVID-19: Attacks the 1-Beta Chain of Hemoglobin to Disrupt Respiratory Function and Escape Immunity by Capsid-Like System

Liu

2023

Preprint

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The genetic recombination of the SARs-CoV-2 virus in bats may result in behaviors comparable to those of certain RNA viruses. This cross-activity helps explain SARs-CoV-2's strange respiratory symptoms and immune evasion abilities. In this present study, the biological roles of SARs-CoV-2 proteins were investigated utilizing bioinformatic techniques involving the search for conserved domains. According to the study, the S and ORF3a proteins of SARs-CoV-2 possess picornavirus/calicivirus capsid domains, can bind hemoglobin, heme, and porphyrin. Both Arg134 of ORF3a and Cys44 of E are iron-binding sites for heme. The ORF3a protein has a region that converts heme into iron and porphyrin. In addition to chitin and polyphenol binding domains, the S protein also contains hemocyanin and phenoloxidase-like domains. The S protein constructs Fe-polyphenol complexes to link the red blood cell membrane, allowing SARs-CoV-2 to hitch a ride on red blood cells for fast delivery to target organs. This type of capsid-like vector delays the immune system but does not significantly alter the function of red blood cells to transport oxygen. Due to the distortion of the cell membrane, red blood cells with an excess of viral particles release hemoglobin to harm the virus. The wbl domains of the S protein respond to nitration, and then phenoloxidase domains oxidize polyphenols, allowing the virus to shed from the red blood cell membrane. ORF3a also attack 1-beta chain of hemoglobin; however, the majority of hemoglobin may retain its native structure. Patients will have variable degrees of respiratory distress and coagulation symptoms, but the hemocyanin domains of the S protein can improve a patient's respiratory status by transporting oxygen.

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“…From the perspective of their biosynthesis, an especially important key enzyme is phenylalanine ammonia lyase, which can be induced by various stressful (ecological) conditions (Jun et al, 2018;Gho et al, 2019;Fan et al, 2022). Furthermore, polyphenol oxidases and peroxidases are the main enzymes responsible for loss of quality due to phenol degradation (Araji et al, 2014;Omiadze et al, 2018;Chen & Vierling, 2022). The literature considers various factors that have effects on quality of food products, which are related to changes in phenol composition in plants (Dicko et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Key role of phenol enzymes metabolism in the legume-rhizobial symbiosis under different water supply regimes

Nyzhnyk,

Kots

2023

Biosys. divers.

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The legume-rhizobium interaction induces formation of specific reactions that take metabolism in the host plant up to a new functional level, increasing its tolerance to unfavourable cultivation conditions. Our objective was to study the participation of key enzymes – phenylalanine ammonia lyase, guaiacol peroxidase, and polyphenol oxidases – in the phenol-metabolism processes and synthesis of a broad spectrum of secondary metabolites in soybean plants that have established symbiotic interactions with rhizobia of varying effectiveness during optimal and insufficient water supplies. In our studies, we used symbiotic systems of soybean and rhizobia (Bradyrhizobium japonicum) that varied in efficiency and virulence. In the period of active nitrogen fixation by soybean, from the third-true-leaf stage until budding, we created different water-supply regimes for the plants, including optimal watering at the level of 60% of full field capacity (control) and insufficient, at the level of 30% (drought). When the soybean was flowering, we recovered the optimal level of water supply (resumed watering). In the studies, we employed microbiological, biochemical, and physiological approaches. We determined the specificity of how key enzymes of the phenol metabolism such as phenylalanine ammonia lyase, polyphenol oxidase and guaiacol peroxidase in the nodules, roots, and leaves of the soybean reacted to different levels of water supply, depending on the functional efficiency of the symbiotic system involving strains of B. japonicum, varying in effectiveness and virulence. In the effective soybean-rhizobium symbiosis, there occurred insignificant changes in the activity of phenol-metabolism enzymes in the nodules, roots, and leaves during drought and after action of the stress. This evidence is that in symbiosis with effective rhizobia B1-20, soybean could realize its own defensive systems that regulate optimal functioning of phenol metabolism in dehydration conditions. In the low-effective 107 and ineffective 604k symbiotic systems of soybean, there was observed unstable dynamics of the activity of enzymes in leaves and roots, manifested in intensification or inhibition of their activity levels during drought or post-stress period. This indicates malfunctioning of the processes associated with phenol metabolism in the soybean plants. We concluded that tolerance of legume-rhizobium symbiosis to water deprivation depends on mutual involvements of the both symbiotic partners – host plant and rhizobia, their ability to fully realize the defensive systems for activation of the key enzymatic complexes taking part in regulation of phenol metabolism in plants.

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Phenoloxidases of perennial plants: Hydroxylase activity, isolation and physiological role

Cited by 6 publications

References 42 publications

Enzymatic Activity of Polyphenol Oxidase: A Laboratory Experiment in Flexible Learning

Enzymatic Activity of Polyphenol Oxidase: A Laboratory Experiment in Flexible Learning

COVID-19: Attacks the 1-Beta Chain of Hemoglobin to Disrupt Respiratory Function and Escape Immunity by Capsid-Like System

Key role of phenol enzymes metabolism in the legume-rhizobial symbiosis under different water supply regimes

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