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Polyphenol oxidase is an enzyme found throughout the plant and animal kingdoms, [31] including most fruits and vegetables. [32] PPO has importance to the food industry because it catalyzes enzymatic browning when tissue is damaged from bruising, compression or indentations, making the produce less marketable and causing economic loss.
Peroxidase activity is measured by running the phenol oxidase assay concurrently with another assay with L-DOPA and hydrogen peroxide (H 2 O 2) added to every sample. [48] The difference in measurements between the two assays is indicative of peroxidase activity. Enzyme assays typically apply proxies that reveal exo-acting activities of enzymes.
Chelating agents − Polyphenol oxidase requires copper as a cofactor for its functionality, thus copper-chelating agents inhibit the activity of this enzyme. Many agents possessing chelating activity have been studied and used in different fields of food industry, such as citric acid , sorbic acid , polyphosphates , hinokitiol , kojic acid ...
Catechol oxidase is a copper oxidase that contains a type 3 di-copper cofactor and catalyzes the oxidation of ortho-diphenols into ortho-quinones coupled with the reduction of molecular oxygen to water. It is present in a variety of species of plants and fungi including Ipomoea batatas (sweet potato) [1] and Camellia sinensis (Indian tea leaf). [2]
[1] [2] They increase the rate at which ATP is produced aerobically. Oxidative enzymes are responsible for the browning of fruits like apples. When the surface of apples are exposed to the oxygen in the air, the oxidative enzymes like polyphenol oxidase and catechol oxidase oxidize the fruit (electrons are lost to the air).
[2] Probing this PLP-catalyzed decarboxylation, it has been discovered that there is a difference in concentration and pH dependence between substrates. DOPA is optimally decarboxylated at pH 6.7 and a PLP concentration of 0.125 mM, while the conditions for optimal 5-HTP decarboxylation were found to be pH 8.3 and 0.3 mM PLP. [3]
3,4-Dihydroxyphenylacetic acid (DOPAC) is a metabolite of the neurotransmitter dopamine.Dopamine can be metabolized into one of three substances. One such substance is DOPAC.
L-DOPA (S), 3,4-dihydroxyphenylalanine, a precursor of a neurotransmitter This page was last edited on 30 March 2021, at 01:24 (UTC). Text is available under the ...