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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.
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]
The general process of winemaking is initiated by the enzymatic oxidation of phenolic compounds by polyphenol oxidases. [4] Contact between the phenolic compounds in the vacuole of the grape cell and the polyphenol oxidase enzyme (located in the cytoplasm) triggers the oxidation of the grape. Thus, the initial browning of grapes occurs as a ...
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). Such browning can be prevented by cooking the fruit or lowering the pH (which destroys, inactivates, or denatures the enzyme) or by preventing oxygen from getting ...
l-DOPA, also known as l-3,4-dihydroxyphenylalanine and used medically as levodopa, is made and used as part of the normal biology of some plants [2] and animals, including humans. Humans, as well as a portion of the other animals that utilize l -DOPA, make it via biosynthesis from the amino acid l -tyrosine .
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.
3,4-Dihydroxyphenylacetaldehyde (DOPAL), also known as dopamine aldehyde, is a metabolite of the monoamine neurotransmitter dopamine formed by monoamine oxidase (MAO). [ 2 ] [ 3 ] Other metabolic pathways of dopamine metabolism include methylation by catechol O -methyltransferase (COMT) into 3-methoxytyramine and β-hydroxylation by dopamine β ...
A direct pathogenetic role of tyrosine hydroxylase has also been suggested, as the enzyme is a source of H 2 O 2 and other reactive oxygen species (ROS), and a target for radical-mediated injury. It has been demonstrated that L-DOPA is effectively oxidized by mammalian tyrosine hydroxylase, possibly contributing to the cytotoxic effects of L ...