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Chemical compound
Plastoquinone (PQ) is a terpenoid-quinone (meroterpenoid) molecule involved in the electron transport chain in the light-dependent reactions of photosynthesis. The most common form of plastoquinone, known as PQ-A or PQ-9, is a 2,3-dimethyl-1,4-benzoquinone molecule with a side chain of nine isoprenyl units. There are other forms of plastoquinone, such as ones with shorter side chains like PQ-3 (which has 3 isoprenyl side units instead of 9) as well as analogs such as PQ-B, PQ-C, and PQ-D, which differ in their side chains.[1] The benzoquinone and isoprenyl units are both nonpolar, anchoring the molecule within the inner section of a lipid bilayer, where the hydrophobic tails are usually found.[1]
Plastoquinones are very structurally similar to ubiquinone, or coenzyme Q10, differing by the length of the isoprenyl side chain, replacement of the methoxy groups with methyl groups, and removal of the methyl group in the 2 position on the quinone. Like ubiquinone, it can come in several oxidation states: plastoquinone, plastosemiquinone (unstable), and plastoquinol, which differs from plastoquinone by having two hydroxyl groups instead of two carbonyl groups.[2]
Plastoquinol, the reduced form, also functions as an antioxidant by reducing reactive oxygen species, some produced from the photosynthetic reactions, that could harm the cell membrane.[3] One example of how it does this is by reacting with superoxides to form hydrogen peroxide and plastosemiquinone.[3]
The reduction (from left to right) of plastoquinone (PQ) to plastosemiquinone (PQH.) to plastoquinol (PQH2).
The prefix plasto- means either plastid or chloroplast, alluding to its location within the cell.[4]
^ abNowicka, Beatrycze; Kruk, Jerzy (2010-09-01). "Occurrence, biosynthesis and function of isoprenoid quinones". Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1797 (9): 1587–1605. doi:10.1016/j.bbabio.2010.06.007. ISSN 0006-3002. PMID 20599680.
^Tikhonov, Alexander N. (2014-08-01). "The cytochrome b6f complex at the crossroad of photosynthetic electron transport pathways". Plant Physiology and Biochemistry. 81: 163–183. doi:10.1016/j.plaphy.2013.12.011. ISSN 1873-2690. PMID 24485217.
^ abMubarakshina, Maria M.; Ivanov, Boris N. (2010-10-01). "The production and scavenging of reactive oxygen species in the plastoquinone pool of chloroplast thylakoid membranes". Physiologia Plantarum. 140 (2): 103–110. doi:10.1111/j.1399-3054.2010.01391.x. ISSN 1399-3054. PMID 20553418.
^http://dictionary.reference.com/browse/Plastoquinone Definition of plastoquinone
Plastoquinone (PQ) is a terpenoid-quinone (meroterpenoid) molecule involved in the electron transport chain in the light-dependent reactions of photosynthesis...
Photosystem II (or water-plastoquinone oxidoreductase) is the first protein complex in the light-dependent reactions of oxygenic photosynthesis. It is...
series of experiments to demonstrate that it is pheophytin and not plastoquinone that serves as the primary electron acceptor in photosystem II. Using...
the denomination of a cationic derivative of the plant antioxidant plastoquinone. In 1969, triphenylphosphonium (TPP, charged triphenylphosphine) was...
shuttle electrons between them. These carriers are plastoquinone and plastocyanin. Plastoquinone shuttles electrons from photosystem II to the cytochrome...
It blocks the QB plastoquinone binding site of photosystem II, disallowing the electron flow from photosystem II to plastoquinone. This interrupts the...
passes from the primary electron acceptor to ferredoxin and then to plastoquinone, next to cytochrome b6f (a similar complex to that found in mitochondria)...
there is an homologous protein, cytochrome b6, a component of the plastoquinone-plastocyanin reductase (EC 1.10.99.1), also known as the b6f complex...
naturally occurring 1,4-benzoquinone involved in respiration apparatus. Plastoquinone is a redox relay involved in photosynthesis. Pyrroloquinoline quinone...
PTOX knockout. Plastid terminal oxidase catalyzes the oxidation of the plastoquinone pool, which exerts a variety of effects on the development and functioning...
are transferred to protein-bound plastoquinone (PQA) and then to unbound plastoquinone (PQB). This reduces plastoquinone (PQ) to plastoquinol (PQH2) which...
code C01EB09 (WHO) Related compounds Related quinones 1,4-Benzoquinone Plastoquinone Ubiquinol Except where otherwise noted, data are given for materials...
functional group is used in the formation of chlorophyll a, ubiquinones, plastoquinone and phylloquinone. Diterpenes are formally defined as being hydrocarbons...
captures electrons from photosystem II through a series of steps involving plastoquinone, cytochromes, and plastocyanin. Oxidized photosystem II oxidizes the...
transport chain has many electron acceptors including pheophytin, quinone, plastoquinone, cytochrome bf, and ferredoxin, which result finally in the reduced...
(now a plastoquinone), and that another was from cytochrome f to a step in the carbohydrate-generating mechanisms. These are linked by plastoquinone, which...
plants, HPPD is necessary for the biosynthesis of tocopherols and of plastoquinone, which is essential to carotenoid production. Inhibiton of the pathway...
and later to CoQ'−•) In chloroplasts, a similar reaction is done with plastoquinone by cytochrome b6f complex. Operation of the modified Q cycle in Complex...
qualification, in pharmaceutics, part of verification and validation Plastoquinone, a molecule involved in photosynthesis PQ International, a polo magazine...
series of redox reactions onto plastoquinone. Photosystem II therefore has also been referred to as water-plastoquinone oxido-reductase. The protons split...
They use mobile, lipid-soluble quinone carriers (phylloquinone and plastoquinone) and mobile, water-soluble carriers (cytochromes). They also contain...
Like other triazine herbicides, atrazine functions by binding to the plastoquinone-binding protein in photosystem II, which animals lack. Plant death results...
synthesis and metabolism. They contain many types of lipids including plastoquinone, vitamin E, carotenoids and chlorophylls. Plastoglobuli were once thought...
own plastoquinone pool. Plastoquinone (PQ) is an essential protein in the electron transfer system, and by limiting the amount of plastoquinone available...
evolution: analysis of structure and function of photosystem II, the water-plastoquinone oxido-reductase". Photosynthesis Research. 85 (3): 267–93. doi:10...
transcription according to the redox state of the electron carrier plastoquinone. These genes code for photosynthetic reaction centers and other components...
isoprenoids (carotenoids, sterols, prenyl side-chains of chlorophylls and plastoquinone) via a novel pyruvate/glyceraldehyde 3-phosphate non-mevalonate pathway...
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