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Names | |
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Preferred IUPAC name N′-(3,4-Dichlorophenyl)-N,N-dimethylurea | |
Other names 3-(3,4-Dichlorophenyl)-1,1-dimethylurea, Karmex, Diuron, Direx | |
Identifiers | |
3D model (JSmol) | |
ChEBI | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.005.778 |
EC Number |
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KEGG | |
PubChem CID | |
RTECS number |
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UNII | |
UN number | 3077, 2767 |
CompTox Dashboard (EPA) | |
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Properties | |
C9H10Cl2N2O | |
Molar mass | 233.09 g·mol−1 |
Appearance | white crystalline solid [1] |
Density | 1.48 g/cm3 |
Melting point | 158 °C (316 °F; 431 K) |
Boiling point | 180 °C (356 °F; 453 K) |
42 mg/L | |
Vapor pressure | 0.000000002 mmHg (20°C) [1] |
Hazards | |
GHS labelling: | |
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Warning | |
H302, H351, H373, H410 | |
P201, P202, P260, P264, P270, P273, P281, P301+P312, P308+P313, P314, P330, P391, P405, P501 | |
Flash point | noncombustible [1] |
NIOSH (US health exposure limits): | |
PEL (Permissible) | none [1] |
REL (Recommended) | TWA 10 mg/m3 [1] |
IDLH (Immediate danger) | N.D. [1] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea) is an algicide and herbicide of the arylurea class that inhibits photosynthesis. It was introduced by Bayer in 1954 under the trade name of Diuron.
In 1952, chemists at E. I. du Pont de Nemours and Company patented a series of aryl urea derivatives as herbicides. Several compounds covered by this patent were commercialized as herbicides: chlortoluron (3-chloro-4-methylphenyl) and DCMU, the (3,4-dichlorophenyl) example. [2] [3] Subsequently, over thirty related urea analogs with the same mechanism of action reached the market worldwide. [4]
As described in the du Pont patent, the starting material is 3,4-dichloroaniline, which is treated with phosgene to form a isocyanate derivative. This is subsequently reacted with dimethylamine to give the final product. [2]
DCMU is a very specific and sensitive inhibitor of photosynthesis. It blocks the QB plastoquinone binding site of photosystem II, disallowing the electron flow from photosystem II to plastoquinone. [5] This interrupts the photosynthetic electron transport chain in photosynthesis and thus reduces the ability of the plant to turn light energy into chemical energy (ATP and reductant potential).
DCMU only blocks electron flow from photosystem II, it has no effect on photosystem I or other reactions in photosynthesis, such as light absorption or carbon fixation in the Calvin cycle.[ citation needed ]
However, because it blocks electrons produced from water oxidation in PS II from entering the plastoquinone pool, "linear" photosynthesis is effectively shut down, as there are no available electrons to exit the photosynthetic electron flow cycle for reduction of NADP+ to NADPH. In fact, it was found that DCMU not only does not inhibit the cyclic photosynthetic pathway, but, under certain circumstances, actually stimulates it. [6] [7]
Because of these effects, DCMU is often used to study energy flow in photosynthesis.
DCMU (Diuron) has been characterized as a known/likely human carcinogen based on animal testing. [8] [9]
Photosynthesis is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their activities. Photosynthetic organisms use intracellular organic compounds to store the chemical energy they produce in photosynthesis within organic compounds like sugars, glycogen, cellulose and starches. Photosynthesis is usually used to refer to oxygenic photosynthesis, a process that produces oxygen. To use this stored chemical energy, the organisms' cells metabolize the organic compounds through another process called cellular respiration. Photosynthesis plays a critical role in producing and maintaining the oxygen content of the Earth's atmosphere, and it supplies most of the biological energy necessary for complex life on Earth.
Thylakoids are membrane-bound compartments inside chloroplasts and cyanobacteria. They are the site of the light-dependent reactions of photosynthesis. Thylakoids consist of a thylakoid membrane surrounding a thylakoid lumen. Chloroplast thylakoids frequently form stacks of disks referred to as grana. Grana are connected by intergranal or stromal thylakoids, which join granum stacks together as a single functional compartment.
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 as well as analogs such as PQ-B, PQ-C, and PQ-D, which differ in their side chains. 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.
Photosystems are functional and structural units of protein complexes involved in photosynthesis. Together they carry out the primary photochemistry of photosynthesis: the absorption of light and the transfer of energy and electrons. Photosystems are found in the thylakoid membranes of plants, algae, and cyanobacteria. These membranes are located inside the chloroplasts of plants and algae, and in the cytoplasmic membrane of photosynthetic bacteria. There are two kinds of photosystems: PSI and PSII.
Photosystem II is the first protein complex in the light-dependent reactions of oxygenic photosynthesis. It is located in the thylakoid membrane of plants, algae, and cyanobacteria. Within the photosystem, enzymes capture photons of light to energize electrons that are then transferred through a variety of coenzymes and cofactors to reduce plastoquinone to plastoquinol. The energized electrons are replaced by oxidizing water to form hydrogen ions and molecular oxygen.
Photosystem I is one of two photosystems in the photosynthetic light reactions of algae, plants, and cyanobacteria. Photosystem I is an integral membrane protein complex that uses light energy to catalyze the transfer of electrons across the thylakoid membrane from plastocyanin to ferredoxin. Ultimately, the electrons that are transferred by Photosystem I are used to produce the moderate-energy hydrogen carrier NADPH. The photon energy absorbed by Photosystem I also produces a proton-motive force that is used to generate ATP. PSI is composed of more than 110 cofactors, significantly more than Photosystem II.
In the process of photosynthesis, the phosphorylation of ADP to form ATP using the energy of sunlight is called photophosphorylation. Cyclic photophosphorylation occurs in both aerobic and anaerobic conditions, driven by the main primary source of energy available to living organisms, which is sunlight. All organisms produce a phosphate compound, ATP, which is the universal energy currency of life. In photophosphorylation, light energy is used to pump protons across a biological membrane, mediated by flow of electrons through an electron transport chain. This stores energy in a proton gradient. As the protons flow back through an enzyme called ATP synthase, ATP is generated from ADP and inorganic phosphate. ATP is essential in the Calvin cycle to assist in the synthesis of carbohydrates from carbon dioxide and NADPH.
The cytochrome b6f complex (plastoquinol/plastocyanin reductase or plastoquinol/plastocyanin oxidoreductase; EC 7.1.1.6) is an enzyme found in the thylakoid membrane in chloroplasts of plants, cyanobacteria, and green algae, that catalyzes the transfer of electrons from plastoquinol to plastocyanin:
Chlortoluron or chlorotoluron are the common names for an organic compound of the phenylurea class of herbicides used to control broadleaf and annual grass weeds in cereal crops.
A photosynthetic reaction center is a complex of several proteins, pigments, and other co-factors that together execute the primary energy conversion reactions of photosynthesis. Molecular excitations, either originating directly from sunlight or transferred as excitation energy via light-harvesting antenna systems, give rise to electron transfer reactions along the path of a series of protein-bound co-factors. These co-factors are light-absorbing molecules (also named chromophores or pigments) such as chlorophyll and pheophytin, as well as quinones. The energy of the photon is used to excite an electron of a pigment. The free energy created is then used, via a chain of nearby electron acceptors, for a transfer of hydrogen atoms (as protons and electrons) from H2O or hydrogen sulfide towards carbon dioxide, eventually producing glucose. These electron transfer steps ultimately result in the conversion of the energy of photons to chemical energy.
P700, or photosystem I primary donor, is a molecular dimer of chlorophyll a associated with the reaction-center of photosystem I in plants, algae, and cyanobacteria.
In enzymology, a ferredoxin-NADP+ reductase (EC 1.18.1.2) abbreviated FNR, is an enzyme that catalyzes the chemical reaction
Propanil is a widely used contact herbicide. With an estimated use of about 8 million pounds in 2001, it is one of the more widely used herbicides in the United States. Propanil is said to be in use in approximately 400,000 acres of rice production each year.
Tenuazonic acid is a mycotoxin produced by Alternaria species. It is a powerful eukaryotic protein synthesis inhibitor. It is a tetrameric acid that is ubiquitous in biological environments and prevents the release of newly synthesized protein from the ribosome. Its toxicity is the highest among all Alternaria mycotoxins and has both phytotoxic and cytotoxic properties. In 1991 Tenuazonic acid was reported to inhibit skin tumor promotion in mice.
Light-dependent reactions are certain photochemical reactions involved in photosynthesis, the main process by which plants acquire energy. There are two light dependent reactions: the first occurs at photosystem II (PSII) and the second occurs at photosystem I (PSI).
Metribuzin is a herbicide used both pre- and post-emergence in crops including soy bean, potatoes, tomatoes and sugar cane.
Chlororespiration is a respiratory process that takes place within plants. Inside plant cells there is an organelle called the chloroplast which is surrounded by the thylakoid membrane. This membrane contains an enzyme called NAD(P)H dehydrogenase which transfers electrons in a linear chain to oxygen molecules. This electron transport chain (ETC) within the chloroplast also interacts with those in the mitochondria where respiration takes place. Photosynthesis is also a process that Chlororespiration interacts with. If photosynthesis is inhibited by environmental stressors like water deficit, increased heat, and/or increased/decreased light exposure, or even chilling stress then chlororespiration is one of the crucial ways that plants use to compensate for chemical energy synthesis.
Plastid terminal oxidase or plastoquinol terminal oxidase (PTOX) is an enzyme that resides on the thylakoid membranes of plant and algae chloroplasts and on the membranes of cyanobacteria. The enzyme was hypothesized to exist as a photosynthetic oxidase in 1982 and was verified by sequence similarity to the mitochondrial alternative oxidase (AOX). The two oxidases evolved from a common ancestral protein in prokaryotes, and they are so functionally and structurally similar that a thylakoid-localized AOX can restore the function of a PTOX knockout.
Linuron is a phenylurea herbicide that is used to control the growth of grass and weeds for the purpose of supporting the growth of crops like soybeans.
Cyanazine is a herbicide that belongs to the group of triazines. Cyanazine inhibits photosynthesis and is therefore used as a herbicide.