DCMU

DCMU
Other names 3-(3,4-Dichlorophenyl)-1,1-dimethylurea
Identifiers
CAS number	330-54-1 Y
ChemSpider	3008 Y
KEGG	C18428 Y
ChEBI	CHEBI:116509 Y
ChEMBL	CHEMBL278489 Y
Jmol-3D images	Image 1
SMILES Clc1ccc(NC(=O)N(C)C)cc1Cl
InChI InChI=1S/C9H10Cl2N2O/c1-13(2)9(14)12-6-3-4-7(10)8(11)5-6/h3-5H,1-2H3,(H,12,14) Y Key: XMTQQYYKAHVGBJ-UHFFFAOYSA-N Y InChI=1/C9H10Cl2N2O/c1-13(2)9(14)12-6-3-4-7(10)8(11)5-6/h3-5H,1-2H3,(H,12,14) Key: XMTQQYYKAHVGBJ-UHFFFAOYAZ
Properties
Molecular formula	C9H10Cl2N2O
Molar mass	233.09 g mol−1
Density	1.48 g/cm3
Melting point	158 °C, 431 K, 316 °F
Boiling point	180 °C, 453 K, 356 °F
Solubility in water	42 mg/L
Hazards
EU classification	Harmful (Xn); Dangerous for the environment (N)
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea) is an herbicide that inhibits photosynthesis. It was introduced by Bayer in 1954 under the trade name of Diuron.

Mechanism of action

DCMU is a very specific and sensitive inhibitor of photosynthesis. It blocks the plastoquinone binding site of photosystem II, disallowing the electron flow from where it is generated, in photosystem II, to plastoquinone.^[1] This interrupts the photosynthetic electron transport chain in photosynthesis and thus blocks 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.

However, because it absorbs electrons oxidized from water in PS II, the electron "hole" of PS I cannot be satisfied, effectively shutting down photosynthesis by blocking the reduction of NADP⁺ to NADPH, and the cyclic photosynthetic pathway since electron shuttling is associated with proton pumping across the membrane into the lumen.

Because of these effects, DCMU is often used to study energy flow in photosynthesis.

References

1. ^ Metz, J; Pakrasi, H; Seibert, M; Arntzer, C (1986). "Evidence for a dual function of the herbicide-binding D1 protein in photosystem II". FEBS Letters 205 (2): 269. doi:10.1016/0014-5793(86)80911-5.