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Revision as of 17:21, 11 March 2010
For dimers in statistical mechanics see dimer model. | This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Dimerization" – news · newspapers · books · scholar · JSTOR (April 2009) (Learn how and when to remove this message) |
A dimer is a chemical or biological entity consisting of two structurally similar subunits called monomers, which are joined by bonds, which can be strong or weak.
Organic chemistry
Molecular dimers are often formed by the reaction of two identical compounds e.g.: 2A → A-A. In this example, monomer "A" is said to dimerise to give the dimer "A-A". An example is Diaminocarbenes, which dimerise to give tetraaminoethylenes:
- 2 C(NR2)2 → (R2N)2C=C(NR2)2
Acetic acid forms a dimer in the gas phase, the monomer units are held together by hydrogen bonds. Under special conditions, most OH-containing molecules form dimers, e.g. the water dimer.
Dicyclopentadiene is a unsymmetrical dimer of two cyclopentadiene molecules have reacted to give the product. Upon heating, it "cracks" to give identical monomers:
- C10H12 → 2 C5H6
The term homodimer is used when the two molecules are identical (e.g. A-A) and heterodimer when they are not (e.g. A-B). The reverse of dimerisation is often called dissociation.
Biochemistry
In biochemistry and molecular biology, dimers of macromolecules like proteins and nucleic acids are often observed. The dimerization of identical subunits is called homodimerization; the dimerization of different subunits or unrelated monomers is called heterodimerization. Most dimers in biochemistry are not connected by covalent bonds with the exception of disulfide bridges. An example of this would be the enzyme reverse transcriptase, which is made of two different amino acid chains.
Examples
- DNA
- Antibodies
- Transcription factors
- Leucine zipper motif proteins
- Nuclear receptors
- 14-3-3 proteins
- G protein-coupled receptors
- G protein βγ-subunit dimer
- Kinesin
- Triosephosphateisomerase (TIM)
- Alcohol dehydrogenase
- Factor XI
- Factor XIII
- Toll-like receptor
- Fibrinogen
Plants
Dimerous refer to plants with organ arrangement based on the number 2, see : merosity.
See also
- di, a prefix
- -mer, a suffix
- Dimer model
References
- "IUPAC "Gold Book" definition". Retrieved 2009-04-30.
- "Structure-Activity Relationships of - 3'-spiro-5' '-(4' '-amino-1' ',2' '-oxathiole-2' ',2' '-dioxide)thymine Derivatives as Inhibitors of HIV-1 Reverse Transcriptase Dimerization". J. Med. Chem. 49 (16): 4834–4841. 2006. doi:10.1021/jm0604575.
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