A dimer is a molecule or a molecule composite which consists of two identical subunits often, the monomers. With respect to the size, molecular weight and complexity of the dimer is the simplest oligomer or polymer. The process of dimer formation is called dimerization.
Homodimers and heterodimers
Dimers are divided into homo-and heterodimers. In a homodimer, the two monomers are identical. In a heterodimer, the two monomers are different, but often very similar.
Link types in dimers
The subunits in dimers can be interconnected differently. The most common type is the covalent attachment (via atomic bonds ). Strongly polar compounds or proteins can also form non-covalent dimers, in which Van der Waals, dipole, electrostatic and hydrophobic interactions and hydrogen bonds for the cohesion play a crucial role.
- Atoms of the 1 (hydrogen and lithium), 5 (nitrogen ) 6 (oxygen) and Group 7 ( halogens such as fluorine and chlorine) of the periodic table forming covalent homodimers.
- Complexes of transition metals include the proofreading together to form dimers. Most linkage via a multiple bond takes place.
- Some - mostly organic - compounds form homodimers by intramolecular hydrogen bonds, such as acetic acid.
- The most common dimers are various types of sugars; e.g. Sucrose is a heterodimer of a glucose and fructose molecule; Cellobiose, however, is a homodimer of two glucose units. These dimers are called disaccharides ( double sugars outdated ) refers.
- Proteins can be used as di-or oligomers consist of several polypeptide chains. This occurs to a dimer of a polymeric compound, such as the I or the Fumarasen phytochromes.
- Specifically, the DNA can be obtained by the mutagenic effect of the UV light, a thymine dimer, which is a dimer between two adjacent thymine bases, occur, which may lead to an error in the replication.