Dimerisaation

Dimerisation, also spelled dimerization, is the process by which two molecular units, or monomers, associate to form a dimer. The connection between the two subunits may be covalent, resulting in a single molecule carrying two connected units, or non-covalent, held together by hydrogen bonds, ionic interactions, van der Waals forces, or hydrophobic effects. Dimerisation is a common phenomenon in chemistry, biochemistry, and materials science and can affect properties such as solubility, stability, reactivity, and regulatory behavior.

Covalent dimerisation creates a permanent bond between the monomers, often through oxidative coupling or enzymatic linking. Non-covalent dimerisation is typically reversible and driven by ambient conditions such as concentration, temperature, and solvent. In many systems, dimerisation occurs as an early or essential step in larger aggregation processes or signaling pathways.

Examples can be found in biology, chemistry, and materials science. In biology, receptor proteins such as certain tyrosine kinases dimerize upon ligand binding, triggering downstream signaling. Many transcription factors form functional dimers that regulate DNA binding. In chemistry, photodimerisation describes a light-induced, non-covalent or covalent linkage between two alkene units, often via cycloaddition. Dimerisation also appears in polymerization contexts, where dimers act as intermediates in step-growth processes or in the stabilization of reactive species.

The significance of dimerisation lies in its effects on activity, specificity, and stability. It is studied using techniques such as spectroscopy, mass spectrometry, size-exclusion chromatography, and analytical ultracentrifugation, which help quantify association constants and characterize the nature of the dimer.