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- Groups in molecules which influence the absorption behaviour of the compound in a characteristic way (chromos =colour; phoros = carrier). Chromophores, i.e. colour carriers, are responsible for the colour of a substance, e.g. also of the skin (see below skin colour).
- In the actual sense, however, the term chromophore is only used to describe the part of a substance which is responsible for the colour itself (colour carrier). In organic dyes these are mostly systems of conjugated double bonds. In common parlance, however, the whole molecule is also called chromophore, e.g. melanin.
- The absorption spectrum of the molecule group does not always have to be in the visible range; it can also be in the UV spectral range (UV chromophores). Thus, in a broader sense, organic molecular structures that translate UV rays into molecular processes are also counted as chromophores.
- UV-chromophores show a good absorption behaviour in the spectral range of UV-rays or even an absorption maximum in this range. They either absorb the energy of ultraviolet light, remain unchanged (energy is emitted as heat or phosphorescence/fluorescence) or cause molecular changes in themselves or in the environment (such changed molecules are called photo products).
- The best known UV chromophore is melanin. An important UV chromophore is DNA itself. Its absorption maximum is 260nm. 7-dehydrocholesterol is another UV-chromophore, its photoproduct is vitamin D. Furthermore the amino acids tryptophan (photoproduct = the tryptophan dimer FICZ) and tyrosine as well as urocanic acid have absorption values between 240 nm and 300 nm (UV spectrum). Among other things, the degradation product of azathioprine, 6-thioguanine, acts as a chromophore. When incorporated into the DNA, it induces chromosome strand breaks upon UVA irradiation.
LiteratureThis section has been translated automatically.
- Brem R et al (2010) DNA breakage and cell cycle checkpoint abrogation induced by a therapeutic thiopurine and UVA radiation. Oncogene 29:3953-3963
- Esser C et al (2010) UV radiation and pigmentation, dermatologist 61: 561-566
- Giehl K et al (2010) Genetically caused pigmentation disorders. Dermatologist 61:567-577.