What Is a Chromophore?

A chromophore refers to an unsaturated group contained in a molecule that can absorb light radiation and has transitions and related chemical bonds. There are groups containing unsaturated bonds in some organic compound molecules, which can generate absorption in the ultraviolet and visible light regions (200-800nm), and the absorption coefficient is large. This absorption has wavelength selectivity and absorbs a certain wavelength (color ), Without absorbing light of another wavelength (color), so that the substance appears in color, so it is called a chromophore, also known as a chromophore.

Molecular absorption usually manifests as n * and * transitions, so the absorption range is mostly between 200-800nm. If the molecule contains two or more conjugated chromophores, the molecule's absorption of light moves towards

This type

Can be used for color reaction

The chromophore of green fluorescent protein is composed of three consecutive amino acids. In wild-type green fluorescent protein, it is composed of Ser-Tyr-Gly at positions 65, 66, and 67, respectively. Previous research generally believed that the formation of fluorescent groups in green fluorescent proteins first required that the polypeptide chain be folded into a structure close to the natural conformation. After the folding was completed, the amino nitrogen N67 of Gly67 nucleophilically attacked the carbonyl carbon C65 on Ser65, cyclized to form an unstable five-membered heterocyclic intermediate, and then dehydrated and oxidized to form a chromophore ^[2] . However, Wachter et al. Reported in 2006 that another possible mechanism is that the process of forming unstable five-membered heterocyclic intermediates is reversible, and the next process is the intermediates are first oxidized and then dehydrated. More reliable experimental support. In the former mechanism, Heim and Pransher et al. Proposed that when a cyclized intermediate is formed, the intermediate is first dehydrated, and then a hydrogen on C66 is removed under the action of oxygen molecules to form a chromophore and simultaneously produce a Molecule H2O2. In the mechanism proposed by Wachter et al., The intermediate 1 formed by cyclization forms a stable intermediate 2B under the action of molecular oxygen, and simultaneously produces a molecule of H2O2. Then the intermediate 2B loses a hydrogen on C66 by dehydration. To form a chromophore. The reason they proposed this mechanism was that by replacing the hydrogen on C66 with deuterium, they found that dehydrogenation did not occur during the oxidation stage ^[3] .