Fluorophores coumarin derivatives

The wide variety of absorption and emission wavelengths has allowed the use of different coumarin derivatives as FRET pairs [37], Contrary to most fluorophores, coumarin is uncharged which makes it intrinsically membrane-permeant. To induce water solubility polar groups are frequently introduced to the basic structure [35],... 

The spectral properties of this fluorophore are similar to those of other coumarin derivatives. The excitation maximum occurs at about 382nm and its emission peak at 472nm, producing light in the blue region of the spectrum. The extinction coefficient of DCIA at its wavelength of maximum absorbance, 382nm, is 33,000 M em-1 (in methanol). 

The chemical principles applied in the labelling of acidic functions using fluorescent coumarin derivatives were also used in conjunction with other fluorophores. The conditions of the alkylation reactions are therefore the same. Consequently, these reagents suffer equally from a lack of selectivity usually all acidic functions (carboxyl, phenol, thiol, imide and hydroxyl) can be brought to reaction. 

Release fluorolmmunoassay makes use of an antigen or a hapten, respectively, conjugated through ester or glycosidic bonds to a fluorophore (e.g., a coumarine derivative). The conjugate is nonfluorescent because of quenching effects of the substituent. Hydrolysis of the bond catalyzed by the binding of antibodies releases the fluorophore. 

There are many fluorophores used in antibody labelling such as rhodamine, coumarin derivatives, phycobiliproteins, and rare earth chelates, however fluorescein is probably the most widely used. Individual choice may be determined by the optical filters available for the microscope or other detector. Protocol 3 describes the use of fluorescein-N-hyroxysuccinimide ester to label IgG amino groups (3). Fluorescein isothiocyanate may also be used for the same purpose but it requires harsher conditions. The reaction is quenched by the addition of ethanolamine and excess labelling reagent is removed by gel filtration. 

Aminomethylcoumarin derivatives possess intense fluorescent properties within the blue region of the visible spectrum. Their emission range is sufficiently removed from other common fluorophores that they are excellent choices for double-labeling techniques. In fact, coumarin fluorescent probes are very good donors for excited-state energy transfer to fluoresceins. 

Sippel, T.O. (1981) New fluorochromes for thiols Maleimide and iodoacetamide derivatives of 3-phenyl-coumarin fluorophore./. Histochem. Cytochem. 29, 314. 

Blackburn C, Bai M, LeCompte KA et al (1994) Lithium responsive fluorophores derived from monoaza-12-crown-4 and coumarin. The influence of a methoxy side-arm on photophysical properties. Tetrahedron Lett 43 7915-7918... 

Relatively few probes have been widely applied to FlAs. Fluorescein and rho-damine, their derivatives, and to some extent phycoerythrin have dominated immunoassays that are based on steady-state measurements. Dansyl, umbelliferone, coumarins, and pyrenes are among others that have been used. Several more commonly used dyes are shown in Figure 14.2. Shorter-wavelength dyes tend to be less useful since they excite at wavelengths where endogenous chromophores, fluorophores, and... 

Somewhat unexpectedly, the 1-dansylamino derivative 193 (Scheme 58) of the 3-glucosidase inhibitor 2,5-dideoxy-2,5-imino-D-mannitol turned out a nanomolar inhibitor (K 2.4 nM) of Agrobacterium sp. (3-glucosidase.382 The same was true when the fluorophor and the inhibitor were separated by a C6 spacer arm. Equally active were the corresponding coumarin-3-carboxylic acid derivative 66 (Scheme 18 ... 

Various crown-ether-linked fluorophores have been described 1-14), The choice of the fluorophore and the way the crown is linked to the latter are of major importance. We have selected the following fluorophores a styryl derivative of benzoxazinone (BOZ-NMe2), a merocyanine (DCM, a well-known laser dye), and coumarin 153 (C153). 

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