Fluorescein resonance energy transfer

Like FRET, today BRET is predominantly used in biological sciences, especially in the monitoring of protein-protein interactions such as hormone-receptor interaction [223, 224] and protein-DNA interaction in living systems. However, BL resonance energy transfer can also be applied in immunoassays by using for instance a peptide-tagged luciferase and a fluorescein-labeled antipeptide antibody [225]. The development of more BRET assays for small-molecule analytes is thus awaited. 

Liu B, Bazan GC (2007) Tetrahydrofuran activates fluorescence resonant energy transfer from a cationic conjugated polyelectrolyte to fluorescein-labeled DNA in aqueous media. Chem Asian J 2 499-504... 

Fluorescence resonance energy transfer has also been used for ionic strength measurements.(95) Fluorescein labeled dextran (donor) and polyethyleneimine-Texas Red (acceptor) were placed behind a dialysis membrane. The polymer association is ionic strength dependent and the ratio of intensities (F o/Fw) was used as the measured parameter. Since both the donor and acceptor are fluorescent, this kind of sensor may allow expand the sensitive ionic strength range by shifts in observation wavelength, as was discussed for pH probe Carboxy SNAFL-2 (see Section 10.3). 

Fluorescein isothiocyanate (FITC), 412 Fluorescence resonance energy transfer (FRET), 348, 377 Fluorescent labeling, 323 Flux method, 440 Formaldehyde, 403... 

Fluorescence resonance energy transfer (FRET) is a technique that has been used to measure distances between pairs of proximal fluorochromes. A suitable pair consists of a donor fluorochrome, which has an emission spectrum that significantly overlaps with the absorption spectrum of an acceptor fluorochrome (2). With the availability of monoclonal antibodies to many cell-surface determinants, intramolecular distances between nearby epitopes and intermolecular distances between adjacent cell-surface macromolecules can be investigated to analyze molecular interactions influencing important cellular events. Such monoclonal antibodies can be conjugated to fluorescein-isothiocyanate (FITC) as the donor, and either tetramethyl-rhodamine-isothiocyanate (TRITC) or phycoerythrin (PE) as the acceptor. 

A FRET-based reporter gene assay that is now commercially available from Panvera was described by Zlokarneik and co-workers [109]. The assay uses a membrane-permeable substrate (CCE2, a coumarin-fluorescein derivative) for the reporter protein j3-lactamase. By hydrolyzing the substrate, the enzyme disrupts the intramolecular resonance energy transfer between the coumarin and the fluorescein, which changes the fluorescence emission from green at 520 run to blue at... 

By covalent attachment of fluorescein (as donor) and rhodamine (as acceptor) to the 5 -termini of complementary oligodeoxyribonucleotides, hybridization can be measured by non-radiative fluorescence resonance energy transfer (FRET) from fluorescein to rhodamine as hybridization occurs, the emission intensity of fluorescein falls while that of rhodamine rises." 9 Correction must be made for... 

Figure 2. Schematic depiction of fluorescent resonance energy transfer (FRET) between the subunits of cAMP-dependent protein kinase (55) used for detecting cAMP. In the absence of cAMP, most of the kinase is in the holoenzyme state, which facilitates FRET between the fluorescein-labelled catalytic (C) subunits and the ihodamine-labelled regulatory (R) subunits. Excitation of fluorescein gives substantial re-emission from rhodamine at the expense of fluorescein. In the presence of high concentrations of cAMP, the R subunits undergo conformational change that dissociates them from the C Subunits and prevents FRET. Therefore, excitation of fluorescein results in fluorescein emission rather than rhodamine reemission (Reproduced with permission from ref. 55. Copyright 1991 Macmillan Maga2dnes).

Glucose Fluorescein and rhodamine Resonance energy transfer 219... 

A fluorescein boronic acid derivative was prepared to function as the fluorescent partner and a series of methyl-red-inspired diols were synthesized as qnencher partners to probe the FOrster resonance energy transfer (FRET) quenching sensing regime based on boronate ester formation (Fignre 11). ... 

---