Chelation-enhanced fluorescence

CHEF was originally exploited for the detection and quantification of metal ions, such as those developed for the detection and quantification of Ca [10]. Given 

The8-hydroxyquinolinechromophore manifests weakfluorescence in the absence of metal ions in aqueous solution. However, in the presence of various metal ions (e.g., Zn + and 8-hydroxyquinoline becomes strongly fluorescent 

Altering the flanking amino acids provides a means to fine-tune the binding affinity for and thus the capacity to detect the divalent ion at different target concentrations. 

Although this strategy was originally employed for the detection of Zn , it was quickly realized that there would potentially be greater impact in the application of the quinolone fluorophore and CHEF for detecting kinase activity, as the 

An essential feature of Sox-containing sensors is the differential binding affinity for Mg between the substrate and product (phosphorylated) peptides. A 10-to 25-fold enhancement of binding affinity for Mg (as measured by dissociation constant, /Cp) is observed upon phosphorylation. Therefore, substrate peptides manifest low background fluorescence, while phosphorylation results in robust fluorescence increases (three- to eightfold) in the presence of Mg . In the presence of Mg and ATP, these sensors accurately report kinase activity, while providing kinetic detail. The kinetic parameters (/C, and sensors are 

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Huston ME, Haider KW, Czamik AW (1988) Chelation-enhanced fluorescence in 9,10-bis (TMEDA)anthracene. J Am Chem Soc 110 4460 1462... 

Akkaya EU, Huston ME, Czamik AW (1990) Chelation-enhanced fluorescence of anthryla-zamacrocycle conjugate probes in aqueous-solution. J Am Chem Soc 112 3590-3593... 

Vance DH, Czamik AW (1994) Real-time assay of inorganic pyrophosphatase using a high-affinity chelation-enhanced fluorescence chemosensor. J Am Chem Soc 116 9397-9398... 

E. U. Akkaya, M. E. Huston, and A. W. Czarnik, Chelation-enhanced fluorescence of anthry-lazamacrocycle conjugate probes in aqueous solution,./. Am. Chem. Soc. 112, 3590-3593 (1990). 

Chelation-Enhanced Fluorescence of Anthlylazamacrocycle Chemosensors in Aqueous Solution... 

Chelation-Enhanced Fluorescence Detection of Nonmetal Ions... 

The methylene-blue sensitized photo-oxidation of mesodiphenyl-helianthrene has been proposed as a convenient new chemical actinometer for the extended wavelength range 610-670 nm. Chelation enhanced fluorescence can be used to detect non-metal ions such as carboxylate, sulphate, and phosphate groups. Anthrylpolyamines can be employed as effective probes for this purpose. 

Real-Time and Continuous Sensors of Protein Kinase Activity Utilizing Chelation-Enhanced Fluorescence... 

Figure 1.1 Environment-sensitive fluorescence, (a) Fluorescence emission spectrum of the environment-sensitive fluorophore, 4-DMN, in solvents of various polarities and (b) structure of the Sox fluorophore demonstrating chelation-enhanced fluorescence.

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