Fluorescence, depolarization quenching

J. R. Lakowicz and B. Maliwal, Oxygen quenching and fluorescence depolarization of tyrosine residues in proteins, J. Biol. Chem. 258, 4794-4801 (1983). 

Other MW enhancers have been described. Peptides with oligonucleotides as enhancers were attached to substrates for a polarization assay with caspase-3 (Lopez-Calle et al., 2002). As strepta-vidin has four binding sites, fluorescence self-quenching effects between the dye molecules can occur with increasing binding degree resulting in depolarization (Pope et al., 1999). The alternative MW enhancer approaches may overcome this limitation. 

A brief review and reassessment of data on the photophysics of benzene has been presented by Pereira. Evidence for the l E2g valence state has been obtained by u.v. two-photon spectroscopy.Slow electron impact excites fluorescence in thin films of benzene at 77 K as well as emission from isomers." The fluorescence yields and quenching by chloroform of alkyl-benzenes and 1-methylnaphthalene after excitation into Si, Sz, and S3 states and after photoionization have been measured. The channel-three process has been reconsidered in terms of the effects of local modes and Morse oscillator potentials. Excited-state dipole moments of some monosubstituted benzenes have been estimated from solvent effects on electronic absorption spectra, Structural imperfections influence the photochemistry of durene in crystals at low temperatures. Relaxation time studies on excited oxido-substituted p-oligophenylenes have been made by fluorescence depolarization... 

Various spectroscopic techniques and probes have been used to investigate solubilization of probe molecules, mostly using UV/visible spectroscopy, fluorescence spectroscopy, ESR spectroscopy [64, 74, 217, 287] and NMR-spectro-scopy [367-369]. Fluorescence spectroscopy is particularly versatile [370], as various static and dynamic aspects can be covered by studying excitation and emission spectra, excimer or exciplex formation, quantum yields, quenching, fluorescence life-times, fluorescence depolarization, energy transfer etc. 

Singlet state emission (10 — 10 s) fluorescence quenching excimer emission exciplex emission photodimerization fluorescence depolarization... 

Lakowicz and Maliwal, 1983, Oxygen quenching and fluorescence depolarization of tyrosine residues in proteins. Journal of Biological Chemistry 258,4794-4801. Lakowicz, J. R., Maliwal, B., Cherek, H. and Balter, A. 1983, Rotational freedom of tryptophan residues in proteins and peptides. Biochemistry. 22, 1741 - 1752. 

To perform structural research on a food stuff into which a colorant is incorporated, special properties of fluorescing molecules are exploited fluorescence efficiency, fluorescence lifetime, fluorescence quenching, radiationless energy (Foerster) transfer, stationary or time-dependent fluorescence polarization and depolarization." Generally, if food colorants fluoresce, they allow very sensitive investigations which in most cases cannot be surpassed by other methods. 

The various methods for the measurement of t/, the actual lifetime, can be classified as steady state and nonsteady state methods. In the steady state methods are included lifetime determinations from fluorescence quenching data and depolarization studies, the theoretical aspect of which have already been discussed in Sections 6.4 and 4.10, respectively. 

The dynamics of intramolecular quenching of pyrenyl fluorescence and intramolecular excimer formation have been used to investigate liquid-crystalline solvents. Ruorescence depolarization has also been used to... 

Fredrickson3 has formulated expressions for the concentration depolarization of fluorescence in the presence of molecular rotation. A theoretical examination of diffusion influenced fluorescence quenching by nearest possible quenching neighbours in liquids has been made35. A modified version of Smoluchowski - Collins - Kimball formulation of the Stern - Volmer equations has been matched with experimental data for quenching of anthraquinone derivatives by N,N-dimethyl- -toluidine. Another paper discusses this work on the basis of the kinetics of partly diffusion controlled reactions3 . 

Historically, hydrogen exchange experiments (i.e., the replacement of one isotope of hydrogen bound to an O, N, or S atom in the protein interior by another isotope from the solvent water) provided some of the earliest evidence for the existence of conformational fluctuations in proteins. More recently, a wide range of experimental methods (such as fluorescence quenching and depolarization, nuclear magnetic resonance relaxation, infrared and Raman spectroscopy, and X-ray and inelastic neutron scattering) have been used to study the motions in proteins. However, it is primarily the application of theoretical methods, particularly molecular dynamics simulations, that have... 

---