Fluorescence polarization anisotropy measurement

Thomas, J. C., Allison, S. A., Appellof, C. J., and Schurr, J. M. (1980). Torsion dynamics and depolarization of fluorescence of linear macromolecules. II. Fluorescence polarization anisotropy measurements of a clean viral phi 29 DNA. Biophys. Chem. 12, 177-188. 

Fluorescence polarization (anisotropy) version 2 (IMAP) Fluorophore labeled peptides bind to special detection beads coated with trivalent metal binding results in change in Brownian motion measured as with FP1 above Versatile without need for antibody Susceptible to compound interference peptide must be relatively small precludes use of protein substrates Turek-Etienne (2003a)... 

Aptamers have a strong potential for multiplex sensing of proteins. Thus, a chip-based biosensor was developed for specific detection and quantification of cancer-associated proteins in complex biological mixtures using immobilized fluorescently labeled DNA and RNA aptamers. Fluorescence polarization anisotropy was used for solid- and solution-phase measurements of target protein binding [51]. 

Fluorescence polarization (FP) measurements provide information on molecular orientation and mobility and processes that modulate them, including receptor-ligand interactions, protein-DNA interactions, proteolysis, membrane fluidity, and muscle contraction. The degree of polarization is determined from measurements of fluorescence intensities parallel and perpendicular with respect to the plane of linearly polarized excitation light, and is expressed in terms of fluorescence polarization (P) or anisotropy (r). Therefore, the FP experiment is less... 

The viscosities of the fats and oils in the temperature range chosen can be determined by steady-state fluorescence polarization by measuring the anisotropy... 

The fluorescence depolarization technique excites a fluorescent dye by linearly polarized light and measures the polarization anisotropy of the fluorescence emission. The fluorescence anisotropy, r, is defined as... 

Situation with H-bonding also demands to take into account the fact that alcohols have ability to form various associates or even clusters at normal conditions. The most efficient method for determination of inhomogeneity in the excited states is fluorescence polarization measurements. These methods also frequently applied for studying of solvent viscosity, they may be provided in two variants steady state and time-resolved. Relations for time-resolved and steady state fluorescence anisotropy may be given as [1, 2, 75] ... 

The versatility of luminescence goes beyond intensity-, wavelength- and kinetic-based measurements. Fluorescence polarization (or anisotropy) is an additional parameter still largely unexplored for optical sensing yet widely used in Biochemistry to study the interaction of proteins, the microfluidity of cell membranes and in fluorescence immunoassays. Although only a few optosensors based on luminescence polarization measurements can be found in the literature, elegant devices have recently been reported to measure chemical parameters such as pFI or O2 even with the bare eye41. 

Dr can be determined by time-resolved fluorescence polarization measurements, either by pulse fluorometry from the recorded decays of the polarized components I l and 11, or by phase fluorometry from the variations in the phase shift between J and I as a function of frequency (see Chapter 6). If the excited-state lifetime is unique and determined separately, steady-state anisotropy measurements allow us to determine Dr from the following equation, which results from Eqs (5.10) and (5.41) ... 

In Chapter 5, devoted to fluorescence polarization, it was shown that information on the rotational motions of a fluorophore can be obtained from emission anisotropy measurements. Application to the evaluation of the fluidity of a medium, or molecular mobility, is presented below. 

Fluorescence polarization is the subject of Chapter 5. Factors affecting the polarization of fluorescence are described and it is shown how the measurement of emission anisotropy can provide information on fluidity and order parameters. 

The results of fluorescence polarization studies of proteins were discussed above. Time-resolved anisotropy measurements often permit, without any additional variation of experimental conditions, intramolecular rotations to be distinguished from rotation of the whole protein molecule and characterized,... 

This problem does not exist with time-dependent fluorescence polarization measurements where the decay of the emission anisotropy r(t) is obtained by determining the decay of Iz and Ix according to eq 12. 

Steady-state fluorescence polarization studies have been carried out with a number of peptides, including model peptides, ACTH, glucagon, melittin, and thyrocalcitonin. This work has been reviewed 5 and will not be discussed in the present article. More recently, interesting information on the rotational behavior and structural flexibility of various peptides has been obtained from fluorescence anisotropy decay measurements. 

Time-resolved fluorescence polarization measurements for 1 and 2 in n-heptane showed that after pulsed excitation, the initial value of the fluorescence anisotropy is about 0.25. This... 

For quite some time, there have been indications for a phase-separation in the shell of polyelectrolyte block copolymer micelles. Electrophoretic mobility measurements on PS-PMAc [50] indicated that a part of the shell exhibits a considerable higher ionic strength than the surrounding medium. This had been corroborated by fluorescence studies on PS-PMAc [51-53] and PS-P2VP-heteroarm star polymers [54]. According to the steady-state fluorescence and anisotropy decays of fluorophores attached to the ends of the PMAc-blocks, a certain fraction of the fluorophores (probably those on the blocks that were folded back to the core/shell interface) monitored a lower polarity of the environment. Their mobility was substantially restricted. It thus seemed as if the polyelectrolyte corona was phase separated into a dense interior part and a dilute outer part. Further experimental evidence for the existence of a dense interior corona domain has been found in an NMR/SANS-study on poly(methylmethacrylate-fr-acrylic acid) (PMMA-PAAc) micelles [55]. 

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