Microprocessor-controlled photon-counting spectrofluorometer

Gratton, Enrico; Limkeman, Mark

doi:10.1063/1.1137386

Cited by 15 publications

(4 citation statements)

References 8 publications

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“…Steady-state spectrofluorometric experiments were carried out with the microprocessor-controlled photon-counting apparatus described by Gratton and Limkeman (1983). Lifetime measurements were performed on the multifrequency phase and modulation fluorometer described by Gratton and Limkeman (1984) equipped with an ISSIADC interface (ISS, Champaign, Illinois) for data acquisition and analysis.…”

Section: Resultsmentioning

confidence: 99%

The fluorescence properties of a DNA probe

Barcellona

Gratton

1990

Eur Biophys J

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Steady-state and dynamic fluorescence measurements have been performed on DAPI in solution and in complexes formed with a number of synthetic and natural polydeoxynucleotides. The decay of DAPI in buffer at pH 7 was decomposed using two exponentials having lifetime values of approximately 2.8 ns and 0.2 ns. The double exponential character of the decay was maintained over a large pH range from 3 to 9. At pH 1 the short component dominated, whereas at pH 12, only the long component was detectable. Two distinct spectra were associated with the two lifetime components; the short component was shifted to the red. The short lifetime component occurs in the presence of water. In water the excitation spectra depended on the emission wavelength and there was no viscosity dependence of the two forms. To explain these results we propose that there is a ground state conformer in which preferential solvation of the indole ring allows proton transfer in the excited state. DAPI complexed with polydeoxynucleotides retained most of the features of the decay of DAPI in solution. However, the complexes with fully AT-containing polymers stabilized the longer lifetime form of DAPI because the stronger binding enhanced solvent shielding. A gradual increase of the short lifetime component, which monitors dye solvent exposure, was obtained as the AT content was decreased. For polyd(GC) the decay was similar to that of free DAPI.

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Section: Resultsmentioning

confidence: 99%

The fluorescence properties of a DNA probe

Barcellona

Gratton

1990

Eur Biophys J

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“…Fluorescence Measurements. Fluorescence lifetime and differential polarization measurements were performed with a multifrequency phase fluorometer (Gratton & Limkeman, 1983) equipped with a ISS-ADC interface for data collection. The wavelength of excitation was 325 nm with a heliumcadmium laser as the light source.…”

Section: Methodsmentioning

confidence: 99%

Orientational distribution of 1,6-diphenyl-1,3,5-hexatriene in phospholipid vesicles as determined by global analysis of frequency domain fluorimetry data

Wang¹,

Beechem²,

Gratton³

et al. 1991

Biochemistry

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Polarized differential phase and modulation ratios were obtained for 1,6-diphenyl-1,3,5-hexatriene (DPH) in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) vesicles by using multifrequency phase fluorometry. Data were analyzed in terms of both empirical sums-of-exponentials modeling and directly in terms of the orientational distribution functions. The orientational analysis model was used to recover the angular distribution of DPH and the rotational diffusion coefficient in the various membrane model systems throughout the phase transition. A global analysis methodology was utilized to obtain an internally consistent set of parameters that fit all of the data simultaneously. The rank order parameters (P2) and (P4) were extracted from the experimental data, and the angular distribution functions of DPH were calculated. When the time-zero anisotropy (r0) of several sets of data taken at various temperatures were linked in a single global analysis, better recovery of the fourth rank order parameter (P4), diffusion constant D, and r0 was obtained with respect to the unlinked analysis. From these recovered values, a detailed picture concerning the orientational distribution of DPH in membranes as a function of temperature was obtained. The results suggest that a single population of DPH molecules was present in the bilayers with their orientational distributions dependent upon the physical state of the membranes in the pure phases. During the phase transition, a superposition of two populations corresponding to the population of the pure phases was present. As the temperature increased in the transition region, one population was increasing at the expense of the other.

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“…Steady-state fluorescence spectra were recorded by using the photon counting spectrofluorometer constructed by Gratton and Limkeman (1983). The myoglobin fluorescence spectra were not corrected for the Raman contribution since the protein fluorescence is almost comparable to the Raman intensity because of the energy transfer from tryptophan to the heme.…”

Section: Methodsmentioning

confidence: 99%

Multiple conformational states in myoglobin revealed by frequency domain fluorometry

Bismuto

Irace²,

Gratton³

1989

Biochemistry

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The tryptophanyl fluorescence decays of two myoglobins, i.e., sperm whale and tuna myoglobin, have been examined in the frequency domain with an apparatus which utilizes the harmonic content of a mode-locked laser. Data analysis was performed in terms of continuous distribution of lifetime having a Lorentzian shape. Data relative to sperm whale myoglobin, which possesses two tryptophanyl residues, i.e.,

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Microprocessor-controlled photon-counting spectrofluorometer

Cited by 15 publications

References 8 publications

The fluorescence properties of a DNA probe

The fluorescence properties of a DNA probe

Orientational distribution of 1,6-diphenyl-1,3,5-hexatriene in phospholipid vesicles as determined by global analysis of frequency domain fluorimetry data

Multiple conformational states in myoglobin revealed by frequency domain fluorometry

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