Quantitative Emission Spectroscopy in Media Where Appreciable Light Scattering Occurs

Kuntz, Eloise; Bishai, Fouad; Augenstein, Leroy

doi:10.1038/212980a0

Cited by 10 publications

(2 citation statements)

References 7 publications

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“…fluorescence observed for a dilute tryptophan solution is increased less than 5% by the addition of small unilamellar vesicles up to 2.5 mM or MLV up to 0.3-0.4 mM. [We note that in our experiments the detected fluorescence has a negligible contribution from Rayleigh, Tyndall, or Raman scattering, and therefore Figure 2 shows an authentic increase in measured fluorescence caused by light scattering (Kuntz et al, 1966).] Finally, in order to verify that at this lipid concentration scattering does not affect the measured fluorescence, tryptophan fluorescence was determined in buffer or in 0.3 mM lipid vesicles of egg PA/egg PC with 2 mM Cd2+ equilibrated by freeze-thaw-sonication.…”

Section: Resultsmentioning

confidence: 52%

Polypeptide clearing in model membranes: an analysis of the partition of gramicidin A' between cadmium ion induced gel and liquid-crystalline phases in vesicles of phosphatidic acid and phosphatidylcholine

Feigenson¹

1983

Biochemistry

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Using a simple model for a biological membrane we examine cation-induced gel phase formation and the depletion of polypeptide from the gel phase. The model system consists of vesicles of phosphatidic acid and phosphatidylcholine which contain gramicidin A'. By use of electron spin resonance to monitor lipid phase behavior, Cd2+ is found to induce gel and liquid-crystal phase coexistence over a wide range of lipid composition. Quenching of gramicidin A' tryptophanyl fluorescence by spin-labeled phosphatidic acid or spin-labeled phosphatidylcholine is analyzed to obtain the partition coefficient, Kp, for gramicidin A' between gel and liquid-crystal phases. The value of Kp = 3 favoring the liquid-crystal phase indicates a partial clearing of the membrane-bound polypeptide from Cd2+-induced gel phase regions of the membrane.

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Section: Resultsmentioning

confidence: 52%

Polypeptide clearing in model membranes: an analysis of the partition of gramicidin A' between cadmium ion induced gel and liquid-crystalline phases in vesicles of phosphatidic acid and phosphatidylcholine

Feigenson¹

1983

Biochemistry

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“…Look for a concentration that is well below where deviations from linearity are observed. Note that light scattering can lead to increased as well as decreased fluorescence signal [10].…”

Section: Correcting Fret Datamentioning

confidence: 99%

Fluorescence methods to detect phase boundaries in lipid bilayer mixtures

Heberle

Buboltz

Stringer

et al. 2005

Biochimica et Biophysica Acta (BBA) - Molecular Cell Research

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Phase diagrams of lipid mixtures can show several different regions of phase coexistence, which include liquid-disordered, liquid-ordered, and gel phases. Some phase regions are small, and some have sharp boundaries. The identity of the phases, their location in composition space, and the nature of the transitions between the phases are important for understanding the behavior of lipid mixtures. High fidelity phase boundary detection requires high compositional resolution, on the order of 2% compositional increments. Sample artifacts, especially the precipitation of crystals of anhydrous cholesterol, can occur at higher cholesterol concentrations unless precautions are taken. Fluorescence resonance energy transfer (FRET) can be used quantitatively to find the phase boundaries and even partition coefficients of the dyes between coexisting phases, but only if data are properly corrected for non-FRET contributions. Self-quenching of the dye fluorescence can be significant, distorting the data at dye concentrations that intuitively might be considered acceptable. Even more simple than FRET experiments, measurements of single-dye fluorescence can be used to find phase boundaries. Both FRET and single-dye fluorescence readily detect the formation of phase domains that are much smaller than the wavelength of light, i.e. "nanoscopic" domains.

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Tryptophan Phosphorescence from Proteins at Room Temperature

Vanderkooi

Topics in Fluorescence Spectroscopy

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Quantitative Emission Spectroscopy in Media Where Appreciable Light Scattering Occurs

Cited by 10 publications

References 7 publications

Polypeptide clearing in model membranes: an analysis of the partition of gramicidin A' between cadmium ion induced gel and liquid-crystalline phases in vesicles of phosphatidic acid and phosphatidylcholine

Polypeptide clearing in model membranes: an analysis of the partition of gramicidin A' between cadmium ion induced gel and liquid-crystalline phases in vesicles of phosphatidic acid and phosphatidylcholine

Fluorescence methods to detect phase boundaries in lipid bilayer mixtures

Tryptophan Phosphorescence from Proteins at Room Temperature

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