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Proceedings Paper

Fluorescence Quenching And Multiple-Frequency Phase Fluorometry In Peptide-Lipid Micelles
Author(s): Larry R McLean; Karen A Hagaman; Thomas J Owen; D.Jean Sprinkle; John L Krstenansky; Maurice R Eftink
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Paper Abstract

The conformation and environment of the single tryptophan residue of a model amphipathic helical peptide (MAP) in mixed micelles with dimyristoylphosphatidylcholine (DMPC) at different molar ratios was examined by circular dichroism (CD) and fluorescence spectroscopy. The peptide was synthesized by solid-phase techniques and micelles were formed by incubation. The radius of the disk-shaped micelles (measured by electron microscopy) decreases with increasing concentrations of MAP within the micelles. The alpha-helix content (measured by CD) of MAP increases and the fluorescence spectrum shifts to shorter wavelengths with larger diameter micelles. In acrylamide quenching experiments, the rate decreases and the activation energy increases with increasing micelle diameter. Multiple-frequency phase fluorometry data are consistent with either two environments or a Lorentzian distribution of a single environment for the tryptophan residue in the mixed micelles. The distribution depends upon the size of the micelle. With increasing micelle diameter, the relative fraction of the longer lifetime component or the width of the lifetime distribution is increased. These data suggest that the tryptophan residue environment within the model peptide-lipid micelle varies as a function of micellar size. A model for the lipid-peptide interaction in which the conformation of the peptide depends upon the degree of curvature at the edge of the micelle will be presented..

Paper Details

Date Published: 24 June 1988
PDF: 5 pages
Proc. SPIE 0909, Time-Resolved Laser Spectroscopy in Biochemistry, (24 June 1988); doi: 10.1117/12.945425
Show Author Affiliations
Larry R McLean, Merrell Dow Research Institute (United States)
Karen A Hagaman, Merrell Dow Research Institute (United States)
Thomas J Owen, Merrell Dow Research Institute (United States)
D.Jean Sprinkle, Merrell Dow Research Institute (United States)
John L Krstenansky, Merrell Dow Research Institute (United States)
Maurice R Eftink, University of Mississippi (United States)

Published in SPIE Proceedings Vol. 0909:
Time-Resolved Laser Spectroscopy in Biochemistry
Joseph R. Lakowicz, Editor(s)

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