S. Mazeres et al., Probing the lateral organization of membranes: fluorescence repercussions of pyrene probe distribution, SPECT ACT A, 57(11), 2001, pp. 2297-2311
Citations number
41
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences
Journal title
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
Phospholipids pyrene labeled are widely used to investigate dynamics and or
ganizations of membranes. We studied pyrene probe lateral distribution by a
nalyzing the variations of the molar absorption coefficient (epsilon) versu
s probe concentrations,, in small unilamellar vesicles (SUV) made of phosph
olipids and/or glycolipids, with pyrene labeled phosphatidylcholine (PyPC)
or phosphatidylglycerol (PyPG). The results were interpreted according to a
n infinite associative model. They indicated that an effective self-associa
tion process corresponding to K ranging from 30 to 100 M-1 occurred with th
ose probes incorporated in dimannosyl diacylglycerol (DMDG). In contrast, a
fter SUV labeling of egg yolk phosphatidylcholine (EggPC) or phosphatidylgl
ycerol (EggPG), K values < 1 M-1 were determined. The corresponding percent
ages of various stacked forms of pyrene probes were calculated. They indica
ted that, for a 3% PyPG labeling, the monomer represented 21% of n-mers in
DMDG and 94% in EggPC. The analysis of fluorescence experiments carried out
on the same samples indicated that: (i) the fluorescence process of pyrene
probes was generated by the monomers; and (ii) the excimer forming resulte
d from a diffusional encounter between one excited and one non-excited mono
mer. A correction of fluorescence data allowing a more correct interpretati
on of fluorescence measurements was proposed. (C) 2001 Elsevier Science BN.
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