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Studies on the Topography of Biomembranes: Regioselective Photolabelling in Vesicles with the Tandem Use of Cholesterol and a Photoactivable Transmembrane Phospholipidic Probe
Author(s) -
Nakatani Yoichi,
Yamamoto Masakuni,
Diyizou Yvonne,
Warnock William,
Dollé Valérie,
Hahn Wolfgang,
Milon Alain,
Ourisson Guy
Publication year - 1996
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.19960020204
Subject(s) - vesicle , transmembrane protein , bilayer , lipid bilayer , chemistry , phospholipid , membrane , side chain , cholesterol , crystallography , stereochemistry , biophysics , biochemistry , biology , organic chemistry , receptor , polymer
2 H NMR, DSC and UV studies of DMPC (1,2‐dimyristoyl‐ sn ‐glycero‐3‐phosphocholine) vesicles have demonstrated the favourable physicochemical properties of the transmembrane phospholipid probes 1 a and 1 b for membrane topographical studies. In particular, in the presence of a physiological amount of cholesterol, only one transmembrane conformation is observed. The use of 1 a and cholesterol together for photolabelling experiments in DMPC vesicles led to a remarkable improvement in the regioselectivity of cross‐linking between 1 a and DMPC, and between 1 a and cholesterol: the myristoyl chains functionalized at C11, C12 and C13 made up 95% of the total photolabelled myristates, and cholesterol was principally functionalized at the C25 position on the side‐chain. This indicates the formation of a highly ordered bilayer structure and proves directly the orientation of cholesterol perpendicular to the membrane plane with its chain terminal buried in the middle of the bilayer.