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Studies were made on the position and dynamics of the OH-group of alpha-tocopherol in phospholipid membranes. There was no difference in the spin-lattice (T1) relaxation times at the 5a-position of alpha-tocopherol labeled with 13C- or C19F3-determined from the nuclear magnetic resonance (NMR) spectra of liposomes positively charged with stearylamine (SA) and negatively charged with dicetylphosphate (DCP). The zeta-potentials of egg yolk phosphatidylcholine (EYPC) liposomes with and without SA or DCP were not affected by incorporation of 20 mol% alpha-tocopherol, though incorporation of 10 mol% ascorbyl-palmitate decreased the zeta-potentials of EYPC and EYPC-SA liposomes. The P==O stretching band (1235 cm-1) of the phosphate group and C==O stretching band (1734 cm-1) of the acyl ester linkage in dimyristoylphosphatidylcholine (DMPC) liposomes, measured by Fourier transform-infrared (FT-IR) spectroscopy, were not changed by incorporation of alpha-tocopherol. These results suggest that no specific interaction occurred between the OH-group of alpha-tocopherol and the polar interfacial region of the bilayer. The dynamic quenching effects of n-(N-oxy-4,4'-dimethyloxazolidine-2-yl)stearic acids (n-NSs) on the intrinsic fluorescence of alpha-tocopherol were in the order 5-NS > 7-NS = 12-NS > 16-NS. Acrylamide, a water-soluble fluorescence quencher with a very low capacity to penetrate through phospholipid bilayers, had very low quenching efficiency. These results indicate that the bulk of the chromanol moiety of alpha-tocopherol is located in a position close to that occupied by the nitroxide group of 5-NS in the membranes and is poorly exposed at the membrane surface.(ABSTRACT TRUNCATED AT 250 WORDS)
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S Urano
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K Fukuzawa, and
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August 1980,
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K Fukuzawa, and
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K Fukuzawa, and
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A Shibata, and
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S Urano
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K Fukuzawa, and
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A Shibata, and
I Kumadaki, and
T Sakanaka, and
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November 2002,
Chemistry & biology,
K Fukuzawa, and
W Ikebata, and
A Shibata, and
I Kumadaki, and
T Sakanaka, and
S Urano
January 1978,
Biochimica et biophysica acta,
K Fukuzawa, and
W Ikebata, and
A Shibata, and
I Kumadaki, and
T Sakanaka, and
S Urano
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Mitochondrion,
K Fukuzawa, and
W Ikebata, and
A Shibata, and
I Kumadaki, and
T Sakanaka, and
S Urano
January 1989,
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