Zeaxanthin (dihydroxy-beta-carotene) but not beta-carotene rigidifies lipid membranes: a 1H-NMR study of carotenoid-egg phosphatidylcholine liposomes.
1H-NMR technique was applied to study liposomes formed with egg-yolk phosphatidylcholine containing as an additional component two carotenoid pigments: beta-carotene or zeaxanthin (dihydrohy-beta-carotene). A strong rigidifying effect of zeaxanthin but not of beta-carotene with respect to hydrophobic core of lipid bilayer was concluded from the carotenoid-dependent broadening of the NMR lines assigned to -CH2- groups and terminal -CH3 groups of lipid alkyl chains. A similar effect of zeaxanthin with respect to polar headgroups was concluded on the basis of the effect of the pigment on the shape of NMR lines attributed to -N+(CH3)3 groups. In contrast, beta-carotene increases motional freedom of lipid polar headgroups. The inclusion of both carotenoids to liposomes resulted in the enhanced penetration of Pr3+ ions to the polar zone of the external layer of a membrane monitored by the splitting of the -N+(CH3)3 signal, the effect of beta-carotene being much more pronounced. Differences in the effect on membrane structure and molecular dynamics observed for beta-carotene and its polar derivative are discussed in terms of organization of a carotenoid-containing lipid membrane.
Gabrielska
J
J
Department of Physics and Biophysics, Agricultural University, Wroclaw, Poland.
Gruszecki
W I
WI
D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D010713:Phosphatidylcholines / Q000378:metabolism; D011221:Praseodymium / Q000494:pharmacology; D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene / Q000031:analogs & derivatives* / Q000494:pharmacology*
D008051:Lipid Bilayers; D008081:Liposomes; D010713:Phosphatidylcholines; D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene; D011221:Praseodymium