Phase behavior in multilamellar vesicles of DPPC containing ganglioside GM3 with a C18:1 sphingoid base and a 24:0 acyl chain (GM3(18,24)) observed by X-ray diffraction.
Structures and phase behavior of multilamellar vesicles of 1,2-dipalmitoyl-L-phosphatidylcholine (DPPC) containing various amount of ganglioside GM3 with a C18:1 sphingoid base and a 24:0 acyl chain (GM3(18,24)) were investigated by small-angle X-ray diffraction. Below 3.5 mol% GM3 content, the phase behavior was similar to that of pure DPPC except for a slight increase of lamellar repeat distance in the L(beta'), the P(beta') and the L(alpha) phases and a decrease of the pretransition temperature. In the range of 4-12 mol% GM3 content, another phase which has larger repeat distances coexisted with the phase observed below 3.5 mol% GM3 content. This has been interpreted that the phase separation into GM3-poor phase (denoted as A-phase) and GM3-rich phase (denoted as B-phase) took place. Above 13 mol% GM3 content, the B-phase became dominant. This phase separation may be related to the formation of GM3-enriched microdomains that had been observed on the cell surfaces which express large amounts of GM3, such as murine B16 melanoma (J. Biol. Chem. 260 (1985) 13328).
Matuoka
Sinzi
S
Department of Physics, School of Medicine, Sapporo Medical University, S 1 W 17, Chuo-ku, Sapporo, Hokkaido 060-8556, Japan. matuoka@sapmed.ac.jp
Akiyama
Morio
M
Yamada
Hirokuni
H
Tsuchihashi
Keiko
K
Gasa
Shinsei
S
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry*; D000215:Acylation; D005679:G(M3) Ganglioside / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D046911:Macromolecular Substances; D008560:Membrane Fluidity; D021962:Membrane Microdomains / Q000737:chemistry*; D008968:Molecular Conformation; D013696:Temperature; D014961:X-Ray Diffraction / Q000379:methods*
D005679:G(M3) Ganglioside; D008051:Lipid Bilayers; D008081:Liposomes; D046911:Macromolecular Substances; D015060:1,2-Dipalmitoylphosphatidylcholine