Masserini M, Palestini P, Freire E
Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218.
Biochemistry. 1989 Jun 13;28(12):5029-34. doi: 10.1021/bi00438a019.
The thermotropic behavior of dipalmitoylphosphatidylcholine large unilamellar vesicles containing gangliosides has been studied by high-sensitivity heating and cooling differential scanning calorimetry. These studies have been directed to identify and evaluate the influence of both the ganglioside lipidic portion and oligosaccharide moiety on the physical properties of phospholipid bilayers containing gangliosides. The influence of the ganglioside lipidic portion has been evaluated by studying the behavior of vesicles containing different GD1a molecular species carrying homogeneous lipid moieties (C20 or C18 sphingosine or sphinganine and stearic acid). The influence of the ganglioside saccharide portion was evaluated by investigating the thermotropic behavior of vesicles containing different gangliosides (GM1, Fuc-GM1, GD1a, GT1b) carrying the same homogeneous long-chain base moiety (C20 sphingosine and stearic acid). These studies, in conjunction with previous studies using homogeneous lipidic portion ganglioside GM1 and phosphatidylcholines of various chain lengths [Masserini, M., & Freire, E. (1986) Biochemistry 25, 1043-1049], indicate that, for a given oligosaccharide composition, gangliosides exhibit lateral phase separation in an extent dependent upon the length and unsaturation difference between the ganglioside long-chain base and phosphatidylcholine acyl chains. For a given ganglioside lipidic composition the extent of phase separation is dependent upon the number of sugar units present in the glycolipid. The addition of Ca2+ induces or enhances phase separation in a manner dependent on the long-chain base and oligosaccharide composition. Cooling differential scanning calorimetry experiments showed that the ganglioside property to form aggregates within the membrane is independent of the initial physical state of the bilayer.(ABSTRACT TRUNCATED AT 250 WORDS)
通过高灵敏度加热和冷却差示扫描量热法研究了含有神经节苷脂的二棕榈酰磷脂酰胆碱大单层囊泡的热致行为。这些研究旨在确定和评估神经节苷脂的脂质部分和寡糖部分对含有神经节苷脂的磷脂双层物理性质的影响。通过研究含有不同GD1a分子种类且带有均匀脂质部分（C20或C18鞘氨醇或鞘氨醇胺以及硬脂酸）的囊泡行为，评估了神经节苷脂脂质部分的影响。通过研究含有相同均匀长链碱基部分（C20鞘氨醇和硬脂酸）的不同神经节苷脂（GM1、Fuc-GM1、GD1a、GT1b）的囊泡热致行为，评估了神经节苷脂糖部分的影响。这些研究与之前使用均匀脂质部分的神经节苷脂GM1和各种链长的磷脂酰胆碱的研究[Masserini, M., & Freire, E. (1986) Biochemistry 25, 1043 - 1049]表明，对于给定的寡糖组成，神经节苷脂表现出横向相分离，其程度取决于神经节苷脂长链碱基与磷脂酰胆碱酰基链之间的长度和不饱和度差异。对于给定的神经节苷脂脂质组成，相分离程度取决于糖脂中存在的糖单元数量添加Ca2+以依赖于长链碱基和寡糖组成的方式诱导或增强相分离。冷却差示扫描量热法实验表明，神经节苷脂在膜内形成聚集体的性质与双层的初始物理状态无关。（摘要截断于250字）
