Harroun Thad A, Balai-Mood Kia, Hauß Thomas, Otomo Toshiya, Bradshaw Jeremy P
Preclinical Veterinary Sciences, R.(D.)S.V.S., University of Edinburgh, Summerhall, Edinburgh EH9 1QH UK ; National Research Council, Neutron Program for Materials Research, Chalk River Laboratories, Chalk River, Ontario K0J 1J0 Canada.
J Biol Phys. 2005 May;31(2):207-18. doi: 10.1007/s10867-005-2097-0.
As part of a study of the molecular basis of membrane fusion by enveloped viruses, we have used neutron diffraction to study the lamellar (L(α)) to inverse hexagonal (H(II)) phase transition in the phospholipid N-methylated dioleoylphosphatidylethanolamine. This lipid was chosen because its phase transitions are particularly sensitive to the presence of agents that have been demonstrated to promote or inhibit membrane fusion. Two different geometries of neutron diffraction were used: small angle scattering (SANS) and a membrane diffractometer. The SANS measurements were carried out on the SWAN instrument at KEK, Japan, using dispersions of multilamellar vesicles (MLVs). The diffractometer measurements used the V1 instrument at BeNSC-HMI, Germany, with a specially-constructed cell that holds a stack of lipid bilayers in an excess-water state. The two approaches are compared and discussed. Although the diffractometer takes considerably longer to collect the data, it records much higher resolution than the SANS instrument. The samples recorded in the excess-water cell were shown to be well aligned, despite the lipids being fully hydrated, allowing for the production of high-resolution data. Trial measurements performed have demonstrated that sample alignment is preserved throughout the L(α) to H(II) phase transition, thereby opening up possibilities for obtaining high-resolution data from non-lamellar phases.
作为对包膜病毒膜融合分子基础研究的一部分,我们利用中子衍射研究了磷脂N-甲基化二油酰磷脂酰乙醇胺从层状(L(α))到反六角形(H(II))相的转变。选择这种脂质是因为其相变对已被证明能促进或抑制膜融合的物质的存在特别敏感。使用了两种不同几何结构的中子衍射:小角散射(SANS)和膜衍射仪。SANS测量是在日本KEK的SWAN仪器上进行的,使用的是多层囊泡(MLV)分散体。衍射仪测量使用的是德国BeNSC-HMI的V1仪器,配有一个特殊构造的样品池,该样品池能使脂质双层堆叠处于过量水状态。对这两种方法进行了比较和讨论。尽管使用衍射仪收集数据所需的时间长得多,但它记录的分辨率比SANS仪器高得多。结果表明,尽管脂质完全水合,但在过量水样品池中记录的样品排列良好,从而能够产生高分辨率数据。进行的试验测量表明,在从L(α)到H(II)的相变过程中样品排列得以保持,从而为从非层状相获得高分辨率数据开辟了可能性。