A SANS STUDY OF HIGH-PRESSURE PHASE-TRANSITIONS IN MODEL BIOMEMBRANES
A SANS STUDY OF HIGH-PRESSURE PHASE-TRANSITIONS IN MODEL BIOMEMBRANES
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DOI：
10.1002/bbpc.19890930611
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发表时间：
1989-06-01
期刊：
影响因子：
--
通讯作者：
PILGRIM, WC
中科院分区：
文献类型：
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作者：
WINTER, R;PILGRIM, WC
通过小角中子散射（SANS）研究了由不同烃链长度和不饱和度组成的不同模型生物膜（DPPC、DMPC、DEPC和POPC*）的相行为和向热和正压相变，它们分别是高达约65 ℃和3 kbar的温度和压力的函数。在整个温度范围内，观察到从液晶到凝胶态的压力诱导结构相变。该转变的压力随着温度的升高而增加，斜率dTm/dP为约21 ℃/kbar，这对于所有研究的不同脂质是共同的。SANS实验表明，DEPC中的两个反式双键和POPC中sn-2烃链上的顺式双键的作用，不仅在液晶态，而且在凝胶态，都增强了烃链的构象无序。对于DEPC和POPC，凝胶状态下的优选结构构象可能不像饱和磷脂DMPC和DPPC的凝胶状态那样倾斜。仅对于DPPC多层囊泡，已观察到在较高压力下的额外凝胶相，这可归因于脂质双层系统中相对链的烃链的叉指状化。
The phase behaviour and thermotropic and barotropic phase transitions of different model biomembranes (DPPC, DMPC, DEPC and POPC*), which consist of different hydrocarbon chain length and degree of unsaturation, have been investigated by small-angle neutron scattering (SANS) as a function of temperature and pressure up to about 65.degree.C and 3 kbar, respectively. A pressure induced structural phase transition from a liquid-crystalline to a gel state is observed for the whole temperature range studied. The pressure of this transition increases with increasing temperature with a slope dTm/dP of about 21.degree.C/kbar, which is common for all the different lipids investigated. The SANS experiments indicate that the effect of the two trans double bonds in DEPC and the cis double bond in the sn-2 hydrocarbon chain of POPC enhances the conformational disorder in the hydrocarbon chains not only in the liquid-crystalline, but also in the gel state. For DEPC and POPC the prefered structural conformation in the gel state is probably not tilted as it is in the gel state of the saturated phospholipids DMPC and DPPC. Only for DPPC multilamellar vesicles, an additional gel phase at higher pressures has been observed, which can be ascribed to an interdigititation of the hydrocarbon chain of opposing chains in the lipid bilayer system.