Dehydration-induced lamellar-to-hexagonal-II phase transitions in DOPE/DOPC mixtures.
Dehydration-induced lamellar-to-hexagonal-II phase transitions in DOPE/DOPC mixtures.
复制标题
DOPE/DOPC 混合物中脱水诱导的层状至六方-II 相变。
DOI：
10.1016/0005-2736(93)90385-d
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Steponkus,PL
中科院分区：
文献类型：
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作者：
Webb,MS;Hui,SW;Steponkus,PL
从非驯化黑麦植物分离的原生质体的质膜在-10 ° C冷冻诱导脱水期间经历从双层到倒六边形（HII）相的转变。有人建议（Bryant，G.和Wolfe，J.（1989）Eur. Biophys. J. 16，369-372），各种膜组分的差异水合可引起高度水合的（例如，PC）在脱水过程中从水化不良（PE）组分中分离。这可以产生更倾向于形成III相的PE富集结构域。我们用冷冻断裂电子显微镜、差示扫描量热法和X射线衍射法研究了DOPE和DOPC混合物在20°C下的溶致相行为。较高的DOPE含量和较低的水含量有利于III相的形成。当DOPE/DOPC的体积比为1：1和1：3时，当水含量略高于HII相时，出现两个Lα相。层状结构重复间距的水化依赖性表明，DOPE富集区优先发生Lα-→ H II-相变。3：1的DOPE/DOPC混合物在脱水过程中没有分离成两个Lα相。这些数据表明，不同的膜组件的差异水合特性可能会导致其横向流体-流体分层脱水过程中。
Plasma membranes of protoplasts isolated from non-acclimated rye plants undergo a transition from the bilayer to the inverted hexagonal (HII) phase during freeze-induced dehydration at –10°C. It has been suggested (Bryant, G. and Wolfe, J. (1989) Eur. Biophys. J. 16, 369–372) that the differential hydration of various membrane components may induce fluid-fluid demixing of highly hydrated (e.g., PC) from poorly hydrated (PE) components during dehydration. This could yield a PE-enriched domain more prone to form the HIIphase. We have examined the lyotropic phase behavior of mixtures of DOPE and DOPC at 20°C by freeze-fracture electron microscopy, differential scanning calorimetry, and X-ray diffraction. HIIphase formation was favored by higher proportions of DOPE and lower water contents. Mixtures of 1:1 and 1:3 DOPE/DOPC had a hydration-dependent appearance of two Lαphases at water contents just above those at which the HIIphase occured. The hydration-dependence of the lamellar repeat spacings suggested that the DOPE-enriched domains preferentially underwent the Lα-to-HIIphase transition. Mixtures of 3:1 DOPE/DOPC did not separate into two Lαphases during dehydration. These data suggest that the differential hydration characteristics of various membrane components may induce their lateral fluid-fluid demixing during dehydration.