Coexistence of two liquid crystalline phases in dihydrosphingomyelin and dioleoylphosphatidylcholine binary mixtures
Coexistence of two liquid crystalline phases in dihydrosphingomyelin and dioleoylphosphatidylcholine binary mixtures
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DOI：
10.1016/j.bbamem.2014.01.017
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发表时间：
2014-05-01
影响因子：
3.4
通讯作者：
Murata, Michio
中科院分区：
文献类型：
--
作者：
Kinoshita, Masanao;Matsumori, Nobuaki;Murata, Michio
最近，DHSM作为天然存在的SM中的一个次要成分，被证明比天然存在的SM更有效地形成筏状有序相，因为DHSM具有更大的诱导分子间氢键的潜力。为了研究dhsm诱导的氢键对模相偏析的影响，采用量热法和荧光观察方法研究了硬脂酰dhsm /DOPC二元双分子层的热相行为，并与SSM/DOPC二元双分子层进行了比较。结果表明，DHSM/DOPC双分子层在有限的组成范围内发生了两个La相之间的相偏析。另一方面，在SSM/DOPC混合物的主转变温度以上，没有观察到明显的相分离。我们的单层测量表明，与SSM相比，添加少量DOPC对DHSM的脂质堆积的干扰较小，表明DHSM分子之间的氢键更强。因此，在DHSM/DOPC二元双层中，DHSM分子可能由于DHSM诱导的氢键而局部积累形成DHSM富结构域。另一方面，由于DHSM和DOPC组件之间曲率的差异会在富DHSM和富DOPC结构域之间的边界处产生弹性约束，因此应防止DHSM的过度积累。氢键形成带来的能量优势和弹性约束带来的能量劣势之间的竞争可能导致l - α / l - α，在有限的组成范围内相分离。(C) 2014 Elsevier B.V.版权所有
Recently, DHSM, a minor constituent in naturally occurring SMs, was indicated to form a raft-like ordered phase more effectively than a naturally occurring form of SM because DHSM has greater potential to induce the intermolecular hydrogen bond. In order to examine the influence of the DHSM-induced hydrogen bond on die phase segregation, the thermal phase behavior of stearoyl-DHSM/DOPC binary bilayers was examined using calorimetry and fluorescence observation and compared with that of SSM/DOPC binary bilayers. Results revealed that the DHSM/DOPC bilayers undergo phase segregation between two La phases within a limited compositional range. On the other hand, apparent phase separation was not observed above main transition temperature in SSM/DOPC mixtures. Our monolayer measurements showed that the lipid packing of DHSM is less perturbed than that of SSM by the addition of small amount of DOPC, indicating a stronger hydrogen bond between DHSM molecules. Therefore, in DHSM/DOPC binary bilayers, DHSM molecules may locally accumulate to form a DHSM-rich domain due to a DHSM-induced hydrogen bond. On the other hand, excess accumulation of DHSM should be prevented because the difference in the curvature between DHSM and DOPC assemblies causes elastic constraint at the domain boundary between the DHSM-rich and DOPC-rich domains. Competition between the energetic advantages provided by formation of the hydrogen bond and the energetic disadvantage conferred by elastic constraints likely results in L-alpha/L-alpha, phase separation within a limited compositional range. (C) 2014 Elsevier B.V. All rights reserved.