We present experimental measurements and analysis of the dynamics and the phase behaviour of saturated DMPC and unsaturated DOPC oriented multi-lamellar bilayers. Elastic and inelastic neutron scattering were used to directly probe the dynamical processes of these membrane systems on time and length scales relevant to the internal and localized motion of lipid monomers. Mobility in this regime can be informative in elucidating the local interactions responsible for material properties of these fluid lipid systems. DMPC and DOPC are structurally similar in terms of their membrane hydrophobic thickness; however, they exhibit different mechanical properties in terms of both elastic compressibility and bending moduli. The analyses suggest that the constraint imposed by the double bonds in DOPC acyl chains restricts atomic motion in both liquid and gel phases compared to DMPC. We discuss applications of molecular dynamics to further elucidate the atomic details of the dynamical processes. Such an understanding may suggest how membrane properties can be tuned using a variety of different lipid species.

中文翻译：

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饱和和不饱和取向脂质双层的弛豫动力学†

我们目前的实验测量和饱和的DMPC和不饱和的DOPC取向的多层双层的动力学和相行为的分析。弹性和非弹性中子散射被用来在与脂质单体的内部和局部运动有关的时间和长度尺度上直接探测这些膜系统的动力学过程。在阐明这种流体脂质系统物质特性的局部相互作用中，这种机制下的流动性可能是有益的。DMPC和DOPC的膜疏水厚度在结构上相似；然而，它们在弹性压缩率和弯曲模量方面表现出不同的机械性能。分析表明，与DMPC相比，DOPC酰基链中双键所施加的约束限制了液相和凝胶相中的原子运动。我们讨论分子动力学的应用，以进一步阐明动力学过程的原子细节。这样的理解可能表明如何使用各种不同的脂质种类来调节膜的性能。