Based on neutron spin-echo (NSE), solid-state NMR, and molecular dynamics (MD) simulations, we report clear evidence that cholesterol stiffens 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) membranes (1). Contrary to statements by Nagle et al. (2), the relaxations measured by NSE and NMR directly relate to elastic membrane constants (3, 4). While both NSE and NMR spectroscopy measure the time-averaged 𝜏-decay, 〈A(t)A(t+τ)〉, the data analysis methods separate the mean-square amplitude (MSA) from membrane dynamics, providing information about equilibrium and dynamical bilayer properties (4). In the case of isotropic systems (simplest case), the MSA =〈At2〉 and the time average 〈A(t)〉 is zero. However, for ordered systems such as lipid bilayers, the time average is nonzero …

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回复 Nagle 等人：胆固醇对脂质膜的普遍硬化作用 [物理科学]

基于中子自旋回波 (NSE)、固态 NMR 和分子动力学 (MD) 模拟，我们报告了明确的证据表明胆固醇会使 1,2-二油酰-sn-甘油-3-磷酸胆碱 (DOPC) 膜变硬( 1 ) . 与 Nagle 等人的说法相反。( 2 )，NSE 和 NMR 测量的弛豫与弹性膜常数直接相关 ( 3 , 4 )。虽然 NSE 和 NMR 光谱都测量时间平均𝜏 -衰减，〈一种(吨)一种(吨+τ)〉，数据分析方法将均方振幅 (MSA) 与膜动力学分开，提供有关平衡和动态双层特性的信息 ( 4 )。在各向同性系统的情况下（最简单的情况），海事局 =〈一种吨2〉 和时间平均值 〈一种(吨)〉为零。然而，对于脂质双层等有序系统，时间平均值是非零的……