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DMPC 磷脂膜的 13C 和 1H NMR 谱的水合作用和温度依赖性及其晶体态的完全共振归属。

Hydration and temperature dependence of 13C and 1H NMR spectra of the DMPC phospholipid membrane and complete resonance assignment of its crystalline state.

机构信息

Suntory Foundation for Life Sciences, Bioorganic Research Institute, Mishima-Gun, Osaka, Japan.

出版信息

J Phys Chem B. 2011 Dec 22;115(50):14991-5001. doi: 10.1021/jp208958a. Epub 2011 Nov 30.

Abstract

Inhomogeneous line broadening due to conformational distributions of molecules is one of the troublesome problems in solid-state NMR spectroscopy. The best possible way to avoid it is to crystallize the sample. Here, we present a highly resolved (13)C cross-polarization (CP) magic angle spinning (MAS) NMR spectrum of the highly ordered crystalline 1,2-dimyrystoyl-sn-glycero-3-phosphocholine (DMPC) and completely assigned it using two-dimensional (2D) solid-state NMR spectra, dipolar heteronuclear correlation (HETCOR) spectra, scalar heteronuclear J coupling based chemical shift correlation (MAS-J-HMQC) spectra, and Dipolar Assisted Rotational Resonance (DARR) spectra. A comparison between assigned chemical shift values by solid-state NMR in this study and the calculated chemical shift values for X-ray crystal DMPC structures shows good agreement, indicating that the two isomers in the crystalline DMPC take the same conformation as the X-ray crystal structure. The phase diagram of the low hydration level of DMPC (3 ≤ n(W) ≤ 12) determined by (1)H and (13)C NMR spectra indicates that DMPC takes a crystalline state only in a very narrow region around n(W) = 4 and T < 313 K. These findings provide us with conformational information on crystalline DMPC and the physical properties of DMPC at a low hydration level and can possibly help us obtain a highly resolved solid-state NMR spectrum of microcrystalline membrane-associated protein samples.

摘要

由于分子构象分布导致的不均匀线宽是固态 NMR 光谱学中的一个难题。避免这个问题的最好方法是结晶样品。在这里,我们呈现了高度有序的结晶 1,2-二肉豆蔻酰-sn-甘油-3-磷酸胆碱(DMPC)的高分辨率(13)C 交叉极化(CP)魔角旋转(MAS)NMR 谱,并使用二维(2D)固态 NMR 谱、偶极异核相关(HETCOR)谱、基于标量异核 J 偶合的化学位移相关(MAS-J-HMQC)谱和偶极辅助旋转共振(DARR)谱对其进行了完全归属。本研究中通过固态 NMR 归属的化学位移值与 X 射线晶体 DMPC 结构的计算化学位移值进行比较,结果表明两者吻合较好,表明结晶 DMPC 中的两种异构体与 X 射线晶体结构具有相同的构象。通过(1)H 和(13)C NMR 谱确定的低水合水平(3≤n(W)≤12)的 DMPC 相图表明,DMPC 仅在 n(W)=4 左右和 T<313 K 的非常窄的区域内呈结晶态。这些发现为我们提供了结晶 DMPC 的构象信息和低水合水平下 DMPC 的物理性质,可能有助于我们获得微晶膜相关蛋白样品的高分辨率固态 NMR 谱。

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