Molecular organization and motions of cholesteryl esters in crystalline and liquid crystalline phases: a 13C and 1H magic angle spinning NMR study.
Molecular organization and motions of cholesteryl esters in crystalline and liquid crystalline phases: a 13C and 1H magic angle spinning NMR study.
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结晶相和液晶相中胆固醇酯的分子组织和运动：13C 和 1H 魔角旋转 NMR 研究。
DOI：
10.1021/bi00086a009
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发表时间：
1993
期刊：
影响因子：
2.9
通讯作者：
Hamilton,JA
中科院分区：
文献类型：
--
作者：
Guo,W;Hamilton,JA
摘要：胆固醇酯是血浆脂蛋白和动脉粥样硬化病变的主要脂质成分。几种胆甾醇酯[油酸酯]的结晶相和液晶相（C18：1，-9），芥酸（C22：1，-9）、己酸酯（C6：0）、癸酸酯（C10：0）、十一烷酸酯（C11：0）、肉豆蔻酸酯（C14：0）、棕榈酸酯（C16：0）和硬脂酸酯（C18：0）]的天然丰度~（13）C核磁共振谱（MASNMR）研究。魔角旋转，高功率质子去耦，和交叉极化转移得到的光谱结晶胆固醇酯高度解析。酰基链碳比质子化的类固醇环碳具有更窄的线，反映了晶体中的微分运动（具体地，酰基链中的运动比类固醇环中的运动更快）。酯结晶成单层II型结构，其中所有的分子是等效的，引起了一个单一的共振为每个碳;酯的单层I型和双层结构，其中有两种类型的非等效分子在晶胞中，有两个共振（等强度和线宽）的几个碳，如羰基和甾环C5和C6。液晶相的光谱没有显示出相同碳的信号不等效，并且没有通过交叉极化转移而增强。这些变化是液晶中分子运动增加的结果，这平均了非等效环境并减少了偶极相互作用。胆甾相和近晶相液晶相的区别是更广泛的C= 0，C5，和C6的信号相比，近晶相的胆甾相。在近晶相中，所有胆固醇酯的相应碳的化学位移是相似的，并且接近于具有单层II结构的结晶酯的化学位移，这表明近晶相具有类似于单层II晶体结构的结构特征。因此，13 C MASNMR是研究结晶和液晶胆固醇酯的结构和运动的有力方法。1H MASNMR谱没有给出分子水平上的详细信息，但是对于每个相是唯一的，并且提供了用于区分固体、近晶相、非晶相和各向同性相的简单和快速的方法。它们也是动脉粥样硬化斑块中脂质的主要组成部分（Small，1988）。因为它们是弱极性分子，胆固醇酯在磷脂界面中具有非常低的溶解度（Gorrissen等人，1980;汉密尔顿等人，1982，1983）并形成分离的相，其可由纯的或接近纯的胆甾醇酯组成。因此，彻底了解各种物理状态下纯胆固醇酯的聚集特性在正常和病理生理学中都很重要。胆固醇酯的多晶型和介晶性已经通过不同的物理方法如差示扫描量热法（Davis等人，1970）、X射线衍射（Craven，1986; Gao & Craven，1986）、电子衍射（Dorset，1985）、偏光显微镜（Gray，1962）和核磁共振（NMR）光谱（汉密尔顿等人，1977; Kroon，1981; Ginsburg等人，1982; Croll等人，1985年，1986年）。虽然显微镜和量热法是研究相变行为的信息丰富和方便的方法，但它们通常提供
Revised Manuscript Received June 11, 1993 abstract: Cholesteryl esters are a major lipid constitutent of plasma lipoproteins and atherosclerotic lesions. Crystalline and liquid crystalline phases of several cholesteryl esters [oleate (C18: l,-9), erucate (C22: l,-9), hexanoate (C6: 0), decanoate (C10: 0), undecanoate (C11: 0), myristate (C14: 0), palmitate (C 16: 0), and stearate (C 18: 0)] have been studied by natural abundance 13C NMR with magic angle spinning (MASNMR) at 75 MHz (7.05 T). Spectra obtained with magic angle spinning, high-power proton decoupling, and cross-polarization transfer were highly resolved for crystalline cholesteryl esters. Acyl chain carbons had narrower lines than protonated steroidring carbons, reflecting differential motions in the crystal (specifically, more rapid motions in the acyl chain than in the steroid ring). Esters which crystallize into the monolayer type II structure, in which all molecules are equivalent, gave rise to a single resonance for each carbon; esters of the monolayer type I and bilayer structures, in which there are two types of nonequivalent molecules in the unit cell, had two resonances(equal intensity and linewidth) for several carbons, such as the carbonyl and the steroid ring C5 and C6. Spectra for liquid crystalline phases did not show inequivalence of signals for the same carbon and were not enhanced by cross-polarization transfer. These changes are a result of increased molecular motions in the liquid crystals, which average the nonequivalent environments and reduce the dipolar interactions. Cholesteric and smectic liquid crystalline phases were distinguished by the broader C= 0, C5, and C6 signals for the cholesteric compared with the smectic phase. In the smectic phase, chemical shifts of corresponding carbons of allcholesteryl esters are similar and are close to those for crystalline esters with a monolayer II structure, which suggests that the smectic phasehas structural features resembling the monolayer II crystal structure. 13C MASNMR is thus a powerful approach for examining structureand motions of crystalline and liquid-crystalline cholesteryl esters.* H MASNMR spectra did not give as detailed information on the molecular level but were unique for each phase and provided a simple and quick method for distinguishing the solid, smectic, cholesteric, and isotropic phases.Cholesteryl esters serve as a transport and storage form of cholesterol in mammals (Brown & Goldstein, 1986; Jones & Glomset, 1985). They also constitute a major fraction of the lipids present in atherosclerotic plaques (Small, 1988). Because they are weakly polar molecules, cholesteryl esters have a very low solubility in phospholipid interfaces (Gorrissen et al., 1980; Hamilton et al., 1982, 1983) and form separate phases, which can consist of pure or nearly pure cholesteryl esters. A thorough understanding of the aggregation properties of pure cholesteryl esters in various physical states is therefore important in both normal and pathophysiology. The polymorphism and mesomorphism of cholesteryl esters have been extensively studied by different physical methods such as differential scanning calorimetry (Davis et al., 1970), X-ray diffraction (Craven, 1986; Gao & Craven, 1986), electron diffraction (Dorset, 1985), polarizing microscopy (Gray, 1962), and nuclear magnetic resonance(NMR) 1 spectroscopy (Hamilton et al., 1977; Kroon, 1981; Ginsburg et al., 1982; Croll et al., 1985, 1986). Although microscopy and calorimetry are informative and convenient methods for the study of phase transition behavior, they usually provide
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醋酸叔丁酯五种晶型的晶体结构、固态NMR谱和氧反应性
DOI：
--
发表时间：
1988
期刊：
影响因子：
--
作者：
S. Byrn;P. Sutton;B. Tobias;J. Frye;P. Main
通讯作者：
P. Main
胆固醇链烷酸酯中间相中的氘核磁共振和分子排序
DOI：
--
发表时间：
1981
期刊：
影响因子：
--
作者：
Z. Luz;R. Poupko;E. Samulski
通讯作者：
E. Samulski
鸡蛋磷脂酰胆碱囊泡中三油酸甘油酯和胆固醇油酸酯的溶解。
DOI：
--
发表时间：
1983
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Hamilton,JA;Miller,KW;Small,DM
通讯作者：
Small,DM
影响因子：
56.9
作者：
BROWN, MS;GOLDSTEIN, JL
通讯作者：
GOLDSTEIN, JL
磷脂酰胆碱囊泡中选择性氘代胆固醇酯的氘磁共振。
影响因子：
2.9
作者：
H. Gorrissen;A. P. Tulloch;R. J. Cushley
通讯作者：
R. J. Cushley