A solid-state NMR study of phospholipid-cholesterol interactions: Sphingomyelin-cholesterol binary systems
A solid-state NMR study of phospholipid-cholesterol interactions: Sphingomyelin-cholesterol binary systems
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DOI：
10.1016/s0006-3495(02)73917-9
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发表时间：
2002-09-01
影响因子：
3.4
通讯作者：
Hamilton, JA
中科院分区：
文献类型：
--
作者：
Guo, W;Kurze, V;Hamilton, JA
我们用固体核磁共振技术研究了胆固醇(Chol)与牛脑鞘磷脂(SM)的相互作用，并比较了Chol与具有相似凝胶-液晶转变温度的二棕榈酰磷脂酰胆碱(DPPC)的相互作用。H-1-、P-31-和C-13-MASNMR从未标记的脑SM和Chol的多层分散体中产生高分辨率光谱，用于分析化学位移和线宽。此外，具有特定氚标记的定向脂膜的H-2-核磁共振谱给出了膜的有序性和流动性的信息。CHOL打乱了纯SM的凝胶相，增加了液晶相中的酰链有序度。根据C-13化学位移推测，SM和DPPC的有序和无序液晶相(L-α(O)和L-α(D))之间的边界相似。CHOL在SM中的溶解极限类似于50摩尔%，与先前报道的DPPC膜的溶度极限相同。我们没有发现在Chol和SM的酰胺基团之间存在特定的氢键的证据。探针分子D31-SN1-DPPC在SM中的有序参数比在DPPC中略高，但在5%和60%Chol时，除末端基团外，其余碳在SM中的有序参数没有显著差异。这些研究表明，CHOL与DPPC和SM相互作用的方式有总体上的相似性，但也有一些细微的差异。在典型的生物膜环境中，SM中饱和脂肪酰链的比例高于其他磷脂，这可能是影响与Chol相互作用的最重要因素。
We used solid-state NMR techniques to probe the interactions of cholesterol (Chol) with bovine brain sphingomyelin (SM) and for comparison of the interactions of Chol with dipalmitoylphosphatidylcholine (DPPC), which has a similar gel-to-liquid crystalline transition temperature. H-1-, P-31-, and C-13-MASNMR yielded high-resolution spectra from multilamellar dispersions of unlabeled brain SM and Chol for analysis of chemical shifts and linewidths. In addition, H-2-NMR spectra of oriented lipid membranes with specific deuterium labels gave information about membrane ordering and mobility. Chol disrupted the gel-phase of pure SM and increased acyl chain ordering in the liquid crystalline phase. As inferred from C-13 chemical shifts, the boundaries between the ordered and disordered liquid crystalline phases (L-alpha(o) and L-alpha(d)) were similar for SM and DPPC. The solubility limit of Chol in SM was similar to50 mol %, the same value as previously reported for DPPC membranes. We found no evidence for specific H-bonding between Chol and the amide group of SM. The order parameters of a probe molecule, d31-sn1-DPPC, in SM were slightly higher than in DPPC for all carbons except the terminal groups at 30 mol % but were not significantly different at 5 and 60 mol % Chol. These studies show a general similarity with some subtle differences in the way Chol interacts with DPPC and SM. In the environment of a typical biomembrane, the higher proportion of saturated fatty acyl chains in SM compared to other phospholipids may be the most significant factor influencing interactions with Chol.