The Long-Chain Sphingoid Base of Ceramides Determines Their Propensity for Lateral Segregation
The Long-Chain Sphingoid Base of Ceramides Determines Their Propensity for Lateral Segregation
复制标题
DOI：
10.1016/j.bpj.2017.01.016
复制
发表时间：
2017-03-14
影响因子：
3.4
通讯作者：
Slotte, J. Peter
中科院分区：
文献类型：
--
作者：
Al Sazzad, Md. Abdullah;Yasuda, Tomokazu;Slotte, J. Peter
我们研究了神经酰胺的长链碱基或N-连接酰基链的长度如何影响它们在1-棕榈酰-2-油酰-sn-甘油-3-磷酸胆碱（POPC）双层中的侧向分离。横向偏析和富神经酰胺相的形成，确定通过寿命分析的trans-parinaric酸（tPA）荧光。长链碱基的长度越长（在N-棕榈酰神经酰胺中为d16：1、d17：1、d18：1、d19：1和d20：1），侧向分离和富神经酰胺相形成所需的神经酰胺就越少。当基于鞘氨醇（d18：1）的神经酰胺具有增加长度的N-连接酰基链（14：0和16：0-20：0，以一个碳增量）时，观察到类似但弱得多的趋势。从tPA荧光的最长寿命组分确定的富神经酰胺相的表观横向堆积也与长链碱基长度强烈相关，但与N-酰基链长度不那么强烈。最后，我们比较了两个神经酰胺类似物具有相同的碳数（d16：1/17：0或d20：1/13：0），并观察到，与较短的鞘氨醇碱类似物相比，具有较长鞘氨醇碱的类似物在较低的双层浓度下分离到富含神经酰胺的相。由d20：1/13：0神经酰胺形成的凝胶相也比由d16：1/17：0神经酰胺形成的凝胶相更耐热。POPC中10 mol %硬脂酰神经酰胺的H-2 NMR数据也表明，在可比的链位置和温度下，长链碱基比酰基链更有序。我们得出的结论是，在决定富含神经酰胺的凝胶相的侧向分离和其中的分子间相互作用方面，神经酰胺的长链碱基长度比酰基链长度更重要。
We examined how the length of the long-chain base or the N-linked acyl chain of ceramides affected their lateral segregation in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayers. Lateral segregation and ceramide-rich phase formation was ascertained by a lifetime analysis of trans-parinaric acid (tPA) fluorescence. The longer the length of the long-chain base (d16:1, d17:1, d18:1, d19:1, and d20:1 in N-palmitoyl ceramide), the less ceramide was needed for the onset of lateral segregation and ceramide-rich phase formation. A similar but much weaker trend was observed when sphingosine (d18: 1)-based ceramide had N-linked acyl chains of increasing length (14:0 and 16:0-20:0 in one-carbon increments). The apparent lateral packing of the ceramide-rich phase, as determined from the longest-lifetime component of tPA fluorescence, also correlated strongly with the long-chain base length, but not as strongly with the N-acyl chain length. Finally, we compared two ceramide analogs with equal carbon numbers (d16:1/17:0 or d20:1/13:0) and observed that the analog with a longer sphingoid base segregated at lower bilayer concentrations to a ceramide-rich phase compared with the shorter sphingoid base analog. The gel phase formed by d20:1/13:0 ceramide also was more thermostable than the gel phase formed by d16:1/17:0 ceramide.H-2 NMR data for 10 mol % stearoyl ceramide in POPC also showed that the long-chain base was more ordered than the acyl chain at comparable chain positions and temperatures. We conclude that the long-chain base length of ceramide is more important than the acyl chain length in determining the lateral segregation of the ceramide-rich gel phase and intermolecular interactions therein.