Stabilization of sphingomyelin interactions by interfacial hydroxyls ¡ª A study of phytosphingomyelin properties

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• 作者：Shishir Jaikishan ; J. Peter Slotte ; ^{jpslotte@abo.fi}
• 关键词：7SLPC ; 1-palmitoyl-2-stearoyl-(7-doxyl)-sn-glycero-3-phosphocholine ; CTL ; cholesta-5 ; 7 ; 9 (11)-trien-3-beta-ol ; DPH ; 1 ; 6-diphenyl-1 ; 3 ; 5-hexatriene ; Kx ; partitioning coefficient ; POPC ; 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine ; SM ; sphingomyelin ; Tm
• 刊名：Biochimica et Biophysica Acta (BBA)/Biomembranes
• 出版年：2013
• 出版时间：February, 2013
• 年：2013
• 卷：1828
• 期：2
• 页码：391-397
• 全文大小：489 K

文摘

D-ribo-phytosphingosines are biologically significant long-chain bases present in various sphingolipids from yeasts, fungi, plants and mammals. In this study we prepared phytopalmitoylsphingomyelin (phytoPSM) analogs based on the D-ribo-phytosphingosine base. The N-linked acyl chains were either 16:0, 2OH(R)16:0 (natural isomer), or 2OH(S)16:0. The gel-phase of phytoPSM was more stable than that of PSM (T_m 48.6 ¡ãC and 41.0 ¡ãC, respectively). The gel-liquid crystalline phase transition enthalpies were 9.1 ¡À 0.4 and 6.1 ¡À 0.3 kcal/mol for phytoPSM and PSM, respectively. An N-linked 2OH(R)16:0 in phytoPSM destabilized the gel phase relative to phytoPSM (by ~+ 6 ¡ãC, based on DPH anisotropy measurements), whereas 2OH(S)16:0 in phytoPSM stabilized it (by ~? 6 ¡ãC). All phytoPSM analogs formed sterol-enriched ordered domains in a fluid ternary bilayer, and those containing phytoPSM or 2OH(S)phytoPSM were more thermostable than the domains containing 2OH(R)phytoPSM or PSM. The affinity of cholestatrienol for POPC bilayers containing 20 mol % phytoPSM was higher than for comparable bilayers with an equal amount of PSM. The 2-hydroxylated acyl chains in phytoPSM did not markedly alter sterol affinity. We conclude that phytoPSM is a more ordered sphingolipid than PSM, and is fully capable of interacting with cholesterol.