Contrasting Effects of a Rigid Core and an Alkyl Chain in nCB on the Phase Behavior of Lipid Bilayers

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• 作者：Hatsuho Usuda ; Mafumi Hishida ; Yasuhisa Yamamura ; Kazuya Saito
• 刊名：Langmuir
• 出版年：2016
• 出版时间：June 14, 2016
• 年：2016
• 卷：32
• 期：23
• 页码：5966-5972
• 全文大小：322K
• 年卷期：0
• ISSN：1520-5827

文摘

Molecules incorporated into biomembranes often bear both a core and an alkyl chain in a single molecule (e.g., sterols). To clarify the effects of these two parts of a molecule, the phase behavior of a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayer containing 4-n-alkyl-4′-cyanobiphenyl (nCB) (n = 0–8) was investigated. The trends of the main transition temperature (T_m) with respect to n and of the pretransition temperature (T_p) with respect to nCB content changed at n = 3. It was therefore suggested that the two parts of the molecule had opposing effects on the phase behavior of DPPC bilayers. The core appears to perturb molecular ordering in the gel phase and lowers T_m (like cholesterol), while alkyl chains appear to order the lipids in the gel phase and raise T_m (like n-alkanes). In addition, T_m exhibits the so-called odd–even effect based on the alkyl chain length of the minor component, nCB. Depending on the value of n, the variation in T_p was dependent on the additive content, although the pretransition was rarely observed at high contents.