Effect of Cholesterol on the Formation of an Interdigitated Gel Phase in Lysophosphatidylcholine and Phosphatidylcholine Binary Mixtures.

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概要

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• We previously reported that 1, 2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) forms an interdigitated gel phase in the presence of 1-palmitoyl-sn-glycero-3-phosphocholine (16:0LPC) at concentrations below 30 mol%. In the present investigation, fluorescent probe 1, 6-diphenyl-1, 3, 5-hexatriene (DPH), X-ray diffraction, and differential scanning calorimetry (DSC) were used to investigate the effect of cholesterol on the phase behavior of 16:0LPC/DPPC binary mixtures. At 25°C, 30 mol% 16:0LPC significantly decreases the DPH fluorescence intensity during the transition of DPPC from the Lβ phase to the LβI phase. However, the addition of cholesterol to 16:0LPC/DPPC mixtures results in a substantial increase in fluorescence intensity. The changes in DPH fluorescence intensity reflect the probe's redistribution from an orientation parallel to the acyl chain to the center of the bilayer, suggesting a bilayer structure transition from interdigitation to noninterdigitation. The normal repeat period of small angle X-ray diffraction patterns can be restored and a reflection appears at 0.42nm with a broad shoulder around 0.41nm in wide angle X-ray diffraction patterns when 10 mol% cholesterol is incorporated into 30 mol% 16:OLPC/DPPC vesicles, indicating that the mixtures are in the gel phase (Lβ). Moreover, DSC results demonstrate that 10 mol% cholesterol is sufficient to significantly decrease the main enthalpy, cooperativity and lipid chain melting of 30 mol% 16:OLPC/DPPC binary mixtures, which are LβI, indicating that the transition of the interdigitated phase is more sensitive to cholesterol than that of the noninterdigitated phase. Our data imply that the interdigitated gel phase induced by 16:0LPC is prevented in the presence of 10 mol% cholesterol, but unlike ethanol, an increasing concentration of 16:0LPC is not able to restore the interdigitation structure of the lipid mixtures.

• 社団法人 日本生化学会の論文

著者

• Lu Jing-ze

  National Laboratory Of Biomacromolecules Institute Of Biophysics Academia Sinica

• Chen Jian-wen

  National Laboratory Of Biomacromolecules Institute Of Biophysics Academia Sinica

• Hao Yi-heng

  National Laboratory Of Biomacromolecules Institute Of Biophysics Academia Sinica

関連論文

• The Behaviors of Ca^-ATPase Embedded in Interdigitated Bilayer
• Effect of Cholesterol on the Formation of an Interdigitated Gel Phase in Lysophosphatidylcholine and Phosphatidylcholine Binary Mixtures^1
• More Ordered, Convex Ganglioside-Enriched Membrane Domains : The Effects of GM_1 on Sphingomyelin Bilayers Containing a Low Level of Cholesterol
• Anisodamine Causes the Changes of Structure and Function in the Transmembrane Domain of the Ca^-ATPase from Sarcoplasmic Reticulum
• Effect of Cholesterol on the Formation of an Interdigitated Gel Phase in Lysophosphatidylcholine and Phosphatidylcholine Binary Mixtures.

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