Structure and thermotropic properties of mixed-chain phosphatidylcholine bilayer membranes
Structure and thermotropic properties of mixed-chain phosphatidylcholine bilayer membranes
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DOI：
10.1021/bi00299a020
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发表时间：
1984-02
期刊：
影响因子：
2.9
通讯作者：
E. Serrallach;G. Haas;G. Shipley
中科院分区：
文献类型：
--
作者：
E. Serrallach;G. Haas;G. Shipley
E. N.塞拉拉赫湾H. de哈斯和GG Shipley* 摘要：用X射线衍射和差示扫描量热法（DSC）研究了1-肉豆蔻酰-2-棕榈酰-L-磷脂酰胆碱（MPPC）和1-棕榈酰-2-肉豆蔻酰-L-磷脂酰胆碱（PMPC）的结构和热致性。在-3 ℃下长时间储存后，MPPC和PMPC的水合多层分散体在初始加热时显示出两个可比较的吸热转变。MPPC在26 ℃（AH= 8.0 kcal/mol MPPC）和34 ℃（AH= 8.1 kcal/mol MPPC）下发生转变; PMPC在较低温度17 ℃（AH= 7.7 kcal/mol PMPC）和27 ℃（AH= 7.8 kcal/mol PMPC）下发生转变。对于MPPC和PMPC来说，只有较高温度的转变是容易可逆的;随着低温下孵育时间的增加，与较低温度转变相关的焓逐渐恢复，这表明亚稳态和稳定相之间的转化（尽管动力学复杂）。X-射线衍射数据显示存在的双层结构和类似的图案的结构变化的加热水合（50重量%）的MPPC和PMPC。在低温相变区以下，用多种生物物理方法详细研究了甘油主链上1位和2位含有相同脂肪酰基链的1，2-二酰基-L-磷脂酰胆碱（PC）1的结构和性质。扫描量热法和X射线衍射法的结合在描述水合PC的热致转变和阐明伴随这些相变的结构变化方面特别有价值。例如，对于水合的1，2-二棕榈酰-L-磷脂酰胆碱（DPPC）和1，2-二肉豆蔻酰-L-磷脂酰胆碱（DMPC），DPPC在约35和41 ℃以及DMPC在约13和24 ℃的两个可逆转变对应于凝胶-*-
E. N. Serrallach, G. H. de Haas, and GG Shipley* abstract: The structure and thermotropic properties of hy-drated l-myristoyl-2-palmitoyl-L-phosphatidylcholine (MPPC) and l-palmitoyl-2-myristoyl-L-phosphatidylcholine (PMPC) have been studied by X-ray diffraction and differential scan-ning calorimetry (DSC). After prolonged storage at-3 C, hydrated multilamellar dispersions of both MPPC and PMPC show two endothermictransitions of comparable enthalpies on initial heating. MPPC undergoes transitions at 26 C (AH= 8.0 kcal/mol of MPPC) and 34 C (AH= 8.1 kcal/mol of MPPC); PMPCexhibits transitions at lower temperatures, 17 C (AH= 7.7 kcal/mol of PMPC) and 27 C (AH= 7.8 kcal/mol of PMPC). For both MPPC and PMPC, only the higher temperature transition is readily reversible; the enthalpy associated with the lower temperature transition is progressively recovered with increasing incubation time at low temperatures, suggesting conversions, albeitkinetically complex, between metastable and stable phases. X-ray diffraction data show the presence of bilayer structures and a similar pattern of structural changes on heating for hydrated (50 wt%) MPPC and PMPC. Belowthe low-temperaturetransition aAhe structure and properties of 1, 2-diacyl-L-phosphatidyl-cholines (PC) 1 containing identical fatty acyl chains in the 1 and 2 positions on the glycerol backbone have been studied in detail by a wide variety of biophysical methods. A com-bination of scanning calorimetry and X-ray diffraction methods has been particularly valuable in describing the thermotropic transitions exhibited by hydrated PCs and elucidating the structural changes accompanying these phase changes. For hydrated 1, 2-dipalmitoyl-L-phosphatidylcholine (DPPC) and 1, 2-dimyristoyl-L-phosphatidylcholine (DMPC), for example, the two reversible transitions at approximately 35 and 41 C for DPPC and 13 and 24 C for DMPC correspond to gel—*-