Physical properties of erythrocyte ghosts that determine susceptibility to secretory phospholipase A2
Physical properties of erythrocyte ghosts that determine susceptibility to secretory phospholipase A2
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DOI：
10.1074/jbc.m010879200
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发表时间：
2001-06-22
影响因子：
4.8
通讯作者：
Bell, JD
中科院分区：
文献类型：
--
作者：
Harris, FM;Smith, SK;Bell, JD
人工膜可能对分泌型磷脂酶A（sPLA（2））的催化攻击具有抵抗力或敏感性，这取决于膜的物理性质。活细胞通常具有抵抗力，但在创伤、凋亡和/或细胞内钙显著升高期间变得敏感。研究了完整的红细胞和血影，以确定从人工系统中学到的原理是否适用于生物膜。膜的性质，如磷脂和/或蛋白质的组成，形态，和微观特征（如流动性）进行了操纵，通过制备鬼在不同的实验条件下，如在存在或不存在的二价阳离子与或不ATP。通过生物化学和物理方法（使用膜探针bis-pyrene和laurdan的荧光光谱和电子及双光子显微镜）评估每种膜制备物的性质，并与sPLA（2）活性进行比较。似乎最相关的性质是膜外表面上磷脂酰丝氨酸暴露的程度以及通过双芘和月桂烷检测到的膜物理状态的变化。具体地说，对sPLA（2）水解的脆弱性与双层顺序的增加有关，这显然反映了流动性减弱的膜区域的扩张，这些结果表明，从人工膜研究中确定的一般原则适用于生物系统。
Artificial membranes may be resistant or susceptible to catalytic attack by secretory phospholipase A, (sPLA(2)) depending on the physical properties of the membrane. Living cells are normally resistant but become susceptible during trauma, apoptosis, and/or a significant elevation of intracellular calcium. Intact erythrocytes and ghosts were studied to determine whether the principles learned from artificial systems apply to biological membranes. Membrane properties such as phospholipid and/or protein composition, morphology, and microscopic characteristics (e.g, fluidity) were manipulated by preparing ghosts under different experimental conditions such as in the presence or absence of divalent cations with or without ATP. The properties of each membrane preparation were assessed by biochemical and physical means (fluorescence spectroscopy and electron and two-photon microscopy using the membrane probes bis-pyrene and laurdan) and compared with sPLA(2) activity. The properties that appeared most relevant were the degree of phosphatidylserine exposure on the outer face of the membrane and changes to the membrane physical state detected by bis pyrene and laurdan, Specifically, vulnerability to hydrolysis by sPLA(2) was associated with an increase in bilayer order apparently reflective of expansion of membrane regions of diminished fluidity, These results argue that the general principles identified from studies with artificial membranes apply to biological systems.