CA2+-INDUCED LATERAL PHASE SEPARATIONS IN PHOSPHATIC ACID-PHOSPHATIDYLCHOLINE MEMBRANES
CA2+-INDUCED LATERAL PHASE SEPARATIONS IN PHOSPHATIC ACID-PHOSPHATIDYLCHOLINE MEMBRANES
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DOI：
10.1016/0005-2736(74)90176-x
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发表时间：
1974-01-01
期刊：
影响因子：
--
通讯作者：
OHNISHI, SI
中科院分区：
文献类型：
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作者：
ITO, T;OHNISHI, SI
用磷脂自旋标记法研究了钙离子对磷脂酸-磷脂酰胆碱膜的影响。自旋标记的磷脂酸-磷脂酰胆碱膜和自旋标记的磷脂酸-磷脂酰胆碱膜的ESR谱在加入CaCl2后立即交换展宽。这些变化直接和明确地表明，钙离子诱导的自旋标记磷脂酰胆碱的聚集和自旋标记的磷脂酸通过钙离子螯合桥联在二元磷脂膜上的聚集。在钙离子螯合的聚集体中，磷脂酸烷基链的运动大大减少，脂质分子更加紧密地堆积在一起。团簇和聚集体以斑块的形式形成，其大小取决于组分。Ba2+和Sr2+诱导横向相分离的程度与Ca2+相同。镁离子也是有效的，但程度较小。在酸性溶液(pH=5.5)中，Ca~(2+)诱导的侧向相分离的程度比在碱性溶液(pH=7.9)中略小。并与文献报道的磷脂酰丝氨酸-磷脂酰胆碱膜的结果进行了比较，讨论了侧向相分离的必要条件。
The effects of Ca2+on phosphatidic acid-phosphatidylcholine membranes have been studied using phospholipid spin labels. ESR spectra of spin-labeled phosphatidic acid-phosphatidylcholine membranes and phosphatidic acid-spin-labeled phosphatidylcholine membranes are exchange-broadened immediately upon addition of CaCl2. These changes directly and conclusively indicate Ca2+-induced clustering of spin-labeled phosphatidylcholine and aggregation of spin-labeled phosphatidic acid bridged by Ca2+-chelation in the binary phopholipid membranes. In the Ca2+-chelated aggregates, the motions of the alkyl chains of phosphatidic acid are greatly reduced and the lipid molecules are more closely packed. The clusters and aggregates are formed in patches and the sizes are dependent on the fractions. Ba2+and Sr2+induce the lateral phase separations to the same extent as Ca2+. Mg2+is also effective but to a lesser extent. In acid solutions (pH 5.5), the Ca2+-induced lateral phase separations are of slightly lesser extent than in alkaline solution (pH 7.9). These results are compared with those for phosphatidylserine-phosphatidylcholine membranes reported previously and necessary conditions for the lateral phase separations are discussed.