EFFECT OF SHORT-CHAIN PRIMARY ALCOHOLS ON FLUIDITY AND ACTIVITY OF SARCOPLASMIC-RETICULUM MEMBRANES
EFFECT OF SHORT-CHAIN PRIMARY ALCOHOLS ON FLUIDITY AND ACTIVITY OF SARCOPLASMIC-RETICULUM MEMBRANES
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DOI：
10.1021/bi00365a017
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发表时间：
1986-08-26
期刊：
影响因子：
2.9
通讯作者：
MADEIRA, VMC
中科院分区：
文献类型：
--
作者：
ALMEIDA, LM;VAZ, WLC;MADEIRA, VMC
用荧光探针1，3-二（1-芘基）丙烷，差示扫描量热法和X-射线衍射的分子内激基缔合物的形成被用来评估乙醇，1-丁醇，和1-己醇对模型膜，肌浆网（SR）脂质和天然SR膜的双层组织的影响。这些醇对膜具有流化作用，降低了DMPC的主转变温度，但只有1-己醇改变了相转变的协同性，并显着增加了DMPC双层的厚度。还研究了这三种醇与SR钙泵的相互作用。ATP的水解和耦合的Ca 2+摄取对三种醇的敏感性不同。乙醇和正丁醇抑制Ca ~（2+）的摄取，而正己醇则促进Ca ~（2+）的摄取，但乙醇和正己醇对Ca ~（2+）/ATP的能量效率影响不显著，而正丁醇在高浓度时能使Ca ~（2+）与ATP解偶联。醇类对SR膜活性的不同影响排除了基于脂质双层中诱导的流动性变化的单一作用机制。根据链长的不同，醇在不同的区域与SR膜相互作用，从而不同地干扰Ca 2+泵活性。
Intramolecular excimer formation with the fluorescent probe 1,3-di(1-pyrenyl)propane, differential scanning calorimetry, and X-ray diffraction were used to assess the effect of ethanol, 1-butanol, and 1-hexanol on the bilayer organization in model membranes, sarcoplasmic reticulum (SR) lipids and native SR membranes. These alcohols have fluidizing effects on membranes and lower the main transition temperature of dimyristoylphosphatidylcholine (DMPC), but only 1-hexanol alters the cooperativity of the phase transition and significantly increases the thickness of DMPC bilayers. The interaction of the three alcohols with the SR Ca2+ pump was also investigated. Hydrolysis of ATP and coupled Ca2+ uptake are differently sensitive to the three alcohols. Whereas ethanol and 1-butanol inhibited the Ca2+ uptake, 1-hexanol stimulated it. Nevertheless, the energetic efficiency of the pump (Ca2+/ATP) is not significantly affected by ethanol or 1-hexanol, but uncoupling was observed with 1-butanol at high concentrations. The different effects of alcohols on the activity of SR membranes rule out an unitary mechanism of action on the basis of fluidity changes induced in the lipid bilayer. Depending on the chain length, the alcohols interact with the SR membranes in different domains, perturbing differently the Ca2+-pump activity.