Differential scanning calorimetric studies of ethanol interactions with distearoylphosphatidylcholine: transition to the interdigitated phase.
Differential scanning calorimetric studies of ethanol interactions with distearoylphosphatidylcholine: transition to the interdigitated phase.
复制标题
乙醇与二硬脂酰磷脂酰胆碱相互作用的差示扫描量热研究：过渡到叉指相。
DOI：
10.1021/bi00497a015
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发表时间：
1990
期刊：
影响因子：
2.9
通讯作者：
Cutrera,TA
中科院分区：
文献类型：
--
作者：
Rowe,ES;Cutrera,TA
1990年3月5日毕业，堪萨斯城堪萨斯大学医学中心生物化学和分子生物学系，堪萨斯城66103，退伍军人管理局医疗中心，堪萨斯城64128；摘要：乙醇和其他两亲性分子诱导饱和样链磷脂酰胆碱（PC’s）形成完全交叉的凝胶相已经得到了很好的证实。我们之前已经证明乙醇对PC中交叉指相的诱导取决于酒精浓度、脂质链长度和温度[Nambí， P., Rowe， ES, & McIntosh， T. J.(1988) Biochemistry 27,9175 -9182]。在本研究中，我们使用高灵敏度差示扫描量热法研究了二硬脂酰磷脂酰胆碱在非交叉指相和交叉指相之间的转变。L/到L^ I转变的焓大约是在没有乙醇的情况下发生的Lf到P/转变的焓的一半。这些转变的可逆性也通过采用加热和冷却扫描来研究，以便建立最稳定的相作为温度和乙醇浓度的函数。已经证明，过渡到交叉相是可逆的，作为温度的函数。对反向转变（LgI到L/）的动力学研究表明，这种转变可能非常缓慢，需要数周才能完成。反应速率取决于温度和乙醇浓度。缓慢的相位变化意味着脂质可以长时间以非最稳定状态的相结构存在。这种类型的脂质行为的生物学意义在于，生物膜的相结构可能不仅取决于存在的脂质最稳定的相结构，还取决于合成途径或其他动力学变量。指间质相是最近公认的脂质稳定相态之一（McDaniel等人，1983；McIntosh等人，1983；rank等人，1977；Huang等人，1983；Slater和Huang， 1988）。1983年，我们发现乙醇对不饱和样链磷脂酰胆碱（PC’s） 1的熔化温度有双相影响（Rowe, 1983），随后又证明乙醇诱导PC的间指化（Simon & McIntosh, 1984; Simon et al., 1986）。在类链PC中，它是由多种添加剂引起的，包括甘油、甲醇、乙二醇、苯甲醇、氯丙嗪、丁卡因、乙醇、硫氰酸盐离子（McDaniel等人，1983；McIntosh等人，1983；Cunningham和Lis, 1986； Slater和Huang， 1988），以及“醇类”直至庚醇（Rowe和Nelson， 1990）。在不添加添加剂的情况下，双棕榈酰磷脂酰胆碱（DPPC）和二硬脂酰磷脂酰胆碱（dsc）在静水压力增大时进入指间相（Braganza & Worcester, 1986; Prasad et al., 1987）。DPPC的醚类似物二十六基磷脂酰胆碱（DHPC）在正常压力下以交叉状态存在
Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, KansasCity, Kansas 66103, and Veterans Administration Medical Center, Kansas City, Missouri 64128 Received March 5, 1990; Revised Manuscript Received August 8, 1990 abstract: It is well established that ethanol and other amphipathic molecules induce the formation of a fully interdigitated gel phase in saturatedlike-chain phosphatidylcholines (PC’s). We have previously shown that the induction of interdigitation in PC’s by ethanol is dependent upon the alcohol concentration, the lipid chain length, and the temperature [Nambí, P., Rowe, ES, & McIntosh, T. J.(1988) Biochemistry 27, 9175-9182], In thepresent study, we have used high-sensitivity differential scanning calorimetry to investigate the transitions of distearoylphosphatidylcholine between the noninterdigitated and the interdigitated phases. The enthalpy of the L/to L^ I transition is approximately half that of the Lf to P/transition which occurs in the absence of ethanol. The reversibility of these transitions has also been investigated by employing both heating and cooling scans in order to establish the most stable phases as a function of temperature and ethanol concentration. It has been demonstrated that the transition to the interdigitated phase is reversible as a function of temperature. Kinetic studies on the reverse transition (LgI to L/) demonstrate that this transition can be very slow, requiring weeks to reachcompletion. The rate depends upontemperature and ethanol concentration. The slow phase changes mean that the lipid can exist for long periods of time in a phase structure which is not the most stable state. The biological significance of this type of lipid behavior is the implicationthat the phase structure of biological membranes may depend not only on the most stable phase structure of the lipids present but also on the synthetic pathway or other kinetic variables.Interdigitated lipid phases are among the most recently recognized stable phase states for lipids (McDaniel et al., 1983; McIntosh et al., 1983; Ranck et al., 1977; Huang et al., 1983; Slater & Huang, 1988). In 1983, we showed that ethanolhad a biphasic effect on the melting temperature of disaturated like-chain phosphatidylcholines (PC’s) 1 (Rowe, 1983) which was subsequently shown to be causedby induction of inter-digitation in the PC by ethanol (Simon & McIntosh, 1984; Simon et al., 1986). In like-chain PC’s, it is induced by a variety of additives including glycerol, methanol, ethylene glycol, benzyl alcohol, chlorpromazine, tetracaine, ethanol, thiocyanate ion (McDaniel et al., 1983; McIntosh et al., 1983; Cunningham & Lis, 1986; Slater & Huang, 1988), and the «-alcohols up to heptanol (Rowe & Nelson, 1990). In the absence of additives, dipalmitoylphosphatidylcholine (DPPC) and distearoylphosphatidylcholine (DSPC) go into the interdigitated phase at increased hydrostatic pressure (Braganza & Worcester, 1986; Prasad et al., 1987). The ether analogue of DPPC, dihexadecylphosphatidylcholine (DHPC), exists in the interdigitated state under normal pressures in the absence