EFFECT OF SONICATION ON STRUCTURE OF LECITHIN BILAYERS
EFFECT OF SONICATION ON STRUCTURE OF LECITHIN BILAYERS
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DOI：
10.1021/bi00774a024
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发表时间：
1972-01-01
期刊：
影响因子：
2.9
通讯作者：
CHAN, SI
中科院分区：
文献类型：
--
作者：
SHEETZ, MP;CHAN, SI
随着人们对膜结构和生物运输的兴趣的增加，已经刺激了易于制备的模型膜系统的发展，这些模型膜系统可以容易地操作以阐明生物膜的一些物理和化学性质。特别是对磷脂双层有很大的兴趣。形成双层的脂质在水中的简单悬浮液产生含有许多不同大小的同心囊泡的多层结构（Bangham和Horne，1964）。虽然许多关于这些模型膜的双层相的结构问题可以从这些多层结构的研究中推导出来（Papahadjopoulos和米勒，1967），但它们不适合用于转运研究（Bangham，1972）。此外，每个多层单元含有未知数量的磷脂双分子层，由未知量的水分隔，其有序状态不清楚。然而，通过长时间的超声照射可以获得均匀的α-磷脂酰胆碱囊泡。这些囊泡是直径约250 A的封闭球体，每个由封闭一定体积水溶液的单个连续脂质双层膜组成（Huang，1969）。近年来，这种囊泡已被广泛用作双分子脂质层状相结构研究的模型系统，并且与Bangham（1968）的非超声处理制备相反，已被用于许多生理化学和运输研究（Kornberg和McConnell，1971 a，B; Lee等人，一九七二年; Papahadjopoulos和Watkins，1967; Bangham，1972）。在过去的几年中，已经进行了许多尝试来通过核磁共振光谱表征磷脂双层（Penkett等人，1968; Finer等人，1972年）。作为这些研究的结果，现在已知磷酸-脂质双层的核磁共振（NMR）谱是非常不同的，这取决于双层是处于多层状态还是处于多层状态。
TA he increased interest in membranestructure and biological transport has stimulated the development of easily prepared model membrane systems, which can be readily manipulated to elucidate some of the physical and chemical properties of biological membranes. In particular there has been much interest in phospholipid bilayers. A simple suspension of bilayer-forming lipidsin water produces a multilamellar structure containing a number of concentric vesicles of various sizes (Bangham and Horne, 1964). Although many structural questions concerning the bilayer phase of these model membranes can be deduced from studies of these multilamellar structures (Papahadjopoulos and Miller, 1967), they are unsuitable for transport studies (Bangham, 1972). Moreover, each multilamellar unit con-tains an unknown number of phospholipid bilayersseparated by an unknown amount of water, whose state of order is un-clear. It is, however, possible to obtain homogeneous phos-phatidylcholine vesicles by prolonged ultrasonic irradiation. These vesicles are closed spheres about 250 A in diameter, each composed of a single continuous lipid bilayer membrane enclosing a volume of aqueous solution (Huang, 1969). Such vesicles have been widely used in recent years as model systems for structural studies of the bimolecular lipid lamellar phase and, in contrast tothe unsonicated preparation of Bangham (1968), have been used in numerous physiochemical and transport studies (Kornberg and McConnell, 1971a, b; Lee et al., 1972; Papahadjopoulos and Watkins, 1967; Bangham, 1972).During the last several years a number of attempts have been made to characterize phospholipid bilayers by nuclear magnetic resonance spectroscopy (Penkett et al., 1968; Finer et al., 1972). As a result of these studies it is now known that the nuclear magnetic resonance(nmr) spectrum of phospho-lipid bilayers is very different depending upon whether the bilayers are in a multilamellar state or whether they are in