Cherezov V, Siegel D P, Shaw W, Burgess S W, Caffrey M
Biochemistry, Biophysics and Chemistry, The Ohio State University, 100W 18th Ave., Columbus, OH 43210, USA.
J Membr Biol. 2003 Oct 1;195(3):165-82. doi: 10.1007/s00232-003-0617-z.
The mechanism of the lamellar/inverted cubic (QII) phase transition is related to that of membrane fusion in lipid systems. N-Monomethylated dioleoylphosphatidylethanolamine (DOPE-Me) exhibits this transition and is commonly used to investigate the effects of exogenous substances, such as viral fusion peptides, on the mechanism of membrane fusion. We studied DOPE-Me phase behavior as a first step in evaluating the effects of membrane-spanning peptides on inverted phase formation and membrane fusion. These measurements show that: a) the onset temperatures for QII and inverted hexagonal (HII) phase formation both are temperature scan rate-dependent; b) longer pre-incubation times at low temperature and lower temperature scan rates favor formation of the QII phase; and c) in temperature-jump experiments between 61 and 65 degrees C, the meta-stable HII phase forms initially, and disappears slowly while the QII phase develops. These observations are rationalized in the context of a mechanism for both the lamellar/non-lamellar phase transition and the related process of membrane fusion.
片层/反立方（QII）相转变的机制与脂质体系中的膜融合机制相关。N-单甲基化二油酰磷脂酰乙醇胺（DOPE-Me）呈现这种转变，并且通常用于研究外源性物质（如病毒融合肽）对膜融合机制的影响。作为评估跨膜肽对反相形成和膜融合影响的第一步，我们研究了DOPE-Me的相行为。这些测量结果表明：a）QII相和反六角（HII）相形成的起始温度均与温度扫描速率相关；b）在低温下较长的预孵育时间和较低的温度扫描速率有利于QII相的形成；c）在61至65摄氏度之间的温度跃变实验中，亚稳HII相最初形成，并在QII相发展时缓慢消失。这些观察结果在片层/非片层相转变及相关膜融合过程的机制背景下得到了合理的解释。
