Influence of membrane-spanning alpha-helical peptides on the phase behavior of the dioleoylphosphatidylcholine/water system.
Influence of membrane-spanning alpha-helical peptides on the phase behavior of the dioleoylphosphatidylcholine/water system.
复制标题
跨膜α螺旋肽对二油酰磷脂酰胆碱/水系统相行为的影响。
DOI：
10.1016/s0006-3495(97)78335-8
复制
发表时间：
1997
影响因子：
3.4
通讯作者：
Lindblom,G
中科院分区：
文献类型：
--
作者：
Morein,S;Strandberg,E;Killian,JA;Persson,S;Arvidson,G;Koeppe2nd,RE;Lindblom,G
用~2H、~(31)P-核磁共振波谱和X-射线衍射仪研究了疏水性多肽对二油酰磷脂酰胆碱(DOPC)/水体系相行为的影响，绘制了部分相图。所使用的多肽是HCO-AWW(LA)5WWA-NHCH2CH2OH(WALP16)，这是一种类似于膜蛋白跨膜部分的人造多肽；以及VEYAGIALFFVAAVLTLWSMLQYLSAAR(PGS多肽E)，它与大肠杆菌中假定的膜结合蛋白磷脂酰甘油磷酸合成酶(PGS)的一个跨膜片段相同。圆二色谱表明，这两种多肽在DOPC囊泡中主要是α-螺旋的。WALP_(16)/DOPC/水体系相图中最显著的特征是：1)只有在很低的肽浓度下才能形成单一的片状液晶相(Lα)。2)当水含量较低且肽/脂摩尔比约为1：75时，反六方液晶(H[II])相与Lα相共存，而在水含量过高时，这一相以约1：25的肽/脂摩尔比形成。3)当肽/脂比为>；或=1：6时，单H(II)相是稳定的。此外，PGS多肽E强烈影响相行为，只有在较低的肽浓度(肽/脂摩尔比为1：50)和水浓度为45%(w/w)时，才会出现单一的Lα相。多肽含量越高，Lα相和各向同性相共存。一般来说，各向同性相的比例随着温度和水浓度的增加而增加，在80%(w/w)的水分含量下，只有一个各向同性相在55℃下稳定。因此，在DOPC/水体系中，两种多肽都能够诱导非片层相，尽管结构不同。根据两种多肽的分子结构以及多肽的疏水长度与DOPC双层厚度的匹配关系，讨论了这两个体系的相变、单相区的扩展和相结构。
The effect of solubilized hydrophobic peptides on the phase behavior of dioleoylphosphatidylcholine (DOPC)/water system was studied by 2H- and 31P-NMR spectroscopy and by x-ray diffraction, and partial phase diagrams were constructed. The utilized peptides were HCO-AWW(LA)5WWA-NHCH2CH2OH (WALP16), which is an artificial peptide designed to resemble a transmembrane part of a membrane protein; and VEYAGIALFFVAAVLTLWSMLQYLSAAR (Pgs peptide E), a peptide that is identical to one of the putative transmembrane segments of the membrane-associated protein phosphatidylglycerophosphate synthase (Pgs) in Escherichia coli. Circular dichroism spectroscopy suggests that both peptides are mostly alpha-helical in DOPC vesicles. The most striking features in the phase diagram of the WALP16/DOPC/water system are 1) a single lamellar liquid crystalline (L alpha) phase forms only at very low peptide concentrations. 2) At low water content and above a peptide/lipid molar ratio of approximately 1:75 a reversed hexagonal liquid crystalline (H[II]) phase coexists with an L alpha phase, while in excess water this phase forms at a peptide/lipid molar ratio of approximately 1:25. 3) At peptide/lipid ratios > or=1:6 a single H(II) phase is stable. Also, the Pgs peptide E strongly affects the phase behavior, and a single L alpha phase is only found at low peptide concentrations (peptide/lipid molar ratios <1:50), and water concentrations <45% (w/w). Higher peptide content results in coexistence of L alpha and isotropic phases. Generally, the fraction of the isotropic phase increases with increasing temperature and water concentration, and at 80% (w/w) water content only a single isotropic phase is stable at 55 degrees C. Thus, both peptides were found to be able to induce nonlamellar phases, although different in structure, in the DOPC/water system. The phase transitions, the extensions of the one-phase regions, and the phase structures observed for the two systems are discussed in terms of the molecular structure of the two peptides and the matching between the hydrophobic lengths of the peptides and the bilayer thickness of DOPC.