Muller J M, van Ginkel G, van Faassen E E
Debye Research Institute, Utrecht, The Netherlands.
Biochemistry. 1995 Mar 7;34(9):3092-101. doi: 10.1021/bi00009a041.
We investigated the effects of the hydrophobic small peptide antibiotic gramicidin A (gA) on the properties of vesicle bilayers in the liquid crystalline state. Time-resolved fluorescence anisotropy experiments were performed with unilamellar vesicles of the lipids DMPC, POPC, DOPC, EGGPC, DLPC, DOPG, and SQDG containing various concentrations of gA in two different conformations using TMA-DPH and DPHPC as fluorescent probes. These analogues of DPH were taken to study the gA induced change in the structural and dynamical properties of the lipid bilayer in different portions of the hydrophobic region. The time-resolved anisotropy data were analyzed using the recently introduced compound motion model [van der Sijs, D. A., et al. (1993) Chem. Phys. Lett. 216, 559; Muller, J. M., et al. (1994) Chem. Phys. 185, 393]. In general, gA raises the order and reduces the rotational diffusion coefficient for the probes in the bilayer. In DOPC vesicles this ordering effect of gA on the bilayer is found to depend on both the conformation of the peptide and the depth in the bilayer at which the order is probed. This significant effect of gA conformation on the lipid order parameter profile suggests that the shape of the gA dimer in the bilayer, which is determined by its conformation, affects the order of the adjacent DOPC lipid acyl chains.
我们研究了疏水性小肽抗生素短杆菌肽A（gA）对液晶态囊泡双层膜性质的影响。使用TMA-DPH和DPHPC作为荧光探针，对含有不同浓度gA的脂质DMPC、POPC、DOPC、EGGPC、DLPC、DOPG和SQDG的单层囊泡进行了时间分辨荧光各向异性实验，这些囊泡中的gA具有两种不同构象。选用这些DPH类似物来研究gA诱导的疏水区域不同部分脂质双层结构和动力学性质的变化。利用最近引入的复合运动模型[van der Sijs, D. A., 等人 (1993) 《化学物理快报》216, 559; Muller, J. M., 等人 (1994) 《化学物理》185, 393]对时间分辨各向异性数据进行了分析。一般来说，gA提高了双层膜中探针的有序度并降低了其旋转扩散系数。在DOPC囊泡中，发现gA对双层膜的这种有序化作用取决于肽的构象以及探测有序度时在双层膜中的深度。gA构象对脂质有序参数分布的这种显著影响表明，双层膜中由其构象决定的gA二聚体形状会影响相邻DOPC脂质酰基链的有序度。
