Hayakawa Tomohiro, Hirano Yoshinori, Makino Asami, Michaud Sabine, Lagarde Michel, Pageaux Jean-François, Doutheau Alain, Ito Kazuki, Fujisawa Tetsuro, Takahashi Hiroshi, Kobayashi Toshihide
Lipid Biology Laboratory, RIKEN (Institute of Physical and Chemical Research), 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan.
Biochemistry. 2006 Aug 1;45(30):9198-209. doi: 10.1021/bi060722o.
Bis(monoacylglycero)phosphate (BMP) reveals an unusual sn-1,sn-1' stereoconfiguration of glycerophosphate. We synthesized sn-(3-myristoyl-2-hydroxy)glycerol-1-phospho-sn-1'-(3'-myristoyl-2'-hydroxy)glycerol (1,1'-DMBMP) and characterized the thermotropic phase behavior and membrane structure, in comparison with those of the corresponding sn-3:sn-1' stereoisomer (3,1'-DMBMP), by means of differential scanning calorimetry (DSC), small- and wide-angle X-ray scattering (SAXS and WAXS, respectively), pressure-area (pi-A) isotherms, epifluorescence microscopy of monolayers, and molecular dynamics (MD) simulations. In DSC, these lipids exhibited weakly energetic broad peaks with an onset temperature of 9 degrees C for 1,1'-DMBMP and 18 degrees C for 3,1'-DMBMP. In addition, a highly cooperative, strongly energetic transition peak was observed at approximately 40 degrees C for 1,1'-DMBMP and approximately 42 degrees C for 3,1'-DMBMP. These results are supported by the observation that 1,1'-DMBMP exhibited a larger phase transition pressure (pi(c)) than 3,1'-DMBMP. Small- and wide-angle X-ray scattering measurements identified these small and large energetic transitions as a quasi-crystalline (L(c1))-quasi-crystalline with different tilt angle (L(c2)) phase transition and an L(c2)-L(alpha) main phase transition, respectively. X-ray measurements also revealed that these DMBMPs undergo an unbinding at the main phase transition temperature. The MD simulations estimated stronger hydrogen bonding formation in the 3,1'-DMBMP membrane than in 1,1'-DMBMP, supporting the experimental data.
双（单酰甘油）磷酸酯（BMP）呈现出甘油磷酸酯不寻常的sn-1，sn-1'立体构型。我们合成了sn-（3-肉豆蔻酰基-2-羟基）甘油-1-磷酸-sn-1'-（3'-肉豆蔻酰基-2'-羟基）甘油（1,1'-DMBMP），并通过差示扫描量热法（DSC）、小角和广角X射线散射（分别为SAXS和WAXS）、压力-面积（π-A）等温线、单层的落射荧光显微镜以及分子动力学（MD）模拟，与相应的sn-3:sn-1'立体异构体（3,1'-DMBMP）相比，对其热致相行为和膜结构进行了表征。在DSC中，这些脂质表现出能量较弱的宽峰，1,1'-DMBMP的起始温度为9℃，3,1'-DMBMP的起始温度为18℃。此外，在约40℃观察到1,1'-DMBMP有一个高度协同、能量较强的转变峰，在约42℃观察到3,1'-DMBMP有一个类似的峰。1,1'-DMBMP表现出比3,1'-DMBMP更大的相变压力（πc），这一观察结果支持了上述结果。小角和广角X射线散射测量分别将这些小的和大的能量转变确定为准晶态（Lc1）-具有不同倾斜角的准晶态（Lc2）相变以及Lc2-Lα主相变。X射线测量还表明，这些DMBMP在主相变温度下会发生解聚。MD模拟估计3,1'-DMBMP膜中形成的氢键比1,1'-DMBMP中的更强，这支持了实验数据。
