Jarrell H C, Zukotynski K A, Sprott G D
Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ont., Canada.
Biochim Biophys Acta. 1998 Mar 2;1369(2):259-66. doi: 10.1016/s0005-2736(97)00228-9.
31P NMR lineshapes of multilamellar liposomes composed mostly of a bilayer-spanning tetraether lipid are consistent with rapid axially symmetric motion about the bilayer normal. The residual chemical shift anisotropy of 36 ppm is comparable to that seen for diacylphosphatidylglycerol systems and suggests comparable headgroup motion. The lateral diffusion rates for Thermoplasma acidophilum total polar lipids in mutilamellar liposomes was measured by two dimensional exchange NMR as a function of temperature. At 55 degrees C, near the growth temperature, the rate of lateral diffusion, DL, is comparable to that of diester phospholipids in the Lalpha liquid crystalline phase, having a value of 2 x 10(-8) cm2/s. DL decreases with temperature reaching a value of 8-6 x 10(-9) cm2/s at 30 degrees C. The activation energy Ea for lateral diffusion is estimated to be 10 kcal/mol (approximately 42 kJ/mol). The lateral diffusion rates indicate that the tetraether liposomes have a membrane viscosity at 30 degrees C which is considerably higher than that of diester phospholipids in the liquid crystalline phase.
主要由跨双层四醚脂质组成的多层脂质体的³¹P NMR线形与围绕双层法线的快速轴对称运动一致。36 ppm的剩余化学位移各向异性与二酰基磷脂酰甘油系统的相当，表明头基运动相当。通过二维交换NMR测量嗜热栖热菌总极性脂质在多层脂质体中的横向扩散速率与温度的函数关系。在接近生长温度的55℃时，横向扩散速率DL与Lα液晶相中的二酯磷脂相当，值为2×10⁻⁸ cm²/s。DL随温度降低，在30℃时达到8 - 6×10⁻⁹ cm²/s。横向扩散的活化能Ea估计为10 kcal/mol（约42 kJ/mol）。横向扩散速率表明，四醚脂质体在30℃时的膜粘度远高于液晶相中的二酯磷脂。
