Lateral diffusion of the total polar lipids from Thermoplasma acidophilum in multilamellar liposomes

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• 作者：Jarrell ; Harold C. ; Zukotynski ; Katherine A. ; Sprott ; G. Dennis
• 关键词：Total polar lipid ; Tetraether lipid ; Lateral diffusion ; Membrane viscosity ; ³¹P NMR ; (Thermoplasma acidophilum)
• 刊名：Biochimica et Biophysica Acta (BBA)/Biomembranes
• 出版年：1998
• 出版时间：March 2, 1998
• 年：1998
• 卷：1369
• 期：2
• 页码：259-266
• 全文大小：248 K

文摘

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°C, near the growth temperature, the rate of lateral diffusion, D_L, is comparable to that of diester phospholipids in the L_α liquid crystalline phase, having a value of 2×10⁻⁸ cm²/s. D_L decreases with temperature reaching a value of 8−6×10⁻⁹ cm²/s at 30°C. The activation energy E_a for lateral diffusion is estimated to be 10 kcal/mol (42 kJ/mol). The lateral diffusion rates indicate that the tetraether liposomes have a membrane viscosity at 30°C which is considerably higher than that of diester phospholipids in the liquid crystalline phase.