Koenig Bernd W, Gawrisch Klaus
Structural Biology Institute, IBI-2, Research Center Jülich, D-52425 Jülich, Germany.
J Phys Chem B. 2005 Apr 21;109(15):7540-7. doi: 10.1021/jp044980b.
The interaction of ethanol with phospholipids was studied in bicelles at a physiologically relevant ethanol concentration of 20 mM and a lipid content of 14 wt % by high-resolution NMR. Transient association of ethanol with magnetically aligned bicelles imparts a small degree of anisotropy to the solute. This anisotropy allows detection of residual (1)H-(1)H and (1)H-(13)C dipolar couplings, which are superimposed on scalar couplings. Residual (2)H NMR quadrupole splittings of isotope-labeled ethanol were measured as well. The analysis of residual tensorial interactions yielded information on the orientation and motions of ethanol in the membrane-bound state. The fraction of phosphatidylcholine-bound ethanol was determined independently by gas chromatography and NMR. About 4% of ethanol is bound to phosphatidylcholine at a bicelle concentration of 14 wt % at 40 degrees C. Free and bound ethanol are in rapid exchange. The lifetime of ethanol association with phosphatidylcholine membranes is of the order of a few nanoseconds.
在双分子层中，通过高分辨率核磁共振研究了乙醇与磷脂在生理相关乙醇浓度为20 mM和脂质含量为14 wt%条件下的相互作用。乙醇与磁取向双分子层的瞬时缔合赋予溶质一定程度的各向异性。这种各向异性使得能够检测到叠加在标量耦合上的残余（1）H-（1）H和（1）H-（13）C偶极耦合。还测量了同位素标记乙醇的残余（2）H核磁共振四极分裂。对残余张量相互作用的分析产生了关于膜结合状态下乙醇的取向和运动的信息。通过气相色谱和核磁共振独立测定了与磷脂酰胆碱结合的乙醇部分。在40℃下，双分子层浓度为14 wt%时，约4%的乙醇与磷脂酰胆碱结合。游离乙醇和结合乙醇处于快速交换状态。乙醇与磷脂酰胆碱膜缔合的寿命约为几纳秒。
