Kveder M, Pifat G, Pecar S, Schara M
Ruder Bosković Institute, University of Zagreb, Croatia.
Chem Phys Lipids. 1994 Mar 31;70(1):101-8. doi: 10.1016/0009-3084(94)90052-3.
Three different nitroxides were used to probe either the head group (Tempil stearate) or acyl chain region (Spin labeled cholestane (ChSl) and methyl ester of 5 doxyl palmitate (MeFASL(10,3))) of human plasma low density lipoproteins (LDL) and very low density lipoproteins (VLDL). The ESR data were compared with the simulated spectra which assume rapid anisotropic motion of nitroxide. The results indicate that in the head group region of both LDL and VLDL only the slowing down of the rotational motion occurred when temperature was lowered and the whole region showed up as a unique compartment. On the other hand, the acyl chain region, probed with MeFASL(10,3), behaved as one compartment at physiological temperatures, while at lower temperatures coexistence of fluid and immobilized components were observed. The ESR spectra of lipoproteins labeled with Cholestane showed even higher sensitivity to the mobility constraints. Here, the LDL spectra revealed a drastic immobilization of ChSl axial rotation already at physiological temperatures. The results of these experiments were discussed in terms of core phase transition and/or lipid-protein interactions.
使用三种不同的氮氧化物来探测人血浆低密度脂蛋白（LDL）和极低密度脂蛋白（VLDL）的头部基团（硬脂酸Tempil）或酰基链区域（自旋标记胆甾烷（ChSl）和5 - 多氧棕榈酸甲酯（MeFASL(10,3)））。将电子自旋共振（ESR）数据与假设氮氧化物快速各向异性运动的模拟光谱进行比较。结果表明，在LDL和VLDL的头部基团区域，仅在温度降低时旋转运动减慢，并且整个区域表现为一个独特的隔室。另一方面，用MeFASL(10,3)探测的酰基链区域在生理温度下表现为一个隔室，而在较低温度下观察到流体和固定化成分共存。用胆甾烷标记的脂蛋白的ESR光谱对流动性限制表现出更高的敏感性。在此，LDL光谱显示即使在生理温度下ChSl轴向旋转也会急剧固定。根据核心相变和/或脂质 - 蛋白质相互作用对这些实验结果进行了讨论。
