THE MOBILITY OF A FLUORESCENT UBIQUINONE IN MODEL LIPID-MEMBRANES - RELEVANCE TO MITOCHONDRIAL ELECTRON-TRANSPORT
THE MOBILITY OF A FLUORESCENT UBIQUINONE IN MODEL LIPID-MEMBRANES - RELEVANCE TO MITOCHONDRIAL ELECTRON-TRANSPORT
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DOI：
10.1016/s0005-2728(05)80136-7
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发表时间：
1991-07-05
期刊：
影响因子：
--
通讯作者：
HACKENBROCK, CR
中科院分区：
文献类型：
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作者：
CHAZOTTE, B;WU, ES;HACKENBROCK, CR
的扩散和位置的功能，荧光泛醌分子，NBDHA-Q，确定作为温度的函数，使用显微镜观察，荧光恢复后光漂白和荧光光谱在无蛋白，纯脂质二肉豆蔻酰磷脂酰胆碱和二肉豆蔻酰磷脂酰胆碱/胆固醇多层膜。数据揭示，在液晶膜中（1）泛醌是高度移动的，（2）泛醌以相同的扩散系数（3）均匀地横向扩散。10（-8）cm 2/s（25 ℃）），（3）泛醌和磷脂的扩散系数在磷脂的放热相变时均降低，（4）胆固醇对泛醌和磷脂的扩散系数的影响程度相同，（5）胆固醇诱导侧向相分离，逐渐将泛醌从含胆固醇的结构域中排除。这些数据表明，泛醌不驻留在膜表面或在中间平面的任何可观的时间长度。相反，数据表明，泛醌是高度移动的横向和横向，花费其大部分时间在膜的酰基链区域，其中其横向和横向扩散是有限的横向扩散和横向微粘度梯度的磷脂和其中其横向位置可以受到影响的存在下的胆固醇。此外，基于泛醌，磷脂和线粒体氧化还原复合物的扩散系数的比较，我们假设，没有显着的泛醌池的一部分仍然结合到氧化还原复合物的任何显着的时间长度相对于电子传输的可分辨的荧光恢复后光漂白。
The diffusion and location of a functional, fluorescent ubiquinone molecule, NBDHA-Q, were determined as a function of temperature using microscopic observation, fluorescence recovery after photobleaching and fluorescence spectroscopy in protein-free, pure-lipid dimyristoylphosphatidylcholine and dimyristoylphosphatidylcholine/cholesterol multibilayers. The data reveal that in a liquid-crystalline membrane (1) ubiquinone is highly mobile, (2) ubiquinone uniformly diffuses laterally with the same diffusion coefficient (3 . 10(-8) cm2/s at 25-degrees-C) as the phospholipids in which it resides, (3) the diffusion coefficients of ubiquinone and phospholipid both decrease at the exothermic phase transition of the phospholipid, (4) cholesterol affects the diffusion coefficients of ubiquinone and phospholipids to the same degree, (5) cholesterol induces a lateral phase separation progressively excluding ubiquinone from cholesterol-containing domains. These data suggest that ubiquinone does not reside at the membrane surface or in the mid-plane for any appreciable length of time. Rather, the data indicate that ubiquinone is highly mobile laterally and transversely, spending the majority of its time in the acyl chain region of the membrane, where its lateral and transverse diffusion is limited by the lateral diffusion and the transverse microviscosity gradient of the phospholipids and where its lateral location can be affected by the presence of cholesterol. In addition, based upon a comparison of the diffusion coefficients for ubiquinone, phospholipids and mitochondrial redox complexes, we hypothesize that no significant portion of the ubiquinone pool remains bound to redox complexes for any significant length of time relative to that for electron transport as resolvable by fluorescence recovery after photobleaching.