Localization of coenzyme Q10 in the center of a deuterated lipid membrane by neutron diffraction
Localization of coenzyme Q10 in the center of a deuterated lipid membrane by neutron diffraction
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DOI：
10.1016/j.bbabio.2005.08.007
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发表时间：
2005-11-15
影响因子：
4.3
通讯作者：
Dencher, NA
中科院分区：
文献类型：
--
作者：
Hauss, T;Dante, S;Dencher, NA
醌类（例如，辅酶Q，CoQ（10））最为人所知的是在氧化磷酸化和光合作用期间作为电子和质子的载体。大量的间接物理方法，包括荧光光谱法、电子自旋共振和核磁共振，已经被用来定位脂质膜内的辅酶Q（10）。它们产生了模棱两可、有时甚至相互矛盾的结果。为了寻找泛醌在脂质双层内定位的明确证据，我们采用了中子衍射。辅酶Q（10）被掺入到掺杂有二肉豆蔻酰磷脂酰丝氨酸的全氘代二肉豆蔻酰磷脂酰胆碱的堆叠双层中，所述全氘代二肉豆蔻酰磷脂酰胆碱在天然流体-结晶状态下含有全氘代链。我们的数据显示CoQ（10）位于疏水核心的中心，平行于膜平面，而不是像预期的那样平行于脂质链。这种定位是重要的呼吸复合物之间的氧化还原穿梭的功能，并采取与我们最近的结果，角鲨烷是在双层中心，可以解释为表明，所有的天然聚异戊二烯链位于双层中心。因此，泛醌，除了其自由基清除和其众所周知的作用，在氧化磷酸化作为电子和质子的载体，也可能作为跨膜质子泄漏的抑制剂。(c)2005 Elsevier B. V.保留所有权利。
Quinones (e.g., coenzyme Q, CoQ(10)) are best known as carriers of electrons and protons during oxidative phosphorylation and photosynthesis. A myriad of mostly more indirect physical methods, including fluorescence spectroscopy, electron-spin resonance, and nuclear magnetic resonance, has been used to localize CoQ(10) within lipid membranes. They have yielded equivocal and sometimes contradictory results. Seeking unambiguous evidence for the localization of ubiquinone within lipid bilayers, we have employed neutron diffraction. CoQ(10) was incorporated into stacked bilayers of perdeuterated dimyristoyl phosphatidyl choline doped with dimyristoyl phosphatidyl serine containing perdeuterated chains in the natural fluid-crystalline state. Our data show CoQ(10) at the center of the hydrophobic core parallel to the membrane plane and not, as might be expected, parallel to the lipid chains. This localization is of importance for its function as a redox shuttle between the respiratory complexes and, taken together with our recent result that squalane is in the bilayer center, may be interpreted to show that all natural polyisoprene chains lie in the bilayer center. Thus ubiquinone, in addition to its free radical scavenging and its well-known role in oxidative phosphorylation as a carrier of electrons and protons, might also act as an inhibitor of transmembrane proton leaks. (c) 2005 Elsevier B.V. All rights reserved.