LOCATION AND ACTIVITY OF UBIQUINONE-10 AND UBIQUINONE ANALOGS IN MODEL AND BIOLOGICAL-MEMBRANES
LOCATION AND ACTIVITY OF UBIQUINONE-10 AND UBIQUINONE ANALOGS IN MODEL AND BIOLOGICAL-MEMBRANES
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DOI：
10.1021/bi00398a025
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发表时间：
1987-12-01
期刊：
影响因子：
2.9
通讯作者：
WESTERMAN, PW
中科院分区：
文献类型：
--
作者：
CORNELL, BA;KENIRY, MA;WESTERMAN, PW
泛醌10（Q10）的氘代类似物已分散与大肠杆菌的质膜和甜菜根线粒体的内膜。通过固态氘核磁共振（2 H NMR）测量在各种氘化位点处的取向顺序。使用分散在二肉豆蔻酰磷脂酰胆碱（DMPC）和蛋黄卵磷脂和甜菜根线粒体的脂质提取物制备的分散体中的化合物进行了类似的测量。在所有情况下，在浓度低至0.02 mol % Q10/膜脂质时，仅观察到单个未分辨的2 H NMR光谱（通常为1000 Hz半高全宽）。这一结果表明，大多数Q10是在一个移动的环境中，这是物理上分开的双层脂质链的取向约束。相比之下，Q10的短链类似物，其中10个异戊二烯基团已被全氘代十三烷基链取代，显示具有插入双层的有序脂质的典型四极分裂的2 H NMR光谱。在大肠杆菌和线粒体中的NADH氧化酶活性和O2摄取是独立的类似物被纳入膜。因此，尽管它们与膜或其脂质提取物的物理关联存在重大差异，但长链和短链泛醌的电子传递功能是相似的，这表明大部分长链泛醌在电子传递活性中不具有直接功能。生理活性Q10可以仅是总泛醌的一小部分，该部分低于本发明NMR设备的检测水平。然而，我们的研究结果不支持任何模型的Q10电子传递作用，包括插入长的类异戊二烯链在脂质中。
Deuteriated analogues of ubiquinone 10 (Q10) have been dispersed with plasma membranes of Escherichia coli and with the inner membranes of beetroot mitochondria. Orientational order at various deuteriated sites was measured by solid-state deuterium nuclear magnetic resonance (2H NMR). Similar measurements were made, using the compounds dispersed in dimyristoylphosphatidylcholine (DMPC) and egg yolk lecithin and dispersions prepared from the lipid extracts of beetroot mitochondria. In all cases only a single unresolved 2H NMR spectrum (typically 1000-Hz full width at half-height) was observed at concentrations down to 0.02 mol % Q10 per membrane lipid. This result shows that most Q10 is in a mobile environment which is physically separate from the orientational constraints of the bilayer lipid chains. In contrast, a short-chain analogue of Q10, in wihch the 10 isoprene groups have been replaced by a perdeuteriated tridecyl chain, showed 2H NMR spectra with quadrupolar splittings typical of an ordered lipid that is intercalated into the bilayer. The NADH oxidase activity and O2 uptake in Escherichia coli and in mitochondria were independent of which analogue was incorporated into the membrane. Thus, despite the major difference in their physical association with membranes, or their lipid extracts, the electron transport function of the long- and short-chain ubiquinones is similar, suggesting that the bulk of the long-chain ubiquinone does not have a direct function in electron transporting activity. The physiologically active Q10 may only be a small fraction of the total ubiquinone, a fraction that is below the level of detection of the present NMR equipment. However, our results do not support any model of Q10 electron transport action that includes intercalation of the long isoprenoid chain in lipid.