Impedance spectroscopy of bacterial membranes: coenzyme-Q diffusion in a finite diffusion layer.
Impedance spectroscopy of bacterial membranes: coenzyme-Q diffusion in a finite diffusion layer.
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DOI：
10.1021/ac8015856
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发表时间：
2008-12-01
影响因子：
7.4
通讯作者：
Bushby, Richard J.
中科院分区：
文献类型：
--
作者：
Jeuken, Lars J. C.;Weiss, Sophie A.;Henderson, Peter J. F.;Evans, Stephen D.;Bushby, Richard J.
过度表达泛醇氧化酶细胞色素 bo3 (cbo3) 的大肠杆菌内膜以平面结构连接到金电极上。通过天然泛醇-8 或添加的泛醇-10 实现电子转移到 cbo3，并使用阻抗谱来表征系留膜系统中泛醇/泛醌的扩散特性。在覆盖电势窗口的不同直流电势下获得光谱，其中cbo3的伏安催化波是可见的。将这些光谱与添加 cbo3 的有效抑制剂氰化物后获得的光谱进行比较，并使用派生的等效电路分析阻抗的差异，该等效电路类似于开放式有限长度扩散 (OFLD) 或有限 Warburg 电路，但修改了边界条件以考虑泛醇再氧化受到酶活性限制的事实。对系留膜系统的阻抗谱的分析给出了与使用循环伏安法获得的值一致的动力学参数。重要的是，泛醌的扩散速率（10−13 - 10−12 cm2/s）被发现比可接受的横向扩散值（10−8 - 10−7 cm2/s）低几个数量级。假设该结果代表醌穿过膜的垂直扩散，对应于 0.05 至 1 秒之间的“翻转”时间。
The inner membrane of Escherichia coli, over-expressing an ubiquinol oxidase, cytochrome bo3 (cbo3), was tethered in a planar configuration to a gold electrode. Electron transfer to cbo3 was achieved via native ubiquinol-8 or added ubiquinol-10 and impedance spectroscopy was used to characterise the diffusion properties of the ubiquinol/ubiquinone in the tethered membrane system. Spectra were obtained at varying DC potentials covering the potential window in which the voltammetric catalytic wave of cbo3 is visible. These spectra were compared to those obtained after addition of a potent inhibitor of cbo3, cyanide, and the difference in impedance was analysed using a derived equivalent circuit, which is similar to that of Open Finite-Length Diffusion (OFLD) or the finite Warburg circuit, but with the boundary conditions modified to account for the fact that ubiquinol reoxidation is limited by enzyme activity. Analysis of the impedance spectra of the tethered membrane system gave kinetic parameters that are consistent with values obtained using cyclic voltammetry. Importantly, the diffusion rate of ubiquinone (10−13 - 10−12 cm2/s) was found to be orders of magnitude lower than accepted values for lateral diffusion (10−8 - 10−7 cm2/s). It is hypothesised that this result represent perpendicular diffusion of quinone across the membrane, corresponding to a ‘flip’ time between 0.05 and 1 s.
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DOI：
10.1016/s0005-2728(05)80136-7
发表时间：
1991-07-05
期刊：
BIOCHIMICA ET BIOPHYSICA ACTA
影响因子：
--
作者：
CHAZOTTE, B;WU, ES;HACKENBROCK, CR
通讯作者：
HACKENBROCK, CR
影响因子：
3.4
作者：
BLACKWELL, MF;GOUNARIS, K;BARBER, J
通讯作者：
BARBER, J
影响因子：
3.4
作者：
Jeuken, Lars J. C.
通讯作者：
Jeuken, Lars J. C.
影响因子：
4.3
作者：
Hauss, T;Dante, S;Dencher, NA
通讯作者：
Dencher, NA
影响因子：
3.5
作者：
Di Bernardo, S;Fato, R;Lenaz, G
通讯作者：
Lenaz, G