Q-band ENDOR (electron nuclear double resonance) of the high-affinity ubisemiquinone center in cytochrome bo3 from Escherichia coli.
Q-band ENDOR (electron nuclear double resonance) of the high-affinity ubisemiquinone center in cytochrome bo3 from Escherichia coli.
复制标题
大肠杆菌细胞色素 bo3 中高亲和力泛半醌中心的 Q 带 ENDOR（电子核双共振）。
DOI：
10.1021/bi9926835
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发表时间：
2000
期刊：
影响因子：
2.9
通讯作者：
Scholes,CP
中科院分区：
文献类型：
--
作者：
Veselov,AV;Osborne,JP;Gennis,RB;Scholes,CP
利用电子核双共振（ENDOR）技术研究了β_3醌醇氧化酶中与蛋白质结合的、稳定的、高亲和力的泛半醌自由基（QH·-）的电子自旋分布及其与周围环境的相互作用。直到目前的工作，这样的ENDOR研究蛋白质稳定的泛醌中心只做了光合反应中心，其功能是减少泛醇池。相反，QH·-在电子从泛醇池转移到末端氧化酶的耗氧中心的过程中氧化泛醇池。通过与QH·-泛半醌环上不可交换质子的大超精细耦合（>10 MHz），我们证明了QH·-上的电子分布与反应中心的半醌不同。由于泛半醌本身在QH·-和细菌光合反应中心的物理性质几乎相同，这种电子差异显然是局部蛋白质环境的函数。QH·-与这种局部蛋白质环境的相互作用通过可交换的氘ENDOR（暗示与醌的氢键合）和弱质子超精细偶联到局部蛋白质基质而明确显示。
Electron nuclear double resonance (ENDOR) was performed on the protein-bound, stabilized, high-affinity ubisemiquinone radical, QH•-, ofbo3quinol oxidase to determine its electronic spin distribution and to probe its interaction with its surroundings. Until this present work, such ENDOR studies of protein-stabilized ubisemiquinone centers have only been done on photosynthetic reaction centers whose function is to reduce a ubiquinol pool. In contrast, QH•-serves to oxidize a ubiquinol pool in the course of electron transfer from the ubiquinol pool to the oxygen-consuming center of terminalbo3oxidase. As documented by large hyperfine couplings (>10 MHz) to nonexchangeable protons on the QH•-ubisemiquinone ring, we provide evidence for an electronic distribution on QH•-that is different from that of the semiquinones of reaction centers. Since the ubisemiquinone itself is physically nearly identical in both QH•-and the bacterial photosynthetic reaction centers, this electronic difference is evidently a function of the local protein environment. Interaction of QH•-with this local protein environment was explicitly shown by exchangeable deuteron ENDOR that implied hydrogen bonding to the quinone and by weak proton hyperfine couplings to the local protein matrix.