Characterization of ubisemiquinone radicals in succinate-ubiquinone reductase.
Characterization of ubisemiquinone radicals in succinate-ubiquinone reductase.
复制标题
琥珀酸泛醌还原酶中泛半醌自由基的表征。
DOI：
10.1016/0003-9861(92)90365-4
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发表时间：
1992
影响因子：
3.9
通讯作者：
Yu,CA
中科院分区：
文献类型：
--
作者：
Miki,T;Yu,L;Yu,CA
在纯化的琥珀酸细胞色素c还原酶中很容易检测到噻吩甲酰三氟丙酮敏感和抗霉素不敏感的乌双喹酮自由基(Qs)。当该还原酶被分解为琥珀酸-Q和泛喹酚-细胞色素C还原酶时，在这两种还原酶中都没有检测到Qs。多年来，在纯化的琥珀酸Q还原酶中检测这样一个自由基的难度一直困扰着研究人员。分离的复合体中Q的缺乏是未能检测到Qs的原因。当加入外源Q时，在可控的氧化还原电位下，分离的琥珀酸-Q还原酶中可以很容易地检测到噻吩甲酰三氟丙酮敏感的Q-自由基。当每摩尔黄素加入5摩尔的外源Q时，观察到最大自由基浓度。电子顺磁共振信号的ag值为2.005，线宽为12G。在pH为7.4时，Qs的Ef值为84 mV，半电位为E_1=40 mV，E_2=128 mV。即使在200兆瓦的功率下，QS-RADIO也不会显示出功率饱和。
A thenoyl trifluoroacetone-sensitive and antimycin-insensitive ubisemiquinone radical (Qs) is readily detected in purified succinate-cytochrome c reductase. When this reductase is resolved into succinate-Q and ubiquinol-cytochrome c reductases, Qs was not detected in either reductase. The difficulty in detecting such a radical in purified succinate-Q reductase has puzzled investigators for years. A deficiency of Q in the isolated complex is the reason for the failure to detect Qs. Upon addition of exogenous Q, a thenoyl trifluoroacetone-sensitive Q-radical is readily detectable in isolated succinate-Q reductase under a controlled redox potential. Maximum radical concentration is observed when 5 mol of exogenous Q, per mole of flavin, is added. The radical gives an EPR signal with ag-value of 2.005 and a line-width of 12 G. TheEmof Qs is 84 mV at pH 7.4, with half-potentials ofE1 = 40 mV andE2 = 128 mV. The Qs-radical does not show power saturation, even at 200 mW.