Spectroscopic analysis of the cytochrome c oxidase-cytochrome c complex: circular dichroism and magnetic circular dichroism measurements reveal change of cytochrome c heme geometry imposed by complex formation.
Spectroscopic analysis of the cytochrome c oxidase-cytochrome c complex: circular dichroism and magnetic circular dichroism measurements reveal change of cytochrome c heme geometry imposed by complex formation.
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细胞色素 c 氧化酶-细胞色素 c 复合物的光谱分析：圆二色性和磁性圆二色性测量揭示了复合物形成引起的细胞色素 c 血红素几何形状的变化。
DOI：
10.1073/pnas.84.19.6687
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发表时间：
1987
影响因子：
11.1
通讯作者：
H. Bosshard
中科院分区：
文献类型：
--
作者：
Christoph Weber;Bruno Michel;H. Bosshard
细胞色素c氧化酶的细胞色素c的结合诱导两种蛋白质的构象变化以及细胞色素c的血红素的电子结构的变化，表明改变血红素c-蛋白质相互作用。这是因为观察到Soret区域中氧化酶-细胞色素c复合物的诱导圆二色性（CD）和磁性圆二色性（MCD）光谱不同于氧化酶加细胞色素c的总光谱。光谱的变化发生在复杂的组成的两个铁或两个亚铁血红素蛋白。差CD和MCD信号以1个血红素c/血红素aa 3的比率饱和。差异光谱是特定的同源复合物。结果被解释为反映识别/结合步骤和电子转移反应之间的直接关系。由细胞色素c氧化酶在细胞色素c中诱导的构象重排由血红素环境的结构重排和可能的血红素铁-甲硫氨酸-80硫轴向键的几何形状的变化组成。这种重排可以通过将血红素c的几何形状调整到铁-和铁细胞色素c之间的状态来降低电子转移的重组自由能。
Binding of cytochrome c to cytochrome c oxidase induces a conformational change in both proteins as well as a change of the electronic structure of the heme of cytochrome c, indicating an altered heme c-protein interaction. This follows from the observation that the induced circular dichroism (CD) and magnetic circular dichroism (MCD) spectra of the oxidase-cytochrome c complex in the Soret region differ from the summed spectra of oxidase plus cytochrome c. Spectral changes occur in the complex composed of either the two ferric or the two ferrous hemoproteins. The difference CD and MCD signals saturate at a ratio of 1 heme c per heme aa3. The difference spectra are specific to the cognate complex. The results are interpreted to reflect a direct relationship between the recognition/binding step and the electron-transfer reaction. The conformational rearrangement induced in cytochrome c by cytochrome c oxidase consists of a structural rearrangement of the heme environment and possibly a change of the geometry of the heme iron-methionine-80 sulfur axial bond. This rearrangement may decrease the reorganizational free energy of electron transfer by adjusting the heme c geometry to a state between that of ferri- and ferrocytochrome c.