Structural bases for function in cytochromes c. An interpretation of comparative x-ray and biochemical data.
Structural bases for function in cytochromes c. An interpretation of comparative x-ray and biochemical data.
复制标题
细胞色素功能的结构基础 c．
DOI：
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发表时间：
1973
影响因子：
4.8
通讯作者：
M. Kamen
中科院分区：
文献类型：
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作者：
F. Salemme;J. Kraut;M. Kamen
摘要 比较了红色红螺菌光合细胞色素 c2 和真核线粒体细胞色素 c 的三级结构，以及它们的理化性质和生理氧化还原系统活性的数据。通过比较得出以下观察结果和建议。 1. R. rubrum 细胞色素 c2 不经历真核细胞色素 c 特有的广泛氧化还原相关构象变化，而是在结构上受到两种氧化态构象的限制，总体上与铁细胞色素 c 最为相似。 2.通过检查和比较细胞色素c和c2的表面结构和电荷形貌，很明显它们在正面（即面向血红素缝隙）具有迄今为止最接近的相似性。由于细胞色素 c2 和 41 种真核细胞色素 c 中血红素缝隙周围的许多氨基酸残基的绝对不变性，该特征清楚地表现出来。 3. 提出了真核细胞色素 c 氧化还原的生理机制，其原则上与之前提出的细胞色素 c2 相似（Sa-lemme, F.R., Freer, S.T., Xuong, Ng.H., Alden, R.A., and Kraut, J. (1973) J. Biol. Chem. 248, 3910–3921）。该机制涉及细胞色素 c 分子与其氧化酶和还原酶的前侧相互作用，以及直接向血红素添加电子和从血红素撤回电子，同时伴随现有血红素氧化态的不稳定。
Abstract The tertiary structures of the photosynthetic cytochrome c2 of Rhodospirillum rubrum and eucaryotic mitochondrial cytochrome c are compared, together with data on their physiochemical properties and activities in physiological oxidoreduction systems. The comparison gives rise to the following observations and proposals. 1. R. rubrum cytochrome c2 does not undergo the extensive oxidoreduction-linked conformation change characteristic of eucaryotic cytochromes c, but rather is structurally constrained in a conformation in both oxidation states which is over-all most similar to that of ferrocytochrome c. 2. Upon examination and comparison of the surface structural and charge topography of cytochromes c and c2, it is apparent that they bear by far the closest similarity at their front sides (i.e. facing the heme crevice). This feature manifests itself clearly owing to the absolute invariance of many of the amino acid residues surrounding the perimeter of the heme crevice in both cytochrome c2 and 41 species of eucaryotic cytochrome c. 3. A physiological mechanism for the oxidoreduction of eucaryotic cytochrome c is proposed which is in principle similar to that previously suggested for cytochrome c2 (Sa-lemme, F.R., Freer, S.T., Xuong, Ng.H., Alden, R.A., and Kraut, J. (1973) J. Biol. Chem. 248, 3910–3921). This mechanism involves front side interaction of the cytochrome c molecule with its oxidase and reductase, and direct electron addition to and withdrawal from the heme concomitant with destabilization of the existing heme oxidation state.