Cytochrome c-crown ether complexes as supramolecular catalysts: cold-active synzymes for asymmetric sulfoxide oxidation in methanol.
Cytochrome c-crown ether complexes as supramolecular catalysts: cold-active synzymes for asymmetric sulfoxide oxidation in methanol.
复制标题
DOI：
10.1021/ic0486567
复制
发表时间：
2005-01
影响因子：
4.6
通讯作者：
Atsuko Suzumura;D. Paul;H. Sugimoto;S. Shinoda;R. R. Julian-R.;J. Beauchamp;J. Teraoka;H. Tsukube
中科院分区：
文献类型：
--
作者：
Atsuko Suzumura;D. Paul;H. Sugimoto;S. Shinoda;R. R. Julian-R.;J. Beauchamp;J. Teraoka;H. Tsukube
一系列具有18冠-6衍生物的细胞色素c蛋白的超分子复合物在H2O2氧化外消旋亚砜过程中表现为冷活性合酶。这种有趣的行为与天然功能形成对比，在天然功能中，所使用的蛋白质充当电子转移载体。质。紫外，CD和拉曼光谱表征表明，4或5个18冠6分子与细胞色素c表面强结合，并且在甲醇中诱导了非天然的低自旋六配位血红素结构。值得注意的是，冠醚络合可以将无催化活性的生物形式转化为具有催化活性的人工形式。马心、鸽子胸脯和酵母细胞色素c在冠醚络合作用下都能立体选择性氧化甲基甲基亚砜和相关亚砜的(S)-异构体。这些超分子催化剂在-40℃时对h2o2依赖性亚砜氧化反应表现出最高的效率和对映体选择性，而血红素部分的氧化分解主要发生在室温下。所研究的亚砜的氧化反应活性明显与其S=O键的空间约束和电化学氧化势有关。在细胞色素c络合物中，酵母细胞色素c表现出最低的催化活性和降解活性。它具有显著不同的蛋白质序列，表明冠醚络合有效地激活血红素配位，但可能额外改变天然骨架结构。细胞色素c蛋白、18冠-6受体和外部环境的适当结合可以成功地产生具有非生物反应性的“基于蛋白质的超分子催化剂”。
A series of supramolecular complexes of various cytochrome c proteins with 18-crown-6 derivatives behave as cold-active synzymes in the H2O2 oxidation of racemic sulfoxides. This interesting behavior contrasts with native functionality, where the employed proteins act as electron transfer carriers. ESI-MS. UV, CD, and Raman spectroscopic characterizations reveal that four or five 18-crown-6 molecules strongly bind to the surface of the cytochrome c and also that nonnatural low-spin hexacoordinate heme structures are induced in methanol. Significantly, crown ether complexation can convert catalytically inactive biological forms to catalytically active artificial forms. Horse heart, pigeon breast, and yeast cytochromes c all stereoselectively oxidize (S)-isomers of methyl tolyl sulfoxide and related sulfoxides upon crown ether complexation. These supramolecular catalysts show the highest efficiency and enantiomer selectivity at -40 degrees C in the H202-dependent sulfoxide oxidation, while oxidative decomposition of the heme moieties predominantly occurs at room temperature. The oxidation reactivity of the employed sulfoxides is apparently related to steric constraints and electrochemical oxidation potentials of their S=O bonds. Among the cytochrome c complexes, yeast cytochrome c demonstrates the lowest catalytic activity and degradation reactivity. It has a significantly different protein sequence, suggesting that crown ether complexation effectively activates heme coordination but may additionally alter the native backbone structure. The proper combination of cytochrome c proteins, 18-crown-6 receptors, and external circumstances can be used to successfully generate "protein-based supramolecular catalysts" exhibiting nonbiological reactivities.