Extractive solubilization, structural change, and functional conversion of cytochrome c in ionic liquids via crown ether complexation.
Extractive solubilization, structural change, and functional conversion of cytochrome c in ionic liquids via crown ether complexation.
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DOI：
10.1021/ac0612877
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发表时间：
2006-10
影响因子：
7.4
通讯作者：
K. Shimojo;N. Kamiya;F. Tani;H. Naganawa;Y. Naruta;M. Goto
中科院分区：
文献类型：
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作者：
K. Shimojo;N. Kamiya;F. Tani;H. Naganawa;Y. Naruta;M. Goto
本文报道了双环己烯-18-冠-6离子液体（DCH18C6）对血红素蛋白水溶液的萃取行为，以及离子液体中溶解的细胞色素c （Cyt-c）的结构-功能关系。我们发现DCH18C6能够通过超分子络合将富含赖氨酸的蛋白质转移到il中。IL的疏水性和官能团对蛋白质的分配有很大的影响，含有DCH18C6的羟基IL能够定量分配Cyt-c。另一方面，使用传统有机溶剂的蛋白质转移可以忽略不计。紫外-可见、CD和共振拉曼光谱表征表明，IL中Cyt-c- dch18c6络合物血红素基团中的第六配体Met 80被肽链上的其他氨基酸残基取代，IL中诱导了非天然的六坐标低自旋铁血红素结构。触发Cyt-c从电子转移蛋白到过氧化物酶的功能性转化。与天然Cyt-c相比，IL中的Cyt-c- dch18c6复合物提供了非常高的过氧化物酶活性，这是因为它增强了对H2O2的亲和力。
This article reports on the extraction behavior of heme proteins from an aqueous phase into ionic liquids (ILs) with dicyclohexano-18-crown-6 (DCH18C6), and the structure-function relationship of cytochrome c (Cyt-c) dissolved in ILs. We have found that DCH18C6 enables transfer of Lys-rich proteins into ILs via supramolecular complexation. The hydrophobicity and functional groups of ILs have a great influence on protein partitioning, and a hydroxyl group-containing IL with DCH18C6 is capable of the quantitative partitioning of Cyt-c. On the other hand, protein transfer using conventional organic solvents is negligibly small. UV-visible, CD, and resonance Raman spectroscopic characterizations indicate that the sixth ligand Met 80 in the heme group of the Cyt-c-DCH18C6 complex in IL is replaced by other amino acid residues of the peptide chain and that a non-natural, six-coordinate, low-spin ferric heme structure is induced in IL. Solubilization of Cyt-c in IL causes the environmental change of the heme vicinity of Cyt-c, which triggers the functional conversion of Cyt-c from an electron-transfer protein to peroxidase. The Cyt-c-DCH18C6 complex in IL provides remarkably high peroxidase activity compared with native Cyt-c, because of enhancement of the affinity for H2O2.