Extractive solubilization, structural change, and functional conversion of cytochrome c in ionic liquids via crown ether complexation

Kojiro Shimojo, Noriho Kamiya, Fumito Tani, Hirochika Naganawa, Yoshinori Naruta, Masahiro Goto

Research output: Contribution to journalArticle

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Abstract

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.

Original languageEnglish
Pages (from-to)7735-7742
Number of pages8
JournalAnalytical Chemistry
Volume78
Issue number22
DOIs
Publication statusPublished - Nov 15 2006

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Crown Ethers
Ionic Liquids
Cytochromes c
Complexation
Heme
Peroxidase
Proteins
Cytochrome c Group
Hemeproteins
Hydrophobicity
Hydroxyl Radical
Organic solvents
Functional groups
dicyclohexyl-18-crown-6
Ligands
Amino Acids
Peptides

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry

Cite this

Extractive solubilization, structural change, and functional conversion of cytochrome c in ionic liquids via crown ether complexation. / Shimojo, Kojiro; Kamiya, Noriho; Tani, Fumito; Naganawa, Hirochika; Naruta, Yoshinori; Goto, Masahiro.

In: Analytical Chemistry, Vol. 78, No. 22, 15.11.2006, p. 7735-7742.

Research output: Contribution to journalArticle

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