Characterization of Non-Native Heme Coordination Structures Emerging upon Guanidine Hydrochloric Acid-Induced Unfolding of <i>Pseudomonas aeruginosa</i> Ferricytochrome <i>c</i>551

• Hulin Tai

  Department of Chemistry, University of Tsukuba

• Shigenori Nagatomo

  Department of Chemistry, University of Tsukuba

• Hajime Mita

  Department of Chemistry, University of Tsukuba

• Yoshihiro Sambongi

  Graduate School of Biosphere Science, Hiroshima University

• Yasuhiko Yamamoto

  Department of Chemistry, University of Tsukuba

Abstract

The non-native heme coordination structures emerging upon guanidine hydrochloric acid (GdnHCl)-induced unfolding of Pseudomonas aeruginosa ferricytochrome c551 were characterized by absorption, circular dichroism, paramagnetic NMR, and resonance Raman spectroscopy. Hexacoordinated high-spin ferriheme bearing axial His and H2O ligands, and pentacoordinated high-spin ferriheme with an axial His ligand were identified in the presence of GdnHCl concentrations ≥ 1.5 M (M = mol dm−3). These non-native species were rapidly interconverted to each other through cleavage/formation of the Fe–H2O coordination bond, and were also in dynamic equilibrium, at a rate of &lt; 2 × 104 s−1, with the native species. Thus, the present study demonstrated the presence of dynamic equilibrium through cleavage/formation of a Fe–H2O coordination bond in an unfolding intermediate. These results provide a deeper insight into structure transitions of the heme active site upon folding and unfolding of cytochrome c.

Journal

• Bulletin of the Chemical Society of Japan

  Bulletin of the Chemical Society of Japan 78 (11), 2019-2025, 2005-10-31

  Oxford University Press (OUP)

Keywords

• General Chemistry

Details

• CRID: 1360565169058481024
• NII Article ID: 130004058601
• DOI: 10.1246/bcsj.78.2019
• ISSN: 13480634
• ISSN: 00092673
• Web Site: https://academic.oup.com/bcsj/article-pdf/78/11/2019/56266676/bcsj.78.2019.pdf
• Data Source:
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  • CiNii Articles