Ligand energy controls the heme-Fe valence in aqueous myoglobins

Yoshihisa Harada, Munetaka Tagucht, Yoshiharu Miyajima, Takashi Tokushtma, Yuka Horikawa, Ashish Chainani, Yoshitsugu Shiro, Yasunori Senba, Haruhiko Ohashi, Hidetoshi Fukuyama, Shik Shin

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


We use resonant X-ray emission spectroscopy and model calculations to quantify the ligand: heme-Fe energy structure of aqueous myoglobins. For reduced (Fe 2+) and oxidized (Fe 3+) states, the removal or addition of an electron primarily involves charge changes on the ligand-site, and not the Fe-site. The results indicate a finite positive/negative charge-transfer energy A between the heme-Fe 3d and ligand valence electronic states forFe 2+/Fe 3+. Thus, the energy difference between the ligand and Fe 3d states (+Δ or -Δ) determines the charge properties of myoglobins. The study provides a reliable method for characterizing ligand-metal binding of biological systems in solution.

Original languageEnglish
Article number044802
JournalJournal of the Physical Society of Japan
Issue number4
Publication statusPublished - 2009 Apr

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)


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