New insights into the catalytic active-site structure of multicopper oxidases

• Komori, Hirofumi

• Sugiyama, Ryosuke

• Kataoka, Kunishige

• Miyazaki, Kentaro

• Higuchi, Yoshiki

• Sakurai, Takeshi

抄録

Structural models determined by X-ray crystallography play a central role in understanding the catalytic mechanism of enzymes. However, X-ray radiation generates hydrated electrons that can cause significant damage to the active sites of metalloenzymes. In the present study, crystal structures of the multicopper oxidases (MCOs) CueO from Escherichia coli and laccase from a metagenome were determined. Diffraction data were obtained from a single crystal under low to high X-ray dose conditions. At low levels of X-ray exposure, unambiguous electron density for an O atom was observed inside the trinuclear copper centre (TNC) in both MCOs. The gradual reduction of copper by hydrated electrons monitored by measurement of the Cu K-edge X-ray absorption spectra led to the disappearance of the electron density for the O atom. In addition, the size of the copper triangle was enlarged by a two-step shift in the location of the type III coppers owing to reduction. Further, binding of O2 to the TNC after its full reduction was observed in the case of the laccase. Based on these novel structural findings, the diverse resting structures of the MCOs and their four-electron O2-reduction process are discussed. © 2014 International Union of Crystallography.

収録刊行物

• Acta Crystallographica Section D: Biological Crystallography

  Acta Crystallographica Section D: Biological Crystallography 70 (3), 772-779, 2014-03-01

  International Union of Crystallography

キーワード

• Bioinorganic chemistry
• Enzyme catalysis
• Metalloproteins
• X-ray absorption spectroscopy

詳細情報

• CRID: 1050845760872567296
• NII論文ID: 120005451980
• NII書誌ID: AA12097672
• ISSN: 13990047
• Web Site: http://hdl.handle.net/2297/38226
• 本文言語コード: en
• 資料種別: journal article
• データソース種別:
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