Crystallographic and spectroscopic studies of peroxide-derived myoglobin compound II and occurrence of protonated FeIV-O

Hans Petter Hersleth, Takeshi Uchida, Åsmund K. Røhr, Thomas Teschner, Volker Schünemann, Teizo Kitagawa, Alfred X. Trautwein, Carl Henrik Görbitz, K. Kristoffer Andersson*

*Korrespondierende/r Autor/-in für diese Arbeit
45 Zitate (Scopus)


High resolution crystal structures of myoglobin in the pH range 5.2- 8.7 have been used as models for the peroxide-derived compound II intermediates in heme peroxidases and oxygenases. The observed Fe-O bond length (1.86 -1.90 Å) is consistent with that of a single bond. The compound II state of myoglobin in crystals was controlled by single-crystal microspectrophotometry before and after synchrotron data collection. We observe some radiation-induced changes in both compound II (resulting in intermediate H) and in the resting ferric state of myoglobin. These radiation-induced states are quite unstable, and compound II and ferric myoglobin are immediately regenerated through a short heating above the glass transition temperature (<1 s) of the crystals. It is unclear how this influences our compound II structures compared with the unaffected compound II, but some crystallographic data suggest that the influence on the Fe-O bond distance is minimal. Based on our crystallographic and spectroscopic data we suggest that for myoglobin the compound II intermediate consists of an FeIV-O species with a single bond. The presence of FeIV is indicated by a small isomer shift of δ = 0.07 mm/s from Mössbauer spectroscopy. Earlier quantum refinements (crystallographic refinement where the molecular-mechanics potential is replaced by a quantum chemical calculation) and density functional theory calculations suggest that this intermediate H species is protonated.

ZeitschriftJournal of Biological Chemistry
Seiten (von - bis)23372-23386
PublikationsstatusVeröffentlicht - 10.08.2007


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