2v1h
CRYSTAL STRUCTURE OF RADIATION-INDUCED METMYOGLOBIN- AQUA FERROUS MYOGLOBIN AT PH 5.2
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OverviewOverview
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 A) 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 Fe(IV)-O species with a single bond. The presence of Fe(IV) is indicated by a small isomer shift of delta = 0.07 mm/s from Mossbauer 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.
About this StructureAbout this Structure
2V1H is a Single protein structure of sequence from Equus caballus with , and as ligands. Known structural/functional Sites: , , , , , and . Full crystallographic information is available from OCA.
ReferenceReference
Crystallographic and spectroscopic studies of peroxide-derived myoglobin compound II and occurrence of protonated FeIV O., Hersleth HP, Uchida T, Rohr AK, Teschner T, Schunemann V, Kitagawa T, Trautwein AX, Gorbitz CH, Andersson KK, J Biol Chem. 2007 Aug 10;282(32):23372-86. Epub 2007 Jun 12. PMID:17565988
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