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Title
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Unusual flexibility of distal and proximal histidine residues in the haem pocket of **Drosophila melanogaster** haemoglobin
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Author
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Abstract
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| Several pH-dependent low-spin ferric haem forms are identified in a frozen solution of the ferric 121CysSer mutant of Drosophila melanogaster haemoglobin (DmHb1*) using electron paramagnetic resonance (EPR) techniques. Different forms with EPR parameters typical of bis-histidine coordinated haem iron centers were observed. Strong pH-dependent changes in the EPR signatures were observed related to changes in the haem pocket. The pulsed EPR data indicate that both the distal and proximal histidine exhibit a large libration around the FeNHis axis. The resonance Raman spectra of the CO-ligated ferrous form of Drosophila melanogaster haemoglobin are typical of an open conformation, with little stabilization of the CO ligand by the surrounding amino-acid residues. The EPR data of the cyanide-ligated ferric DmHb1* indicates a close similarity with cyanide-ligated ferric myoglobin. The structural characteristics of DmHb1* are found to clearly differ from those of other bis-histidine-coordinated globins. |
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Language
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English
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Source (journal)
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Metallomics / Royal Society of Chemistry [London] - Cambridge
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Publication
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Cambridge
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2009
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ISSN
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1756-5901
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Volume/pages
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1
:3
(2009)
, p. 256-264
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ISI
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000269034300009
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Full text (Publisher's DOI)
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