Solution 1h NMR characterization of equilibrium heme orientational disorder with functional consequences in mouse neuroglobin |
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Authors: | Du Weihong Syvitski Ray Dewilde Sylvia Moens Luc La Mar Gerd N |
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Institution: | Department of Chemistry, University of California-Davis, Davis, CA 95616, USA. |
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Abstract: | The solution 1H NMR spectrum of oxidized (met) mouse neuroglobin, metNgb, demonstrates that it is low-spin and hexacoordinate with strong spectral similarities to ferricytochrome b5. The axial ligands are identified as His(F8) and His(E7), with the latter exhibiting an unstrained Fe-His bond. The presence of two sets of resonances is shown to arise from equilibrium heme orientational isomers ( approximately 2:1). The ligation of cyanide is shown to be extraordinarily slow with a factor approximately 2 difference in rate for the two heme orientations. Not only is Ngb the first mamalian globin with equilibrium heme disorder, but the disorder also has additional functional consequences. |
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