1H NMR study of the effect of variable ligand on heme oxygenase electronic and molecular structure
| Autor: | Xuhong Zhang, Yangzhong Liu, Gerd N. La Mar, Li-Hua Ma, Tadashi Yoshida |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
Azides
Cyanides Protein Conformation Ligand Stereochemistry Cyanide Inorganic chemistry Hydrogen Bonding Neisseria meningitidis Ligands Biochemistry Article Inorganic Chemistry Heme oxygenase chemistry.chemical_compound Bacterial Proteins chemistry Heme Oxygenase (Decyclizing) Proton NMR Hemin Azide Metal aquo complex Nuclear Magnetic Resonance Biomolecular Heme Two-dimensional nuclear magnetic resonance spectroscopy |
| Zdroj: | Journal of Inorganic Biochemistry. 103:10-19 |
| ISSN: | 0162-0134 |
| DOI: | 10.1016/j.jinorgbio.2008.08.012 |
| Popis: | Heme oxygenase carries out stereospecific catabolism of protohemin to yield iron, CO and biliverdin. Instability of the physiological oxy complex has necessitated the use of model ligands, of which cyanide and azide are amenable to solution NMR characterization. Since cyanide and azide are contrasting models for bound oxygen, it is of interest to characterize differences in their molecular and/or electronic structures. We report on detailed 2D NMR comparison of the azide and cyanide substrate complexes of heme oxygenase from Neisseria meningitidis, which reveals significant and widespread differences in chemical shifts between the two complexes. To differentiate molecular from electronic structural changes between the two complexes, the anisotropy and orientation of the paramagnetic susceptibility tensor were determined for the azide complex for comparison with those for the cyanide complex. Comparison of the predicted and observed dipolar shifts reveals that shift differences are strongly dominated by differences in electronic structure and do not provide any evidence for detectable differences in molecular structure or hydrogen bonding except in the immediate vicinity of the distal ligand. The readily cleaved C-terminus interacts with the active site and saturation-transfer allows difficult heme assignments in the high-spin aquo complex. |
| Databáze: | OpenAIRE |
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