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Spectroscopic and Crystallographic Evidence for the Role of a Water-Containing H-Bond Network in Oxidase Activity of an Engineered Myoglobin.
- Source :
-
Journal of the American Chemical Society [J Am Chem Soc] 2016 Feb 03; Vol. 138 (4), pp. 1134-7. Date of Electronic Publication: 2016 Jan 20. - Publication Year :
- 2016
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Abstract
- Heme-copper oxidases (HCOs) catalyze efficient reduction of oxygen to water in biological respiration. Despite progress in studying native enzymes and their models, the roles of non-covalent interactions in promoting this activity are still not well understood. Here we report EPR spectroscopic studies of cryoreduced oxy-F33Y-CuBMb, a functional model of HCOs engineered in myoglobin (Mb). We find that cryoreduction at 77 K of the O2-bound form, trapped in the conformation of the parent oxyferrous form, displays a ferric-hydroperoxo EPR signal, in contrast to the cryoreduced oxy-wild-type (WT) Mb, which is unable to deliver a proton and shows a signal from the peroxo-ferric state. Crystallography of oxy-F33Y-CuBMb reveals an extensive H-bond network involving H2O molecules, which is absent from oxy-WTMb. This H-bonding proton-delivery network is the key structural feature that transforms the reversible oxygen-binding protein, WTMb, into F33Y-CuBMb, an oxygen-activating enzyme that reduces O2 to H2O. These results provide direct evidence of the importance of H-bond networks involving H2O in conferring enzymatic activity to a designed protein. Incorporating such extended H-bond networks in designing other metalloenzymes may allow us to confer and fine-tune their enzymatic activities.
Details
- Language :
- English
- ISSN :
- 1520-5126
- Volume :
- 138
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Journal of the American Chemical Society
- Publication Type :
- Academic Journal
- Accession number :
- 26716352
- Full Text :
- https://doi.org/10.1021/jacs.5b12004