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Publication Abstract from PubMed

Heme-copper oxidases (HCOs) catalyze efficient reduction of O2 to water in biological respiration. Despite progress made in studying native enzymes and their models, the roles played by non-covalent interactions in promoting this activity are still not well understood. Herein, we report EPR spectroscopic studies of cryoreduced oxy-F33Y-CuBMb, a functional model of HCOs engineered in myoglobin (Mb). We find that the cryoreduction at 77K 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 Mb (WTMb), which is unable to deliver a proton and shows a signal from the peroxo-ferric state. Crystallography of oxy-F33Y-CuBMb reveals an extensive hydrogen-bonding network involving water molecules, which is absent from oxy-WTMb. This H-bonding, proton-delivery network is the key structural feature that has transformed the reversible oxygen-binding protein, WTMb, into F33Y-CuBMb, an oxygen-activating enzyme that reduces oxygen to water. These results provide direct evidence of the importance of H-bonding networks involving water in conferring enzymatic activity to a designed metalloenzyme. Incorporating such extended H-bonding networks in the design of other metalloenzymes may allow conferring and fine-tuning their enzymatic activities.

Spectroscopic and crystallographic evidence for the role of a water-containing hydrogen bonding network in oxidase activity of an engineered myoglobin.,Petrik ID, Davydov R, Ross M, Zhao X, Hoffman B, Lu Y J Am Chem Soc. 2015 Dec 30. PMID:26716352^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.