Probing Hydrogen Bonding to Bound Dioxygen in Synthetic Models for Heme Proteins: The Importance of Precise Geometry

ArticleinChemistry - A European Journal 15(1):125-35 · January 2009with4 Reads
DOI: 10.1002/chem.200802077 · Source: PubMed
Distal hydrogen bonding in natural dioxygen binding proteins is crucial for the discrimination between different potential ligands such as O(2) or CO. In the present study, we probe the chemical requirements for proper distal hydrogen bonding in a series of synthetic model compounds for dioxygen-binding heme proteins. The model compounds 1-Co to 7-Co bear different distal residues. The hydrogen bonding in their corresponding dioxygen adducts is directly measured by pulse EPR spectroscopy. The geometrical requirements for this interaction to take place were found to be narrow and very specific. Only two model complexes, 1-Co and 7-Co, form a hydrogen bond to bound dioxygen, which was characterized in terms of geometry and nature of the bond. The geometry and dipolar nature of this interaction in 1-Co-O(2) is more similar to the one in natural cobalt myoglobin (Co-Mb), making 1-Co the best model compound in the entire series.
    • "GHz. in our laboratories. The proton hyperfine couplings were examined with the main emphasis on distal hydrogen bonding [31,32]. Due to the cross-suppression effect, which hampers the determination of shallow modulation, the proton hyperfine couplings initially could not be detected at X-band [11,33,34]. "
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    B KasumajB KasumajH DubeH DubeN ZölchN Zölch+1more author...[...]
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