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Probing Hydrogen Bonding to Bound Dioxygen in Synthetic Models for Heme Proteins: The Importance of Precise Geometry
Author(s) -
Dube Henry,
Kasumaj Besnik,
Calle Carlos,
Felber Beatrice,
Saito Makoto,
Jeschke Gunnar,
Diederich François
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200802077
Subject(s) - myoglobin , hydrogen bond , chemistry , transition metal dioxygen complex , hemeprotein , adduct , heme , cobalt , crystallography , hydrogen , geometry , stereochemistry , molecule , inorganic chemistry , organic chemistry , mathematics , enzyme
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.