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          Institute: MPI für bioanorganische Chemie     Collection: MPI für bioanorganische Chemie     Display Documents

ID: 713282.0, MPI für bioanorganische Chemie / MPI für bioanorganische Chemie
Characterization of Oxygen Bridged Manganese Model Complexes Using Multifrequency O17-Hyperfine EPR Spectroscopies and Density Functional Theory
Authors:Rapatskiy, Leonid; Ames, William M.; Perez-Navarro, Montserrat; Savitsky, Anton; Griese, Julia J.; Weyhermüller, Thomas; Shafaat, Hannah S.; Högbom, Martin; Neese, Frank; Pantazis, Dimitrios A.; Cox, Nicholas
Date of Publication (YYYY-MM-DD):2015
Title of Journal:Journal of Physical Chemistry B
Journal Abbrev.:J. Phys. Chem. B
Issue / Number:43
Start Page:13904
End Page:13921
Review Status:Internal review
Audience:Experts Only
Abstract / Description:Multifrequency pulsed EPR data are reported for a series of oxygen bridged (mu-oxo/mu-hydroxo) bimetallic manganese complexes where the oxygen is labeled with the magnetically active isotope O-17 (I = 5/2). Two synthetic complexes and two biological metallocofactors are examined: a planar bis-mu-oxo bridged complex and a bent, bis-mu-oxo-mu-carboxylato bridge complex; the dimanganese catalase, which catalyzes the dismutation of H2O2 to H2O and O-2, and the recently identified manganese/iron cofactor of the R2lox protein, a homologue of the small subunit of the ribonuclotide reductase enzyme (class 1c). High field (W-band) hyperfine EPR spectroscopies are demonstrated to be ideal methods to characterize the O-17 magnetic interactions, allowing a magnetic fingerprint for the bridging oxygen ligand to be developed. It is shown that the mu-oxo bridge motif displays a small positive isotropic hyperfine coupling constant of about +5 to +7 MHz and an anisotropic/dipolar coupling of 9 MHz. In addition, protonation of the bridge is correlated with an increase of the hyperfine coupling constant. Broken symmetry density functional theory is evaluated as a predictive tool for estimating hyperfine coupling of bridging species. Experimental and theoretical results provide a framework for the characterization of the oxygen bridge in Mn metallocofactor systems, including the water oxidizing cofactor of photosystem II, allowing the substrate/solvent interface to be examined throughout its catalytic cycle.
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für bioanorganische Chemie
External Affiliations:[Griese,J.J.; Högbom,M.] Stockholm Univ., Dept.Biochem. & Biophys., SE-10691 Stockholm, Sweden.
Identifiers:ISI:000363994000049 [ID No:1]
ISSN:1520-6106 [ID No:2]
DOI:10.1021/acs.jpcb.5b04614 [ID No:3]
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