Unknown

Dataset Information

0

Experimental and computational X-ray emission spectroscopy as a direct probe of protonation states in oxo-bridged Mn(IV) dimers relevant to redox-active metalloproteins.


ABSTRACT: The protonation state of oxo bridges in nature is of profound importance for a variety of enzymes, including the Mn4CaO5 cluster of photosystem II and the Mn2O2 cluster in Mn catalase. A set of dinuclear bis-?-oxo-bridged Mn(IV) complexes in different protonation states was studied by K? emission spectroscopy to form the foundation for unraveling the protonation states in the native complex. The valence-to-core regions (valence-to-core XES) of the spectra show significant changes in intensity and peak position upon protonation. DFT calculations were performed to simulate the valence-to-core XES spectra and to assign the spectral features to specific transitions. The K?(2,5) peaks arise primarily from the ligand 2p to Mn 1s transitions, with a characteristic low energy shoulder appearing upon oxo-bridge protonation. The satellite K?" peak provides a more direct signature of the protonation state change, since the transitions originating from the 2s orbitals of protonated and unprotonated ?-oxo bridges dominate this spectral region. The energies of the K?" features differ by ~3 eV and thus are well resolved in the experimental spectra. Additionally, our work explores the chemical resolution limits of the method, namely, whether a mixed (?-O)(?-OH2) motif can be distinguished from a symmetric (?-OH)2 one. The results reported here highlight the sensitivity of K? valence-to-core XES to single protonation state changes of bridging ligands, and form the basis for further studies of oxo-bridged polymetallic complexes and metalloenzyme active sites. In a complementary paper, the results from X-ray absorption spectroscopy of the same Mn(IV) dimer series are discussed.

SUBMITTER: Lassalle-Kaiser B 

PROVIDER: S-EPMC3867288 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature

altmetric image

Publications

Experimental and computational X-ray emission spectroscopy as a direct probe of protonation states in oxo-bridged Mn(IV) dimers relevant to redox-active metalloproteins.

Lassalle-Kaiser Benedikt B   Boron Thaddeus T TT   Krewald Vera V   Kern Jan J   Beckwith Martha A MA   Delgado-Jaime Mario U MU   Schroeder Henning H   Alonso-Mori Roberto R   Nordlund Dennis D   Weng Tsu-Chien TC   Sokaras Dimosthenis D   Neese Frank F   Bergmann Uwe U   Yachandra Vittal K VK   DeBeer Serena S   Pecoraro Vincent L VL   Yano Junko J  

Inorganic chemistry 20131025 22


The protonation state of oxo bridges in nature is of profound importance for a variety of enzymes, including the Mn4CaO5 cluster of photosystem II and the Mn2O2 cluster in Mn catalase. A set of dinuclear bis-μ-oxo-bridged Mn(IV) complexes in different protonation states was studied by Kβ emission spectroscopy to form the foundation for unraveling the protonation states in the native complex. The valence-to-core regions (valence-to-core XES) of the spectra show significant changes in intensity an  ...[more]

Similar Datasets

| S-EPMC3911776 | biostudies-literature
| S-EPMC6891804 | biostudies-literature
| S-EPMC7499863 | biostudies-literature
| S-EPMC8456941 | biostudies-literature
| S-EPMC7388070 | biostudies-literature
| S-EPMC6195362 | biostudies-literature
| S-EPMC5518598 | biostudies-literature
| S-EPMC4118035 | biostudies-literature
| S-EPMC2787892 | biostudies-literature
| S-EPMC7567882 | biostudies-literature