TY - JOUR
T1 - Two-dimensional HYSCORE spectroscopy of superoxidized manganese catalase
T2 - A model for the oxygen-evolving complex of photosystem II
AU - Coates, Christopher S.
AU - Milikisiyants, Sergey
AU - Chatterjee, Ruchira
AU - Whittaker, Mei M.
AU - Whittaker, James W.
AU - Lakshmi, K. V.
N1 - Publisher Copyright:
© 2015 American Chemical Society.
PY - 2015/4/16
Y1 - 2015/4/16
N2 - The solar water-splitting protein complex, photosystem II (PSII), catalyzes one of the most energetically demanding reactions in Nature by using light energy to drive a catalyst capable of oxidizing water. The water oxidation reaction takes place at the tetra-nuclear manganese calcium-oxo (Mn4Ca-oxo) cluster at the heart of the oxygen-evolving complex (OEC) of PSII. Previous studies have determined the magnetic interactions between the paramagnetic Mn4Ca-oxo cluster and its environment in the S2 state of the OEC. The assignments for the electron-nuclear magnetic interactions that were observed in these studies were facilitated by the use of synthetic dimanganese di-μ-oxo complexes. However, there is an immense need to understand the effects of the protein environment on the coordination geometry of the Mn4Ca-oxo cluster in the OEC of PSII. In the present study, we use a proteinaceous model system to examine the protein ligands that are coordinated to the dimanganese catalytic center of manganese catalase from Lactobacillus plantarum. We utilize two-dimensional hyperfine sublevel correlation (2D HYSCORE) spectroscopy to detect the weak magnetic interactions of the paramagnetic dinuclear manganese catalytic center of superoxidized manganese catalase with the nitrogen and proton atoms of the surrounding protein environment. We obtain a complete set of hyperfine interaction parameters for the protons of a water molecule that is directly coordinated to the dinuclear manganese center. We also obtain a complete set of hyperfine and quadrupolar interaction parameters for two histidine ligands as well as a coordinated azide ligand, in azide-treated superoxidized manganese catalase. On the basis of the values of the hyperfine interaction parameters of the dimanganese model, manganese catalase, and those of the S2 state of the OEC of PSII, for the first time, we discuss the impact of a proteinaceous environment on the coordination geometry of multinuclear manganese clusters.
AB - The solar water-splitting protein complex, photosystem II (PSII), catalyzes one of the most energetically demanding reactions in Nature by using light energy to drive a catalyst capable of oxidizing water. The water oxidation reaction takes place at the tetra-nuclear manganese calcium-oxo (Mn4Ca-oxo) cluster at the heart of the oxygen-evolving complex (OEC) of PSII. Previous studies have determined the magnetic interactions between the paramagnetic Mn4Ca-oxo cluster and its environment in the S2 state of the OEC. The assignments for the electron-nuclear magnetic interactions that were observed in these studies were facilitated by the use of synthetic dimanganese di-μ-oxo complexes. However, there is an immense need to understand the effects of the protein environment on the coordination geometry of the Mn4Ca-oxo cluster in the OEC of PSII. In the present study, we use a proteinaceous model system to examine the protein ligands that are coordinated to the dimanganese catalytic center of manganese catalase from Lactobacillus plantarum. We utilize two-dimensional hyperfine sublevel correlation (2D HYSCORE) spectroscopy to detect the weak magnetic interactions of the paramagnetic dinuclear manganese catalytic center of superoxidized manganese catalase with the nitrogen and proton atoms of the surrounding protein environment. We obtain a complete set of hyperfine interaction parameters for the protons of a water molecule that is directly coordinated to the dinuclear manganese center. We also obtain a complete set of hyperfine and quadrupolar interaction parameters for two histidine ligands as well as a coordinated azide ligand, in azide-treated superoxidized manganese catalase. On the basis of the values of the hyperfine interaction parameters of the dimanganese model, manganese catalase, and those of the S2 state of the OEC of PSII, for the first time, we discuss the impact of a proteinaceous environment on the coordination geometry of multinuclear manganese clusters.
UR - http://www.scopus.com/inward/record.url?scp=84927948921&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84927948921&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcb.5b01602
DO - 10.1021/acs.jpcb.5b01602
M3 - Article
C2 - 25731604
AN - SCOPUS:84927948921
SN - 1520-6106
VL - 119
SP - 4905
EP - 4916
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 15
ER -