Investigation of the Highly Active Manganese Superoxide Dismutase from Saccharomyces cerevisiae

Manganese superoxide dismutase (MnSOD) from different species differs in its efficiency in removing high concentrations of superoxide (O2 −), due to different levels of product inhibition. Human MnSOD exhibits a substantially higher level of product inhibition than the MnSODs from bacteria. In order...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2010-09, Vol.132 (36), p.12525-12527
Main Authors: Barnese, Kevin, Sheng, Yuewei, Stich, Troy A, Gralla, Edith B, Britt, R. David, Cabelli, Diane E, Valentine, Joan Selverstone
Format: Article
Language:English
Subjects:
BACTERIA
BASIC BIOLOGICAL SCIENCES
Biocatalysis
Deinococcus - enzymology
EFFICIENCY
ELECTRON SPIN RESONANCE
Escherichia coli - enzymology
Humans
MANGANESE
Manganese - chemistry
Manganese - metabolism
ORIGIN
Oxidation-Reduction
RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
RADIOLYSIS
REMOVAL
SACCHAROMYCES CEREVISIAE
Saccharomyces cerevisiae - enzymology
SPECTRA
SUPEROXIDE DISMUTASE
Superoxide Dismutase - chemistry
Superoxide Dismutase - metabolism
VALENCE
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Summary:Manganese superoxide dismutase (MnSOD) from different species differs in its efficiency in removing high concentrations of superoxide (O2 −), due to different levels of product inhibition. Human MnSOD exhibits a substantially higher level of product inhibition than the MnSODs from bacteria. In order to investigate the mechanism of product inhibition and whether it is a feature common to eukaryotic MnSODs, we purified MnSOD from Saccharomyces cerevisiae (ScMnSOD). It was a tetramer with 0.6 equiv of Mn per monomer. The catalytic activity of ScMnSOD was investigated by pulse radiolysis and compared with human and two bacterial (Escherichia coli and Deinococcus radiodurans) MnSODs. To our surprise, ScMnSOD most efficiently facilitates removal of high concentrations of O2 − among these MnSODs. The gating value k 2/k 3 that characterizes the level of product inhibition scales as ScMnSOD > D. radiodurans MnSOD > E. coli MnSOD > human MnSOD. While most MnSODs rest as the oxidized form, ScMnSOD was isolated in the Mn2+ oxidation state as revealed by its optical and electron paramagnetic resonance spectra. This finding poses the possibility of elucidating the origin of product inhibition by comparing human MnSOD with ScMnSOD.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja104179r