Remarkably few enzymes are known to employ a mononuclear manganese ion that undergoes changes in redox state during catalysis. Many questions remain to be answered about the role of substrate binding and/or protein environment in modulating the redox properties of enzyme-bound Mn(II), the nature of the dioxygen species involved in the catalytic mechanism, and how these enzymes acquire Mn(II) given that many other metal ions in the cell form more stable protein complexes. Here, we summarize current knowledge concerning the structure and mechanism of five mononuclear manganese-dependent enzymes: superoxide dismutase, oxalate oxidase (OxOx), oxalate decarboxylase (OxDC), homoprotocatechuate 3,4-dioxygenase, and lipoxygenase (LOX). Spectroscopic measurements and/or computational studies suggest that Mn(III)/Mn(II) are the catalytically active oxidation states of the metal, and the importance of ‘second-shell’ hydrogen bonding interactions with metal ligands has been demonstrated for a number of examples. The ability of these enzymes to modulate the redox properties of the Mn(III)/Mn(II) couple, thereby allowing them to generate substrate-based radicals, appears essential for accessing diverse chemistries of fundamental importance to organisms in all branches of life.
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May 2017
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A His6 motif of the human calprotectin heterodimer with a bound Mn(II) ion. In this issue of Essays in Biochemistry, Neumann et al. look at the how pathogenic Neisseria species exploit host metaloproteins, such as calprotectin, to acquire essential transition metal ions. For further details, see pages 211-223. Image kindly provided by Elizabeth M. Nolan (Massachusetts Institute of Technology). - PDF Icon PDF LinkTable of Contents
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Review Article|
May 09 2017
Biological functions controlled by manganese redox changes in mononuclear Mn-dependent enzymes
Wen Zhu;
Wen Zhu
1School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, U.K.
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Nigel G.J. Richards
1School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, U.K.
Correspondence: Nigel Richards (RichardsN14@cardiff.ac.uk)
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Publisher: Portland Press Ltd
Received:
November 29 2016
Revision Received:
March 05 2017
Accepted:
March 17 2017
Online ISSN: 1744-1358
Print ISSN: 0071-1365
© 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society
2017
Essays Biochem (2017) 61 (2): 259–270.
Article history
Received:
November 29 2016
Revision Received:
March 05 2017
Accepted:
March 17 2017
Citation
Stephen J. Lippard, Jeremy M. Berg, Wen Zhu, Nigel G.J. Richards; Biological functions controlled by manganese redox changes in mononuclear Mn-dependent enzymes. Essays Biochem 9 May 2017; 61 (2): 259–270. doi: https://doi.org/10.1042/EBC20160070
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