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Special Issue "25th Anniversary of Molecules - Featuring Element 25: Manganese and/or Other Metals"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Molecular Structure".

Deadline for manuscript submissions: 31 December 2021.

Special Issue Editors

Prof. Dr. Rudy J. Richardson
E-Mail Website
Guest Editor
Molecular Simulations Laboratory, EHS/Toxicology, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109-2029, USA
Interests: computational/predictive toxicology (including molecular modeling; classical, sequential, inverse, ensemble, and covalent docking; molecular dynamics simulations; cheminformatics; pharmacophore/toxicophore mapping; QSAR; and pathway analysis); ligand–receptor interactions (active and allosteric sites); protein structure prediction (threading, homology modeling, and in silico mutagenesis); protein engineering; drug discovery and development; adverse side effects of drugs; biomarkers and biosensors; counterterrorism and chemical/biological defense; mechanisms of chemical inactivation of viruses; nanotechnology; exposure and risk assessment of single or multiple agents (mixtures); pathogenesis and mechanisms of neurodegenerative disease; organophosphorus compounds; serine hydrolases; mechanisms of oxidative stress and protein oxidation; plant analogs of mammalian proteins; heat and salt resistance in plants; insecticide resistance; boron chemistry and biology
Dr. David C. Lacy
E-Mail Website
Guest Editor
Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY 14260, USA
Interests: organomanganese; Mn(I) catalyzed; catalysis
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The Special Issue of the Molecular Structure section of Molecules commemorating the 25th anniversary of the journal will feature papers on element 25: manganese (Mn). Whereas manuscripts are sought that deal with the structural chemistry of Mn, we also invite contributions dealing with other aspects of Mn and/or other metals. Papers may include full-length research articles, short communications, or focused reviews. Subject matter may include, but not be limited by, the topics shown below in the keywords list.

Prof. Dr. Rudy J. Richardson
Dr. David C. Lacy
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • ­Compounds or complexes containing Mn and/or other metals.
  • Enzymes or other proteins containing Mn and/or other metals.
  • Redox chemistry of Mn and/or other metals and their compounds.
  • Electronic and magnetic properties of materials containing Mn and/or other metals.
  • Spectroscopy of Mn and/or other metals (e.g., NMR, MRI, EPR, NQR, UV/VIS, IR, 2D-IR).
  • Mass spectrometry of Mn and/or other metals.
  • Mn and/or other metals in health and disease.
  • Nutritional aspects of Mn and/or other metals.
  • Mineralogy, geochemistry, or biogeochemistry of Mn and/or other metals.
  • Nanomaterials containing Mn and/or other metals.
  • Organomanganese compounds

Published Papers (5 papers)

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Research

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Article
Mimicking Elementary Reactions of Manganese Lipoxygenase Using Mn-hydroxo and Mn-alkylperoxo Complexes
Molecules 2021, 26(23), 7151; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26237151 (registering DOI) - 25 Nov 2021
Viewed by 219
Abstract
Manganese lipoxygenase (MnLOX) is an enzyme that converts polyunsaturated fatty acids to alkyl hydroperoxides. In proposed mechanisms for this enzyme, the transfer of a hydrogen atom from a substrate C-H bond to an active-site MnIII-hydroxo center initiates substrate oxidation. In some [...] Read more.
Manganese lipoxygenase (MnLOX) is an enzyme that converts polyunsaturated fatty acids to alkyl hydroperoxides. In proposed mechanisms for this enzyme, the transfer of a hydrogen atom from a substrate C-H bond to an active-site MnIII-hydroxo center initiates substrate oxidation. In some proposed mechanisms, the active-site MnIII-hydroxo complex is regenerated by the reaction of a MnIII-alkylperoxo intermediate with water by a ligand substitution reaction. In a recent study, we described a pair of MnIII-hydroxo and MnIII-alkylperoxo complexes supported by the same amide-containing pentadentate ligand (6Medpaq). In this present work, we describe the reaction of the MnIII-hydroxo unit in C-H and O-H bond oxidation processes, thus mimicking one of the elementary reactions of the MnLOX enzyme. An analysis of kinetic data shows that the MnIII-hydroxo complex [MnIII(OH)(6Medpaq)]+ oxidizes TEMPOH (2,2′-6,6′-tetramethylpiperidine-1-ol) faster than the majority of previously reported MnIII-hydroxo complexes. Using a combination of cyclic voltammetry and electronic structure computations, we demonstrate that the weak MnIII-N(pyridine) bonds lead to a higher MnIII/II reduction potential, increasing the driving force for substrate oxidation reactions and accounting for the faster reaction rate. In addition, we demonstrate that the MnIII-alkylperoxo complex [MnIII(OOtBu)(6Medpaq)]+ reacts with water to obtain the corresponding MnIII-hydroxo species, thus mimicking the ligand substitution step proposed for MnLOX. Full article
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Article
Identification of Three Small Molecules That Can Selectively Influence Cellular Manganese Levels in a Mouse Striatal Cell Model
Molecules 2021, 26(4), 1175; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26041175 - 22 Feb 2021
Viewed by 661
Abstract
Manganese (Mn) is a biologically essential metal, critical as a cofactor for numerous enzymes such a glutamine synthetase and kinases such as ataxia-telangiectasia mutated (ATM). Similar to other essential metals such as iron and zinc, proper levels of Mn need to be achieved [...] Read more.
Manganese (Mn) is a biologically essential metal, critical as a cofactor for numerous enzymes such a glutamine synthetase and kinases such as ataxia-telangiectasia mutated (ATM). Similar to other essential metals such as iron and zinc, proper levels of Mn need to be achieved while simultaneously being careful to avoid excess levels of Mn that can be neurotoxic. A lifetime of occupational exposure to Mn can often lead to a Parkinsonian condition, also known as “manganism”, characterized by impaired gait, muscle spasms, and tremors. Despite the importance of its regulation, the mechanisms underlying the transport and homeostasis of Mn are poorly understood. Rather than taking a protein or gene-targeted approach, our lab recently took a high-throughput-screening approach to identify 41 small molecules that could significantly increase or decrease intracellular Mn in a neuronal cell model. Here, we report characterization of these small molecules, which we refer to as the “Mn toolbox”. We adapted a Fura-2-based assay for measuring Mn concentration and for measuring relative concentrations of other divalent metals: nickel, copper, cobalt, and zinc. Of these 41 small molecules, we report here the identification of three that selectively influence cellular Mn but do not influence the other divalent metals tested. The patterns of activity across divalent metals and the discovery of Mn-selective small molecules has potential pharmacological and scientific utility. Full article
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Article
Effects of Chemically-Modified Polypyridyl Ligands on the Structural and Redox Properties of Tricarbonylmanganese(I) Complexes
Molecules 2020, 25(24), 5921; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25245921 - 14 Dec 2020
Viewed by 631
Abstract
Carbonyl complexes with manganese(I) as the central metal are very attractive catalysts. The introduction of redox-active ligands, such as quinones and methyl viologen analogs into these catalysts, would be expected to lead to superior catalyst performances, since they can function as excellent electron [...] Read more.
Carbonyl complexes with manganese(I) as the central metal are very attractive catalysts. The introduction of redox-active ligands, such as quinones and methyl viologen analogs into these catalysts, would be expected to lead to superior catalyst performances, since they can function as excellent electron carriers. In this study, we synthesized four tricarbonylmanganese(I) complexes containing typical bidentate polypyridyl ligands, including 1,10-phenanthroline (phen) and 2,2′-bipyridine (bpy) frameworks bound to redox-active ortho-quinone/catechol or methyl viologen-like units. The molecular structures of the resulting complexes were determined by X-ray crystallography to clarify their steric features. As expected from the infrared (IR) data, three CO ligands for each complex were coordinated in the facial configuration around the central manganese(I) atom. Additionally, the structural parameters were found to differ significantly between the quinone/catechol units. Electrochemical analysis revealed some differences between them and their reference complexes, namely [MnBr(CO)3(phen)] and [MnBr(CO)3(bpy)]. Notably, interconversions induced by two-electron/two-proton transfers between the quinone and catechol units were observed in the phenanthroline-based complexes. This work indicated that the structural and redox properties in tricarbonylmanganese(I) complexes were significantly affected by chemically modified polypyridyl ligands. A better understanding of structures and redox behaviors of the present compounds would facilitate the design of new manganese complexes with enhanced properties. Full article
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Review

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Review
Textile Dye Biodecolorization by Manganese Peroxidase: A Review
Molecules 2021, 26(15), 4403; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26154403 - 21 Jul 2021
Viewed by 657
Abstract
Wastewater emissions from textile factories cause serious environmental problems. Manganese peroxidase (MnP) is an oxidoreductase with ligninolytic activity and is a promising biocatalyst for the biodegradation of hazardous environmental contaminants, and especially for dye wastewater decolorization. This article first summarizes the origin, crystal [...] Read more.
Wastewater emissions from textile factories cause serious environmental problems. Manganese peroxidase (MnP) is an oxidoreductase with ligninolytic activity and is a promising biocatalyst for the biodegradation of hazardous environmental contaminants, and especially for dye wastewater decolorization. This article first summarizes the origin, crystal structure, and catalytic cycle of MnP, and then reviews the recent literature on its application to dye wastewater decolorization. In addition, the application of new technologies such as enzyme immobilization and genetic engineering that could improve the stability, durability, adaptability, and operating costs of the enzyme are highlighted. Finally, we discuss and propose future strategies to improve the performance of MnP-assisted dye decolorization in industrial applications. Full article
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Review
Manganese Accumulation in the Brain via Various Transporters and Its Neurotoxicity Mechanisms
Molecules 2020, 25(24), 5880; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25245880 - 12 Dec 2020
Cited by 5 | Viewed by 1058
Abstract
Manganese (Mn) is an essential trace element, serving as a cofactor for several key enzymes, such as glutamine synthetase, arginase, pyruvate decarboxylase, and mitochondrial superoxide dismutase. However, its chronic overexposure can result in a neurological disorder referred to as manganism, presenting symptoms similar [...] Read more.
Manganese (Mn) is an essential trace element, serving as a cofactor for several key enzymes, such as glutamine synthetase, arginase, pyruvate decarboxylase, and mitochondrial superoxide dismutase. However, its chronic overexposure can result in a neurological disorder referred to as manganism, presenting symptoms similar to those inherent to Parkinson’s disease. The pathological symptoms of Mn-induced toxicity are well-known, but the underlying mechanisms of Mn transport to the brain and cellular toxicity leading to Mn’s neurotoxicity are not completely understood. Mn’s levels in the brain are regulated by multiple transporters responsible for its uptake and efflux, and thus, dysregulation of these transporters may result in Mn accumulation in the brain, causing neurotoxicity. Its distribution and subcellular localization in the brain and associated subcellular toxicity mechanisms have also been extensively studied. This review highlights the presently known Mn transporters and their roles in Mn-induced neurotoxicity, as well as subsequent molecular and cellular dysregulation upon its intracellular uptakes, such as oxidative stress, neuroinflammation, disruption of neurotransmission, α-synuclein aggregation, and amyloidogenesis. Full article
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