Browsing by Author "Pluth, Michael D."

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    Bis(aryl) Tetrasulfides as Cathode Materials for Rechargeable Lithium Batteries
    (Wiley, 2017) Guo, Wei; Wawrzyniakowski, Zachary D.; Cerda, Matthew M.; Bhargav, Amruth; Pluth, Michael D.; Ma, Ying; Fu, Yongzhu; Department of Mechanical Engineering, School of Engineering and Technology
    An organotetrasulfide consists of a linear chain of four sulfur atoms that could accept up to 6 e− in reduction reactions, thus providing a promising high-capacity electrode material. Herein, we study three bis(aryl) tetrasulfides as cathode materials in lithium batteries. Each tetrasulfide exhibits two major voltage regions in the discharge. The high voltage slope region is governed by the formation of persulfides and thiolates, and the low voltage plateau region is due to the formation of Li2S2/Li2S. Based on theoretical calculations and spectroscopic analysis, three reduction reaction processes are revealed, and the discharge products are identified. Lithium half cells with tetrasulfide catholytes deliver high specific capacities over 200 cycles. The effects of the functional groups on the electrochemical characteristics of tetrasulfides are investigated, which provides guidance for developing optimum aryl polysulfides as cathode materials for high energy lithium batteries.
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    Comment on “Evidence that the ProPerDP method is inadequate for protein persulfidation detection due to lack of specificity”
    (American Association for the Advancement of Science, 2021-04-21) Dóka, Éva; Arnér, Elias S.J.; Schmidt, Edward E.; Dick, Tobias P.; van der Vliet, Albert; Yang, Jing; Szatmári, Réka; Ditrói, Tamás; Wallace, John L.; Cirino, Giuseppe; Olson, Kenneth; Motohashi, Hozumi; Fukuto, Jon M.; Pluth, Michael D.; Feelisch, Martin; Akaike, Takaaki; Wink, David A.; Ignarro, Louis J.; Nagy, Péter; Medicine, School of Medicine
    The recent report by Fan et al. alleged that the ProPerDP method is inadequate for the detection of protein persulfidation. Upon careful evaluation of their work, we conclude that the claim made by Fan et al. is not supported by their data, rather founded in methodological shortcomings. It is understood that the ProPerDP method generates a mixture of cysteine-containing and non–cysteine-containing peptides. Instead, Fan et al. suggested that the detection of non–cysteine-containing peptides indicates nonspecific alkylation at noncysteine residues. However, if true, then such peptides would not be released by reduction and therefore not appear as products in the reported workflow. Moreover, the authors’ biological assessment of ProPerDP using Escherichia coli mutants was based on assumptions that have not been confirmed by other methods. We conclude that Fan et al. did not rigorously assess the method and that ProPerDP remains a reliable approach for analyses of protein per/polysulfidation.
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    Effects of Manganese Porphyrins on Cellular Sulfur Metabolism
    (MDPI, 2020-02) Olson, Kenneth R.; Gao, Yan; Steiger, Andrea K.; Pluth, Michael D.; Tessier, Charles R.; Markel, Troy A.; Boone, David; Stahelin, Robert V.; Batinic-Haberle, Ines; Straubg, Karl D.; Pediatrics, School of Medicine
    Manganese porphyrins (MnPs), MnTE-2-PyP5+, MnTnHex-2-PyP5+ and MnTnBuOE-2-PyP5+, are superoxide dismutase (SOD) mimetics and form a redox cycle between O2 and reductants, including ascorbic acid, ultimately producing hydrogen peroxide (H2O2). We previously found that MnPs oxidize hydrogen sulfide (H2S) to polysulfides (PS; H2Sn, n = 2–6) in buffer. Here, we examine the effects of MnPs for 24 h on H2S metabolism and PS production in HEK293, A549, HT29 and bone marrow derived stem cells (BMDSC) using H2S (AzMC, MeRho-AZ) and PS (SSP4) fluorophores. All MnPs decreased intracellular H2S production and increased intracellular PS. H2S metabolism and PS production were unaffected by cellular O2 (5% versus 21% O2), H2O2 or ascorbic acid. We observed with confocal microscopy that mitochondria are a major site of H2S production in HEK293 cells and that MnPs decrease mitochondrial H2S production and increase PS in what appeared to be nucleoli and cytosolic fibrillary elements. This supports a role for MnPs in the metabolism of H2S to PS, the latter serving as both short- and long-term antioxidants, and suggests that some of the biological effects of MnPs may be attributable to sulfur metabolism.