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4. Electrochemical and Mechanistic Characterization of Thiolate Ligand Modifications of [2fe-2s]-Based Electrocatalysts for Hydrogen Evolution

Author

Gianetti, Thomas, Miranda, Katrina M., Pemberton, Jeanne, Coen, Addison, Gianetti, Thomas, Miranda, Katrina M., Pemberton, Jeanne, and Coen, Addison

Abstract

Green hydrogen generation is currently a leading topic of research in the field of renewables and sustainable energy. The development of synthetic hydrogenase mimetics as catalysts for hydrogen evolution has emerged as a promising approach due to their relatively low cost and sustainability. Mimetics of the [2Fe-2S] active site, which are originally based on the active site of the [FeFe]-hydrogenase enzyme, have been shown to efficiently reduce protons to molecular hydrogen and help highlight interesting synthetic and spectroscopic insights into the improvement of catalytic capabilities of this class of complexes. These synthetic mimetics are typically defined by the composition and connectivity of the thiolato ligands to both each other and the [2Fe-2S] catalytic core. This dissertation focuses primarily on the effects that differences in the architecture of the thiolate attachments have on catalytic performance and mechanism for both molecular and metallopolymer type [2Fe-2S] catalysts.The complexes discussed in this dissertation underwent new electrochemical and spectroscopic experimentation that defined differences in their catalytic behavior. New spectroelectrochemical equipment and methodology were developed to make the first in situ spectroelectrochemical observations of the initially reduced and protonated catalytic intermediates for aryl dithiolate [2Fe-2S] catalysts in the presence of weak acids. These structural assignments were supported by improved DFT computations and led to the first refinement of the mechanistic paradigm for aryl dithiolate [2Fe-2S] catalysts in the presence of weak acids. Comparisons of new and existing aryl dithiolate [2Fe-2S] active sites in both the organic molecular and aqueous metallopolymer phases revealed the influence of metallopolymer system factors on active site catalytic behavior. These studies also highlighted limitations in the predictive power of [2Fe-2S] molecular system studies to predict catalytic properties of [2F

Published
2024

18. The Therapeutic Potential of Angeli’s Salt in Mitigating Acute Trypanosoma cruzi Infection in Mice

Author

Hideko Tatakihara, Vera Lúcia, primary, Malvezi, Aparecida Donizette, additional, Pereira, Rito Santo, additional, Lucchetti, Bruno Fernando Cruz, additional, Dos Santos, Lucas Felipe, additional, Cecchini, Rubens, additional, Yamauchi, Lucy Megumi, additional, Yamada-Ogatta, Sueli Fumie, additional, Miranda, Katrina M., additional, Verri, Waldiceu A., additional, Martins-Pinge, Marli Cardoso, additional, and Pinge-Filho, Phileno, additional

Published
2023
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21. Advancing Intracellular HNO Delivery Quantification and Integrated Strategies for Enhancing Sensitivity Through Monolith-Based Online Preconcentration Using Capillary Electrophoresis-Laser Induced Fluorescence Detection

Author

Pemberton, Jeanne E., Miranda, Katrina M., Gianetti, Thomas L., Amarakoon, Amarakoon Appuhamilage Thilini Navodi, Pemberton, Jeanne E., Miranda, Katrina M., Gianetti, Thomas L., and Amarakoon, Amarakoon Appuhamilage Thilini Navodi

Abstract

Capillary electrophoresis (CE) is a widely employed technique in life sciences, with applications in environmental, clinical, pharmaceutical, and food analysis. Among its various modes, capillary zone electrophoresis (CZE) stands out as the most commonly used due to its efficiency in achieving rapid separation. The flat flow profile within small-diameter capillaries further enhances separation efficiency, making it particularly effective for analyzing large biomarkers, as well as charged biomolecules such as proteins and signaling molecules. While UV detection is frequently utilized, techniques like laser-induced fluorescence (LIF) offer increased sensitivity. However, limitations arise from the ultra-small sample injection volume and the short optical path length, which can be mitigated by employing on-capillary preconcentration techniques, such as transient capillary isotachophoresis (tITP). Furthermore, CE-based flow-gated online injections prove indispensable for achieving high temporal resolution in monitoring time-sensitive reactions, enabling the study of dynamic processes and kinetics in a range of systems.The dissertation focuses on advancing the analysis of trace compounds by utilizing CZE, tITP-CZE, and flow-gated methods. It explores the quantitative analysis of intracellular nitroxyl (HNO) delivery, employing a fluorescent thiol-based trapping agent that eliminates the need for additional labeling steps. Through the use of CZE-LIF, HNO can be detected with good sensitivity, allowing for precise differentiation from other signals. It further introduces an analytical process that combines preconcentration through counterflow tITP within a monolith with CZE separation. Counterflow tITP-CZE addresses challenges such as flow dispersion and provides a stable porous medium for effective analyte preconcentration. Moreover, the addition of tITP-CZE in a flow-gated online injection system holds promise for the analysis of trace compounds and immunoassays, with fl

Published
2023

33. Nitric Oxide

Author

Thomas, Douglas D., Miranda, Katrina M., Citrin, Deborah, Espey, Michael G., Wink, David A., Tsokos, George C., editor, and Atkins, James L., editor

Published
2003
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42. Nitric Oxide Modulates Metabolic Processes in the Tumor Immune Microenvironment

Author

McGinity, Christopher L., primary, Palmieri, Erika M., additional, Somasundaram, Veena, additional, Bhattacharyya, Dibyangana D., additional, Ridnour, Lisa A., additional, Cheng, Robert Y. S., additional, Ryan, Aideen E., additional, Glynn, Sharon A., additional, Thomas, Douglas D., additional, Miranda, Katrina M., additional, Anderson, Stephen K., additional, Lockett, Stephen J., additional, McVicar, Daniel W., additional, and Wink, David A., additional

Published
2021
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44. Mechanism of aerobic decomposition of Angeli's salt (sodium trioxodinirate) at physiological pH

Author

Miranda, Katrina M., Dutton, Andrew S., Ridnour, Lisa A., Foreman, Christian A, Ford, Eleonara, Paolocci, Nazareno, Katori, Tatsuo, Mancardi Daniele, Tochetti, Carlo G., Thomas, Douglas D., Wink, David A., Fukuto, Jon M., Houk, K.N., and Espey, Micheal G.

Subjects
Quantum theory -- Research, Cardiovascular diseases -- Care and treatment, Nitrogen oxide -- Usage, Chemistry
Abstract

The determination that Angeli's salt may have clinical application as a nitrogen oxide donor for treatment of cardiovascular diseases such as heart failure has led to renewed interest in the mechanism and products of thermal decomposition of the salt under physiological conditions. Several mechanisms are evaluated experimentally and by quantum mechanical calculations to determine whether HNO is in fact released from Angeli's salt in neutral, aerobic solution.

Published
2005

46. Orthogonal properties of the redox siblings nitroxyl and nitric oxide in the cardiovascular system: a novel redox paradigm

Author

Wink, David A., Miranda, Katrina M., Katori, Tatsuo, Mancardi, Daniele, Thomas, Douglas D., Ridnour, Lisa, Espey, Michael G., Feelisch, Martin, Colton, Carol A., Futuko, Jon M., Pagliaro, Pasquale, Kass, David A., and Paolocci, Nazareno

Subjects
Nitric oxide -- Research, Peptides -- Research, Biological sciences
Abstract

Endogenous formation of nitric oxide (NO) and related nitrogen oxides in the vascular system is critical to regulation of multiple physiological functions. An imbalance in the production or availability of these species can result in progression of disease. Nitrogen oxide research in the cardiovascular system has primarily focused on the effects of NO and higher oxidation products. However, nitroxyl (HNO), the one-electron-reduction product of NO, has recently been shown to have unique and potentially beneficial pharmacological properties. HNO and NO often induce discrete biological responses, providing an interesting redox system. This article discusses the emerging aspects of HNO chemistry and attempts to provide a framework for the distinct effects of NO and HNO in vivo. guanosine 3',5'-cyclic monophosphate; calcitonin gene-related peptide; Angeli's salt

Published
2003

47. Positive inotropic and lusitropic effects of HNO/N[O.sup.-] in failing hearts: independence from [beta]-adrenergic signaling

Author

Paolocci, Nazareno, Katori, Tatsuo, Champion, Hunter C., St. John, Marcus E., Miranda, Katrina M., Fukuto, Jon M., Wink, David A., and Kass, David A.

Subjects
Heart failure -- Care and treatment, Science and technology
Abstract

Nitroxyl anion (HNO/N[O.sup.-]), the one-electron reduced form of nitric oxide (NO), induces positive cardiac inotropy and selective venodilation in the normal in vivo circulation. Here we tested whether HNO/N[O.sup.-] augments systolic and diastolic function of failing hearts, and whether contrary to NO/nitrates such modulation enhances rather than blunts [beta]-adrenergic stimulation and is accompanied by increased plasma calcitonin gene-related peptide (CGRP). HNO/N[O.sup.-] generated by Angelis' salt (AS) was infused (10 [micro]g/kg per min, i.v.) to conscious dogs with cardiac failure induced by chronic tachycardia pacing. AS nearly doubled contractility, enhanced relaxation, and lowered cardiac preload and afterload (all P < 0.001) without altering plasma cGMP. This contrasted to modest systolic depression induced by an NO donor diethylamine(DEA)/NO or nitroglycerin (NTG). Cardiotropic changes from AS were similar in failing hearts as in controls despite depressed [beta]-adrenergic and calcium signaling in the former. Inotropic effects of AS were additive to dobutamine, whereas DEA/NO blunted [beta]-stimulation and NTG was neutral. Administration of propranolol to nonfailing hearts fully blocked isoproterenol stimulation but had minimal effect on AS inotropy and enhanced lusitropy. Arterial plasma CGRP rose [beta]-fold with AS but was unaltered by DEA/NO or NTG, supporting a proposed role of this peptide to HNO/N[O.sup.-] cardiotropic action. Thus, HNO/N[O.sup.-] has positive inotropic and lusitropic action, which unlike NO/nitrates is independent and additive to [beta]-adrenergic stimulation and stimulates CGRP release. This suggests potential of HNO/N[O.sup.-] donors for the treatment of heart failure. nitroxyl | contractility | heart failure | nitric oxide | CGRP

Published
2003

50. Protein nitration is mediated by heme and free metals through Fenton-type chemistry: an alternative to the NO/[O.sup.-.sub.2] reaction

Author

Thomas, Douglas D., Espey, Michael Graham, Vitek, Michael P., Miranda, Katrina M., and Wink, David A.

Subjects
Nitration, Heme -- Physiological aspects, Science and technology
Abstract

The chemical origins of nitrated tyrosine residues (NT) formed in proteins during a variety of pathophysiological conditions remain controversial. Although numerous studies have concluded that NT is a signature for peroxynitrite (ONO[O.sup.-]) formation, other works suggest the primary involvement of peroxidases. Because metal homeostasis is often disrupted in conditions bearing NT, the role of metals as catalysts for protein nitration was examined. Cogeneration of nitric oxide (NO) and superoxide ([O.sup.-.sub.2]), from spermine/NO (2.7 [micro]M/min) and xanthine oxidase (1-28 [micro]M [O.sup.-.sub.2]/min), respectively, resulted in protein nitration only when these species were produced at approximately equivalent rates. Addition of ferriprotoporphyrin IX (hemin) to this system increased nitration over a broad range of 02 concentrations with respect to NO. Nitration in the presence of superoxide dismutase but not catalase suggested that ONO[O.sup.-] might not be obligatory to this process. Hemin-mediated NT formation required only the presence of N[O.sup.-.sub.2] and [H.sub.2][O.sub.2], which are stable end-products of NO and [O.sup.-.sub.2] degradation. Ferrous, ferric, and cupric ions were also effective catalysts, indicating that nitration is mediated by species capable of Fenton-type chemistry. Although ONO[O.sup.-] can nitrate proteins, there are severe spatial and temporal constraints on this reaction. In contrast, accumulation of metals and N[O.sup.-.sub.2] subsequent to NO synthase activity can result in far less discriminate nitration in the presence of an [H.sub.2][O.sub.2] source. Metal catalyzed nitration may account for the observed specificity of protein nitration seen under pathological conditions, suggesting a major role for translocated metals and the labilization of heme in NT formation. nitrotyrosine | nitric oxide | peroxynitrite | oxidation | hemin

Published
2002

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