Physical Sciences and Mathematics Commons^™

3-Hydroxyflavones And 3-Hydroxy-4-Oxoquinolines As Carbon Monoxide-Releasing Molecules, Tatiana Soboleva, Lisa M. Berreau

Chemistry and Biochemistry Faculty Publications

Carbon monoxide-releasing molecules (CORMs) that enable the delivery of controlled amounts of CO are of strong current interest for applications in biological systems. In this review, we examine the various conditions under which CO is released from 3-hydroxyflavones and 3-hydroxy-4-oxoquinolines to advance the understanding of how these molecules, or derivatives thereof, may be developed as CORMs. Enzymatic pathways from quercetin dioxygenases and 3-hydroxy-4-oxoquinoline dioxygenases leading to CO release are examined, along with model systems for these enzymes. Base-catalyzed and non-redox-metal promoted CO release, as well as UV and visible light-driven CO release from 3-hydroxyflavones and 3-hydroxy-4-oxoquinolines, are summarized. The visible …

Catalytic Mechanism For The Conversion Of Salicylate Into Catechol By The Flavin-Dependent Monooxygenase Salicylate Hydroxylase, Débora M. A. Costa, Stefanya V. Gómez, Simara S. De Araújo, Mozart S. Pereira, Rosemeire B. Alves, Denize C. Favaro, Alvan C. Hengge, Ronaldo A. P. Nagem, Tiago A. S. Brandão

Chemistry and Biochemistry Faculty Publications

Salicylate hydroxylase (NahG) is a flavin-dependent monooxygenase that catalyzes the decarboxylative hydroxylation of salicylate into catechol in the naphthalene degradation pathway in Pseudomonas putida G7. We explored the mechanism of action of this enzyme in detail using a combination of structural and biophysical methods. NahG shares many structural and mechanistic features with other versatile flavin-dependent monooxygenases, with potential biocatalytic applications. The crystal structure at 2.0 Å resolution for the apo form of NahG adds a new snapshot preceding the FAD binding in flavin-dependent monooxygenases. The k_cat/K_m for the salicylate reaction catalyzed by the holo form is …

Substrate Binding And Reduction Mechanism Of Molybdenum Nitrogenase, Zhiyong Yang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

As a key constituent of proteins, nucleic acids, and other biomolecules, nitrogen is essential to all living organisms including human beings. Dinitrogen represents the largest pool of nitrogen, about 79% of the Earth’s atmosphere, yet it is unusable by most living organisms due to its inertness. There are two ways to fix this inert dinitrogen to usable ammonia. One is the industrial Haber-Bosch process, which needs to be conducted at high temperature and pressure. This process uses a lot of the non-renewable fossil fuel as the energy source. The other major pathway is the biological nitrogen fixation carried out by …

The Magnitude And Mechanism Of Charge Enhancement Of Ch∙∙O H-Bonds, U. Adhikari, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Quantum calculations find that neutral methylamines and thioethers form complexes, with N-methylacetamide (NMA) as proton acceptor, with binding energies of 2–5 kcal/mol. This interaction is magnified by a factor of 4–9, bringing the binding energy up to as much as 20 kcal/mol, when a CH3+ group is added to the proton donor. Complexes prefer trifurcated arrangements, wherein three separate methyl groups donate a proton to the O acceptor. Binding energies lessen when the systems are immersed in solvents of increasing polarity, but the ionic complexes retain their favored status even in water. The binding energy is reduced when the methyl …

Structural And Mechanistic Investigations Of Phosphothreonine Lyase Class Of Enzymes, Alok Gopalkrishna Shenoy

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Phosphorylation and dephosphorylation are a highly pervasive mechanism in biology that is used by the cell to modulate enzymes and proteins. The presence of a phosphate group can activate or deactivate an enzyme. The phosphate group is linked to a protein by a phosphoester bond that is known to be highly stable in cytoplasmic pH range. Thus the breaking and formation of these bonds need to be effected by enzymes.

Recent discovery of the activity carried out by certain virulence related proteins (OspF released by Shigella and SpvC released by Salmonella) have resulted in a necessity to create a new …

Role Of Iron In The Mechanism Of Asbestos-Induced Apoptosis In Human Lung And Pleural Target Cells, Aleksander Baldys

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Occupational exposure to asbestos has been associated with increased incidence of pulmonary interstitial fibrosis, mesothelioma of the pleura, and bronchogenic carcinoma. Although the mechanism by which asbestos causes cancer remains unknown, iron associated with asbestos is thought to play a role in the pathogenic effects of fibers.

The aim of this research was to examine and compare the asbestos-induced signaling phenomena in relevant human lung and pleural target cells, and to determine the role of iron from asbestos fibers in these events. Exposure of human airway epithelial (A549) cells, human pleural mesothelial (MET5A) cells, and normal human small airway epithelial …

Mechanism Of Two Homogeneous Reactions; Co Self Exchange And N2 Self Exchange, Alan L. Rockwood

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The two atom switching reactions referred to in the title were originally studied at temperatures greater than 2000°K in shock tubes by other investigators. For each reaction they proposed a direct four-center exchange mechanism in which one of the reactant molecules must be vibrationally excited, (the vibrational excitation mechanism or VEM). One of the predictions of the VEM is that molecules which are vibrationally hot but translationally cold should react through the four center transition state that leads to exchange.

Using a mercury photosensitization technique, it is shown in the present work that excitation of CO to high vibrational levels …

The Kinetics And Mechanism Of The Reaction Of Molybdenum(V) With Iodine, Oxygen And Nitrate, Ervin Park Guymon

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Molybdenum compounds present a series of baffling chemical puzzles. By no means are all of these yet even clearly defined and many may never be. This complexity results from the ability of molybdenum to form six different oxidation states, which can possess three different coordination numbers. Furthermore, molybdenum compounds readily disproportionate to yield mixed valence compounds; and finally, molybdate ions readily aggregate in solution to form a variety of polyions by polymerization-condensation reactions which are controlled by pH and the concentration of the system. Molybdenum's complexity can best be summed up in the words of the late Edgar Smith who …