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You searched for subject:(nitric oxide reductases). Showing records 1 – 2 of 2 total matches.

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1. Mahinthichaichan, Paween. Microscopic description of gas permeation and delivery pathways in biological macromolecules.

Degree: PhD, Biochemistry, 2016, University of Illinois – Urbana-Champaign

Life on Earth fundamentally and indispensably relies on proper regulation and metabolism of inorganic molecules such as dioxygen (O2), nitric oxide (NO), carbon dioxide (CO2) and ammonia (NH3). These chemical species often act as substrates of enzymes and/or as ligands modulating biochemical cascades, so elucidating their delivery and transport is imminent towards understanding cellular functions. Destinated targets (i.e. proteins and enzymes) of these molecules are often separated from exterior environments by layers or shells coated not only membrane lipids but also, in some cases, proteins, effectively forming physical barriers against their passage. For instance, catalytic site of many enzymes are sequestered deeply inside, while there is no clearly defined pathways for substrate delivery and product removal. Since gaseous molecules such as O2, NO, CO2 and NH3 have tiny volumes, probing their interactions with their surroundings within a medium requires techniques that provide both atomic spatial and small temporal resolutions. To fulfill these purposes, I have employed molecular dynamics (MD) simulation to characterize delivery pathways of O2, NO and CO2 in aerobic respiratory terminal oxidases (cytochrome ba3 and cytochrome aa3), nitric oxide reductase (cNOR) and bacterial carboxysome, and to describe the movement of O2, CO2 and NH3 through lipid membranes and membrane channels. In the first part of this dissertation, I illustrated the necessity of pathways in assuring optimal delivery of O2 or NO to the terminal oxidases and cNOR, which are homologous enzymes, under physiological conditions. The conclusions from the studies are correlated to the experimental measurements. Although O2 and NO are readily dissolved in membrane lipids, they migrate to the reduction site exclusively via a pre-formed hydrophobic tunnel. The unobstructed pathway in cytochrome ba3 ultimately permits the substrate(s) to migrate at the maximum diffusion rate (109 M^−1 s^−1), which is faster than through partially constricted pathways in cytochrome aa3 and cNOR. I then characterized the permeation of CO2 fixation substrates through the carboxysome shell of cyanobacteria, which is an assembled layer of shell proteins. The results of energetic analysis characterized a pore within each shell protein to be permeable to bicarbonate (HCO3- ) rather than CO2 and O2. The preferred uptake of HCO3- is advantageous of enhancing the incorporation of CO2 into biomass and mitigating the wasteful O2 fixation. The enzyme carbonic anhydrase inside the carboxysomal lumen can readily convert HCO3- to CO2. In the second part of this dissertation, I examined the permeability of O2 and CO2 across lipid membranes varied by ratios of glycerolphospholipids, cholesterol and sphinogomyelins, which are major constituents of mammalian membranes. This study shows that membrane lipid compositions modulate the permeability of nonpolar gases, emphasizing the existence of gas-impermeable membranes and significance of membrane-facilitated gas channels. I have also… Advisors/Committee Members: Tajkhorshid, Emad (advisor), Tajkhorshid, Emad (Committee Chair), Gennis, Robert B (Committee Chair), Crofts, Antony R (committee member), Grosman, Claudio F (committee member).

Subjects/Keywords: Molecular dynamic simulation; Enhanced sampling techniques; Free energy calculations; Gas permeation and transport; Dioxygen; Nitric oxide; Carbon dioxide; Ammonia; Bicarbonate and ions; Proteins; Enzymes; Ligands; Substrates; Hydrophobic tunnels; Bioenergetics; Aerobic respiration; Terminal oxidases; Bacterial denitrification; nitric oxide reductases; Carbon dioxide fixation; Bacterial carboxysome; Membrane permeability; Glycerophospholipids; Cholesterol; Sphingomyelin; Aquaporins; Aquaglyceroporins

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Mahinthichaichan, P. (2016). Microscopic description of gas permeation and delivery pathways in biological macromolecules. (Doctoral Dissertation). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/95310

Chicago Manual of Style (16th Edition):

Mahinthichaichan, Paween. “Microscopic description of gas permeation and delivery pathways in biological macromolecules.” 2016. Doctoral Dissertation, University of Illinois – Urbana-Champaign. Accessed October 14, 2019. http://hdl.handle.net/2142/95310.

MLA Handbook (7th Edition):

Mahinthichaichan, Paween. “Microscopic description of gas permeation and delivery pathways in biological macromolecules.” 2016. Web. 14 Oct 2019.

Vancouver:

Mahinthichaichan P. Microscopic description of gas permeation and delivery pathways in biological macromolecules. [Internet] [Doctoral dissertation]. University of Illinois – Urbana-Champaign; 2016. [cited 2019 Oct 14]. Available from: http://hdl.handle.net/2142/95310.

Council of Science Editors:

Mahinthichaichan P. Microscopic description of gas permeation and delivery pathways in biological macromolecules. [Doctoral Dissertation]. University of Illinois – Urbana-Champaign; 2016. Available from: http://hdl.handle.net/2142/95310


Loma Linda University

2. Jones, Jesica Ann. Dietary Intake and Bio-activation of Nitrite and Nitrate in Newborn Infants.

Degree: PhD, Basic Sciences, 2015, Loma Linda University

Nitrate and nitrite are commonly thought of as inert end products of nitric oxide (NO) oxidation, possibly carcinogenic food additives, or well-water contaminants. However, recent studies have shown that nitrate and nitrite play an important role in cardiovascular and gastrointestinal homeostasis through conversion back into NO via a physiological system involving enterosalivary recirculation, bacterial nitrate reductases, and enzyme-catalyzed or acidic reduction of nitrite to NO. The diet is a key source of nitrate in adults; however, infants ingest significantly less nitrate due to low concentrations in breast milk. In the mouth, bacteria convert nitrate to nitrite, which has gastro-protective effects. However, these nitrate-reducing bacteria are relatively inactive in infants. Swallowed nitrite is reduced to NO by acid in the stomach, affecting gastric blood flow, mucus production, and the gastric microbiota. These effects are likely attenuated in the less acidic neonatal stomach. Systemically, nitrite acts as a reservoir of NO bioactivity that can protect against ischemic injury, yet plasma nitrite concentrations fall dramatically at birth and remain markedly lower than in adults for the first few weeks of life. The physiological importance of the diminished nitrate→nitrite→NO axis in infants and its implications in the etiology and treatment of newborn diseases such as necrotizing enterocolitis and hypoxic/ischemic injury are yet to be determined. Advisors/Committee Members: Blood, Arlin B., Hopper, Andrew, Patel, Rakesh, Power, Gordon, Zhang, Lubo.

Subjects/Keywords: Chemical and Pharmacologic Phenomena; Medical Pharmacology; Medicine and Health Sciences; Infant - Newborn; Infant Nutritional Physiological Phenomena; Homeostasis; Diet; Milk - Human; Infant Formula; Nitrates - Metabolism; Nitrites - Metabolism; Saliva - Metabolism; Gastrointestional Tract; Nitric Oxide Oxidation; Cardiovascular Homeostasis; Gastrointestinal Homeostasis; Enterosalivary recirculation; Bacterial Nitrate Reductases; Gastro-protective Effects

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Jones, J. A. (2015). Dietary Intake and Bio-activation of Nitrite and Nitrate in Newborn Infants. (Doctoral Dissertation). Loma Linda University. Retrieved from https://scholarsrepository.llu.edu/etd/274

Chicago Manual of Style (16th Edition):

Jones, Jesica Ann. “Dietary Intake and Bio-activation of Nitrite and Nitrate in Newborn Infants.” 2015. Doctoral Dissertation, Loma Linda University. Accessed October 14, 2019. https://scholarsrepository.llu.edu/etd/274.

MLA Handbook (7th Edition):

Jones, Jesica Ann. “Dietary Intake and Bio-activation of Nitrite and Nitrate in Newborn Infants.” 2015. Web. 14 Oct 2019.

Vancouver:

Jones JA. Dietary Intake and Bio-activation of Nitrite and Nitrate in Newborn Infants. [Internet] [Doctoral dissertation]. Loma Linda University; 2015. [cited 2019 Oct 14]. Available from: https://scholarsrepository.llu.edu/etd/274.

Council of Science Editors:

Jones JA. Dietary Intake and Bio-activation of Nitrite and Nitrate in Newborn Infants. [Doctoral Dissertation]. Loma Linda University; 2015. Available from: https://scholarsrepository.llu.edu/etd/274

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