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Full-Text Articles in Life Sciences

A Mechanistic Investigation Of Cytochrome C Nitrite Reductase Catalyzed Reduction Of Nitrite To Ammonia: The Search For Catalytic Intermediates, Shahid Shahid Dec 2020

A Mechanistic Investigation Of Cytochrome C Nitrite Reductase Catalyzed Reduction Of Nitrite To Ammonia: The Search For Catalytic Intermediates, Shahid Shahid

Theses and Dissertations

Cytochrome c Nitrite Reductase (ccNiR) is a periplasmic homodimeric decaheme enzyme that catalyzes the reduction of nitrite to ammonium in a process that involves six electrons and eight protons. Under standard assay conditions, which use a strong reducing agent as an electron source, catalysis takes place rapidly without producing detectable intermediates. However, intermediates do accumulate when weaker reducing agents are employed, allowing the ccNiR mechanism to be studied. Herein, the early stages of Shewanella oneidensis ccNiR-catalyzed nitrite reduction were investigated in isolation by using the weak reducing agents N,N,N’,N’-tetramethyl-p-phenylenediamine (TMPD) and the 2-electron reduced form of indigo trisulfonate. Experiments were …


Structural And Functional Characterization Of L-Enduracididine Biosynthetic Enzymes, Nemanja Vuksanovic Dec 2020

Structural And Functional Characterization Of L-Enduracididine Biosynthetic Enzymes, Nemanja Vuksanovic

Theses and Dissertations

The mannopeptimycins produced by Streptomyces hygroscopicus are non-ribosomal peptide antibiotics with activity against a number of Gram-positive pathogens, including drug-resistant strains like methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Attempts to synthesize more potent mannopeptimycin analogues have so far not been successful. One reason this has proven difficult is that the mannopeptimycins contain the unusual non-proteinogenic amino acid L-enduracididine (L-End), or its hydroxylated derivative β-hydroxy enduracididine (βhEnd,). This amino acid is not commercially available and, while synthetic routes have been developed, they are multi-step processes starting from an advanced intermediate. Understanding enzymatic synthesis of L-End is an important goal, …


Quagga Mussel Induced Phosphorus Cycling Changes In Lake Michigan, Rae-Ann Maclellan-Hurd Aug 2020

Quagga Mussel Induced Phosphorus Cycling Changes In Lake Michigan, Rae-Ann Maclellan-Hurd

Theses and Dissertations

Quagga mussels (Dreissena rostriformis bugensis) are an invasive ecosystem engineer that have successfully colonized both profundal and nearshore regions in Southern Lake Michigan. Quagga mussels directly altered the flow of nutrients by filtering particles, excretion of soluble forms of nutrients in the benthos, and through the production of biodeposits. Mussel excretion, egestion, and capture rates of P were compared between a 25 meter and a 55 meter deep site near Milwaukee Harbor to determine the retention of nutrients in these regions. The capture rate of particulate phosphorus at the 25m site (278 ± 388 μmol m-2) was similar to that …


Understanding The Role Of Protein Kinases Kin1 And Kin2 In The Protein Folding Pathways In The Yeast Saccharomyces Cerevisiae, Chandrima Ghosh May 2020

Understanding The Role Of Protein Kinases Kin1 And Kin2 In The Protein Folding Pathways In The Yeast Saccharomyces Cerevisiae, Chandrima Ghosh

Theses and Dissertations

Eukaryotic protein kinases catalyze the transfer of the -phosphate of an ATP to a serine/threonine/tyrosine residue present in a protein substrate. The phosphorylation of proteins has profound effects on their activity and protein-protein interactions, thus regulating a plethora of cellular processes, including cell growth, differentiation and protein homeostasis (or proteostasis). Our lab is the first to demonstrate that protein kinases Kin1 and its paralog Kin2 in the budding yeast Saccharomyces cerevisiae, orthologs of human microtubule affinity-regulating kinase (MARK), contribute to protein-folding homeostasis inside the endoplasmic reticulum (ER), in addition to their canonical roles in cellular exocytosis. The main aim of …


Zinc Proteomics: Interactions Of Zn2+, Cd2+, And Metal-Binding Ligands With Zn-Binding Sites In The Proteome, Eric Daniel Lund May 2020

Zinc Proteomics: Interactions Of Zn2+, Cd2+, And Metal-Binding Ligands With Zn-Binding Sites In The Proteome, Eric Daniel Lund

Theses and Dissertations

Cadmium ion causes toxicity in humans, most prominently in the kidney. This thesis focuses on mechanisms by which Cd2+ harms kidney proximal tubule cells. Previous experiments have shown the time-dependent distribution of Cd2+ and Zn2+ within supernatant of pig kidney, LLC-PK1 cells after exposure to Cd2+ plus the ionophore pyrithione1. The first part of this research describes the trafficking of cadmium within LLC-PK1 proximal tubule cells, including the time dependent distribution, speciation, and quantification of Cd2+ and Zn2+ in cells exposed to Cd2+ and Cd2+ plus pyrithione. The latter treatment introduces Cd2+ into cells at time zero and permits the …