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Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

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 …


Macromolecular Structure Determination At X-Ray Free Electron Lasers From Single-Particle Imaging To Time-Resolved X-Ray Crystallography, Ishwor Poudyal Dec 2020

Macromolecular Structure Determination At X-Ray Free Electron Lasers From Single-Particle Imaging To Time-Resolved X-Ray Crystallography, Ishwor Poudyal

Theses and Dissertations

X-ray free-electron lasers (XFELs) open the possibility of obtaining diffraction information from a single biological macromolecule. This is because XFELs can generate extremely intense X-ray pulses which are so short that diffraction data can be collected before the sample is destroyed. By collecting a sufficient number of single-particle diffraction patterns from many tilts of a molecule relative to the X-ray beam, the three-dimensional electron density can be reconstructed ab-initio. The resolution and therefore the information content of the data will ultimately depend largely on the number of patterns collected at the experiment. We estimate the number of diffraction patterns required …


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 …