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Method Development And Applications To Screening And Characterization Of Rrna-Targeting Small Molecules, Papa Nii Asare-Okai

Wayne State University Dissertations

A series of single ring aminoglycoside analogues was tested for binding to a model RNA representing the A site using electrospray ionization mass spectrometry (ESI-MS). Several of the synthetic analogues with low molecular weights were found to bind to the RNA with affinities comparable to the parental aminoglycoside neamine, with apparent dissociation constants in the low micromolar range. Salt dependence of the affinity constants for the single ring analogues revealed a predominantly electrostatic binding mode. Footprinting experiments revealed that one of the compounds (DHR23) has a similar binding site as the antibiotic paromomycin. DMS chemical probing results also suggest that …

Nmr Solution Structures Of Two Hairpins Of E. Coli 16s Rrna: The Effects Of Mutations And Chemical Modifications On Structure And Function Of Rrna, Yu Liu

Wayne State University Dissertations

The structures of two functional mutants, the UC (G690U, U697C) and the QM mutants (G690A, G693C, A695C, U697A) of the 690 hairpin of E. coli 16S ribosomal RNA were determined by NMR. The UC mutant and the QM mutant with high biological function are able to fold into structures that are isomorphous with the wild-type 690 hairpin sequence. The structural comparisons among the functional mutants and the wild-type provides structural validation for previously identified specific functional groups that are crucial for maintaining function of the 690 hairpin. The key groups for maintaining the structure and function of the 690 loop …

Crystallographic, Molecular Dynamics, And Enzymatic Studies Of Multi-Drug Resistant Hiv-1 Protease And Implications For Structure Based Drug Design (Project 1); Crystallographic Studies Of Human Myelin Protein Zero (Project 2), Zhigang Liu

Wayne State University Dissertations

Under drug selection pressure, emerging mutations render HIV-1 protease drug resistance, leading to the therapy failure in anti-HIV treatment.Tthe multidrug-resistant 769 (MDR) HIV-1 protease (resistant mutations at residues 10, 36, 46, 54, 62, 63, 71, 82, 84, 90) is selected for the present study to understand drug resistance issue.

Ten additional mutations are introduced to MDR769 HIV-1 protease to study the structural influences brought by these mutations. We get crystal structures of four variants (I10V, A82F, A82S and A82T) of MDR769 HIV-1 protease. All these mutations fail to further open the flaps and expand the active site cavity of MDR769 …

Enzymology And Medicinal Chemistry Of N5-Carboxyaminoimidazole Ribonucleotide Synthetase : A Novel Antibacterial Target, Hanumantharao Paritala

Wayne State University Dissertations

N5-Carboxyaminoimidazole ribonucleotide synthetase (N5-CAIR synthetase), a key enzyme in microbial de novo purine biosynthesis, catalyzes the conversion of aminoimidazole ribonucleotide (AIR) to N5-CAIR. To date, this enzyme has been observed only in microorganisms, and thus, it represents an ideal target for antimicrobial drug development. Here we report structural and functional studies on the Aspergillus clavatus N5-CAIR synthetase and identification of inhibitors for the enzyme. In collaboration with Dr. Hazel Holden of the University of Wisconsin, the three-dimensional structure of Aspergillus clavatus N5-CAIR synthetase was solved in the presence of either Mg2ATP or MgADP and AIR. These structures, determined to 2.1 …

Characterization Of Arsd: An Arsenic Chaperone For The Arsab As(Iii)-Translocating Atpase, Jianbo Yang

Wayne State University Dissertations

Arsenic is a metalloid toxicant that is widely distributed throughout the earth's crust and causes a variety of health and environment problems. As an adaptation to arsenic-contaminated environments, organisms have developed resistance systems. In bacteria and archaea various ars operons encode ArsAB ATPases that pump the trivalent metalloids As(III) or Sb(III) out of cells. In these operons, an arsD gene is almost always adjacent to the arsA gene, suggesting a related function. ArsA is the catalytic subunit of the pump that hydrolyzes ATP in the presence of arsenite or antimonite. ArsB is a membrane protein which containing arsenite-conducting pathway. ArsA …

Isothermal Titration Calorimetry Studies Of Protein-Mediated Interactions And Preliminary Structural Studies Of Tandem Pdz1-2 Domain Of Psd-95 Protein, Ana Jankovic

Wayne State University Dissertations

Protein-mediated interactions that involve multiple ligands in their binding mechanisms are critical for many cellular functions. The primary focus of this dissertation research was to investigate such interactions for two proteins, the PDZ domain and frataxin, involving peptide and metal binding ligands, respectively. The three component projects of this work comprised (1) thermodynamic analysis of PDZ domain binding using calorimetry; (2) X-ray crystallographic structural studies of a PDZ dual domain; and (3) thermodynamic analysis of frataxin binding to iron. The specific goal of the research conducted with the PDZ domains was to understand the mechanism of action of multiple/tandem protein …