Theses and Dissertations at Montana State University (MSU)
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Item The preparation, characterization, and chemistry of trisubstituted platinacyclobutanes and platinacyclopentanes(Montana State University - Bozeman, College of Letters & Science, 1989) Neilsen, William DwightItem A study of the crystal structure of pervanadyl trimethoxide(Montana State University - Bozeman, College of Letters & Science, 1957) Ryder, Walter A.Item The X-ray crystallographic determination of the structures of the CIS para-menthane thiourea adduct and 1,2,4 trichlorobenzene-1,2,4 trimethylbenzene thiourea adduct(Montana State University - Bozeman, College of Engineering, 1986) Spinti, Mark JohnItem The X-ray crystallographic structure study of the 1,2,4 trimethybenzene thiourea adduct and 1,2,4 trichlorobenzene thiourea adduct(Montana State University - Bozeman, College of Engineering, 1986) Wick, Thomas AlbertItem X-ray crystallographic studies of sulfolobus turetted icosahedral virus (STIV) : a hyperthermophilic virus from Yellowstone National Park(Montana State University - Bozeman, College of Letters & Science, 2006) Larson, Eric Thomas; Chairperson, Graduate Committee: C. Martin LawrenceSulfolobus turreted icosahedral virus (STIV) was isolated from acidic hot springs of Yellowstone National Park and was the first hyperthermophilic virus described with icosahedral capsid architecture. Structural analysis of the STIV particle and its major capsid protein suggests that it belongs to a lineage of viruses that predates the division of the three domains of life. Functional predictions of the viral proteins are hindered because they lack similarity to sequences of known function. Protein structure, however, may suggest functional relationships that are not apparent from the sequence. Thus, we have initiated crystallographic studies of STIV and expect to gain functional insight into its proteins while illuminating the viral life cycle. These studies may also provide genetic, biochemical, and evolutionary insight into its thermoacidophilic host and the requirements for life in these harsh environments. The first three proteins studied in structural detail are A197, B116, and F93. As anticipated, these structures suggest possible functions. The structure of A197 reveals a glycosyltransferase GT-A fold.Item Structural studies of enzymes involved in propylene and acetone metabolism in Xanthobacter autotrophicus(Montana State University - Bozeman, College of Letters & Science, 2007) Krishnakumar, Arathi Mandyam; Chairperson, Graduate Committee: John W. PetersX-ray crystallography has been an indispensable tool in understanding the mechanism of the enzymes of the epoxide carboxylation pathway in Xanthobacter autotrophicus. The main focus of this dissertation involves providing the structural basis for the stereoslectivity of the two stereospecific dehydrogenases of the pathway namely R- and S-HPCDH. The crystal structure of R- HPCDH cocrystallized with the substrate has been determined. The key elements of interactions between the enzyme and substrate are electrostatic interactions between the sulfonate oxygen atoms and two arginine residues (Arg152 and Arg196) of R- HPCDH. The comparison of the structure of R- HPCDH with a homology model of the S-HPCDH provides a structural basis for a mechanism of substrate specificity in which the binding of the substrate sulfonate moiety at distinct sites on each stereoselective enzyme directs the orientation of the appropriate substrate enantiomer for hydride abstraction. Moreover, crystal structures of the two methionine mutants of R-HPCDH have revealed that they have a role in shielding electrostatic interactions between the enzyme and the substrate from the surroundings. The structure of the presumed product bound state reveals that binding interactions between the substrate and the enzyme have striking similarities to the ones observed in the previously determined structure of 2-KPCC highlighting the utility of coenzyme M as a carrier molecule in the pathway. Extensive comparative structural analyses of the enzymes of the pathway reveal a common structural signature for coenzyme M binding. Coenzyme M, when conjugated with the substrates that lack innate chemical groups, such as short chain alkenes and epoxides, provide these substrates a handle to specifically bind and interact with the enzymes, thereby orienting them in a proper fashion for catalysis. Finally, exhaustive amount of ground work is laid towards the determination of the three dimensional structure of acetone carboxylase, the enzyme which converts acetone to acetoacetate in Xanthobacter. Initial electron density maps calculated by the phase information obtained from a number of moderately good heavy atom derivatives show a clear protein-solvent envelope, providing the first glimpse into the three dimensional structure of acetone carboxylase.Item X-ray crystallographic studies of the proteins from sulfolobus spindle-shaped viruses (SSVs)(Montana State University - Bozeman, College of Letters & Science, 2009) Menon, Smita Kesavankutty; Chairperson, Graduate Committee: C. Martin LawrenceViruses populate virtually every ecosystem on the planet. Fuselloviridae are ubiquitous crenarchaeal viruses found in high-temperature acidic hot springs around the world. However, compared to eukaryotic and bacterial viruses, our knowledge of viruses infecting the archaea is limited. Fuselloviral genomes show little similarity to other organisms, generally precluding functional predictions. However, structural studies can reveal distant evolutionary relationships and provide functional insights that are not apparent from the primary amino acid sequence alone. Several such structural studies have already contributed to our understanding of the Sulfolobus Spindle-shaped viruses (Fuselloviridae). Here we report the structure of two proteins, SSV1 F112 and SSVRH D212. Biochemical, proteomic and structural studies of F112 reveal a monomeric intracellular protein that adopts a winged helix DNA binding fold. Continuing these efforts, a second structure was also determined where the overall fold and conservation of active site residues place D212 within the PD-(D/E)XK nuclease superfamily. Notably, the structure of F112 contains an intrachain disulfide bond, prompting analysis of cysteine usage in this and other hyperthermophilic viral genomes. The analysis supports a general abundance of disulfide bonds in the intracellular proteins of hyperthermophilic viruses and the evolutionary implications of such distribution are discussed. Here we review and describe our progress towards understanding these viruses at a molecular level.