Thesis (M.S. - Hydrology and Water Resources) - University of Arizona. / Includes bibliographical references (leaves 91-93).

Thesis (Ph.D. 1973) from the Dept. of Physical and Inorganic Chemistry, University of Adelaide.

Thesis (Ph.D.) -- University of Adelaide, Department of Organic Chemistry, 1975.

Thesis (M.S.)--Ohio University, March, 1990. / Title from PDF t.p.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1952. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisor: Alan H. Cowley. Vita. Includes bibliographical references. Also available from UMI.

Magister Scientiae - MSc / Geobacillus pallidus RAPc8 is a thermophilic nitrile-degrading isolate, obtained from thermal sediment samples of a New Zealand hot spring. The G. pallidus RAPc8 NHase gene has been cloned and expressed in E. coli. The recombinant NHase exhibits nitrile-degrading activity at 50 °C, capable of degrading branched, linear and cyclic heteroaromatic nitrile substrates. However, no activity was found on homoaromatic nitrile substrates such as benzonitrile. In the present study, high levels of activity on benzonitrile were detected with a double mutant βF52GβF55L. Kinetic analysis on the mutant enzyme showed an 8-fold decrease in KM with benzonitrile (0.3mM) compared to acrylonitrile (2.6mM). Specificity constants (kcat/KM) of 5900 and 450 s-1.mM-1 were obtained for the double mutant on benzonitrile and acrylonitrile respectively. The amino acid residues lining the substrate channel were identified and the geometric dimensions measured. Cavity calculations revealed a 29% increase in volume and a 13% increase in inner surface area for the substrate channel of the double mutant when compared to the wild type. Surface representation of the wild type structure revealed two extended, curved channels, which are accessible to the bulk solvent from two locations in the heterodimer. The removal of the βF52may have contributed to the presence of a single channel with two opposing openings across the dimers with no internal blockage. Normal Mode Analysis calculations also indicate a higher intrinsic flexibility of the mutant relative tothe wild type enzyme. The increased flexibility within the mutant NHase could have introduced a functionally relevant aromatic substrate recognition conformation. / South Africa

Magister Scientiae - MSc / In this study G. pallidus RAPc8 NHase mutants were screened for reduced substrate inhibition compared to the wild type enzyme. Wild type and mutant enzymes were expressed and purified using hydrophobic interaction chromatography. Amidase coupled enzyme stop assays were conducted using 3-cyanopyridine as a substrate, whereas continuous enzyme kinetics were conducted using acrylonitrile as a substrate. / South Africa

Verticillium albo-atrum R. and B. isolates were separated into four strain groups based on morphological type. All isolates were tested for pathogenicity toward tomato, and an attempt was made to relate pathogenicity to morphological type. Since structural and functional differences in plants and animals are believed to be invariably associated with chemical differences, a survey of the nitrogenous constituents of the isolates was made in an attempt to relate any differences to morphological or pathologic strains. The alcohol-soluble extract from the mycelium of each isolate was investigated chromatographically for amino acids, amines, amides and peptides. The amino acids found were the same for all isolates. These were aspartic acid, glutamic acid, lysine, histidine, isoleucine, serine, valine, proline, methionine, ∝ alanine, tyrosine, threonine, glycine and one unidentified neutral compound, A. No amines, amides or peptides were detected. The amino acids, amines, amides and peptides of the ∝, β and Ȣ strains of Colletotricum lindemuthianum (Sacc. and Magn. ) Bri. and Gav. were isolated and identified using the techniques of paper chromatography for the purpose of comparison with Verticillium albo-atrum. The three Colletotricum strains contained the same amino acids as the Verticillium isolates with the exception of unknown A which was replaced by another unknown, B, common to all three Colletotricum strains indicating a definite species difference. Strain differences apparently do not occur in these two organisms in the groups of compounds studied. The effect of aeration, age of mycelium, pH of medium and carbon source on the qualitative amino acid content of isolate V3 were studied. These environmental conditions had no qualitative effect on the amino acids of the isolate. The free nucleotides of the acid-soluble extract of six representative isolates were studied using the technique of anion-exchange chromatography. Nucleotides isolated from all isolates and tentatively identified were guanosine monophosphate, guanosine diphosphate, guanosine triphosphate, cyt-idine diphosphate, uridine monophosphate, uridine diphosphate, uridine triphosphate and adenosine diphosphate. No other nucleotides were isolated. The above results indicated that if chemical dif-ferences do exist between strains, as postulated, they do not occur, In these two organisms, among the nitrogenous compounds studied, but must occur In some other class of compounds not studied in this investigation. / Science, Faculty of / Botany, Department of / Zoology, Department of / Graduate

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