Thesis (Ph.D.) --University of Montana, 2009. / Title from author supplied metadata. Description based on contents viewed on June 11, 2009. ETD number: etd-03252009-151239. Author supplied keywords: Protein Folding ; Denatured State ; Random Coil ; Aggregation ; TR-FRET. Includes bibliographical references.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009. / Committee Chair: Whetten, Robert; Committee Member: Bottomley, Lawrence; Committee Member: de Heer, Walter; Committee Member: El-Sayed, Mostafa; Committee Member: Fernandez, Facundo; Committee Member: Gordon, Sidney; Committee Member: Leavitt, Andrew; Committee Member: Orlando, Thomas. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis--University of California, Berkeley, 1959. / "Chemistry-General" Includes bibliographical references (p. ).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1976. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

No description available.

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Philosophiae Doctor - PhD / The classical approach to gene discovery has been to culture micro-organisms demonstrating a specific enzyme activity and then to recover the gene of interest through shotgun cloning. The realization that these standard microbiological methods provide limited access to the true microbial biodiversity and therefore the available microbial genetic diversity (collectively termed the Metagenome) has resulted in the development of environmental nucleic acid extraction technologies designed to access this wealth of genetic information, thereby avoiding the limitations of culture dependent genetic exploitation. In this work several gene discovery technologies was employed in an attempt to recover novel bacterial laccase genes (EC 1.10.3.2), a group of enzymes in which considerable biotechnological interest has been expressed. Metagenomic DNA extracted from two organic rich environmental samples was used as the source material for the construction of two genomic DNA libraries. The small insert plasmid based library derived from compost DNA consisted of approximately 106 clones at an average insert size of 2.7Kbp, equivalent to 2.6 Gbp of cloned environmental DNA. A Fosmid based large insert library derived from grape waste DNA consisted of approximately 44000 cfu at an average insert size of 25Kbp (1.1 Gbp cloned DNA). Both libraries were screened for laccase activity but failed to produce novel laccase genes. As an alternative approach, a multicopper oxidase specific PCR detection assay was developed using a laccase positive Streptomyces strain as a model organism. The newly designed primers were used to detect the presence of bacterial multicopper oxidases in environmental samples. This resulted in the identification of nine novel gene fragments showing identity ranging from 37 to 94% to published putative bacterial multicopper oxidase gene sequences. Three clones pMCO6, pMCO8 and pMCO9 were significantly smaller than those typically reported for bacterial laccases and were assigned to a recently described clade of Streptomyces bacterial multicopper oxidases. Two PCR based techniques were employed to attempt the recovery of flanking regions for two of these genes (pMCO7 and pMCO8). The use of TAIL-PCR resulted in the recovery of 90% of the pMCO7 ORF. As an alternative approach the Vectorette™ system was employed to recover the 3’ downstream region of pMCO8. The complexity of the DNA sample proved to be a considerable technical challenge for the implementation of both these techniques. The feasibility of both these approaches were however demonstrated in principle. Finally, in an attempt to expedite the recovery of fulllength copies of these genes a subtractive hybridization magnetic bead capture technique was adapted and employed to recover a full – length putative multicopper oxidase gene from a Streptomyces strain in a proof of concept experiment. The StrepA06pMCO gene fragment was used as a ‘driver’ against fragmented Streptomyces genomic DNA (‘tester’) and resulted in the recovery of a 1215 bp open reading frame. Unexpectedly, this ORF showed only 80% identity to the StrepA06pMCO gene sequence at nucleotide level, and 48% amino acid identity to a putative mco gene derived from a Norcardioides sp JS614. / South Africa

The molecular structures of 18 Group VI organometallic compounds were determined by single crystal X-ray diffraction. Most of these complexes either contain the 'Cp'M(NO)' fragment (where Cp'=Cp(ɳ⁵-C₅H₅ ) or Cp⁻(ɳ⁵-C₅Me₅ ) ) or were derived from such compounds. The purpose of this work was to determine the structures of representative types of Group VI nitrosyl complexes and related compounds and to compare their features. Also, an effort was made to study any structural changes that accompanied reactions involving ancillary ligands. Fourteen of the structures that were determined contain a metal-nitrosyl linkage that is nearly linear in all cases. One of these compounds is the first example of a Group VI nitrosyl complex containing two different alkyl groups. The structures of two of its reaction products show that one of the alkyl groups can form a second metal to carbon bond via an orthometallation process. Five other nitrosyl alkyl complexes that were studied contain benzyl groups. In these structures, the benzyl ligands bond to the central metal atoms in ɳ²-type linkages, through both the methylene carbon and the ipso carbon atoms. In the compounds studied, this unusual mode of attachment is not influenced by the nature of other ligands on the metal or by methyl substitution on the phenyl ring. Other neutral nitrosyl complexes studied were the products of reactions involving Group VI diene compounds with acetone. Two structures are the result of similar insertion of an acetone molecule into one of the metal-diene bonds with the formation of a new metal to oxygen bond. The orientation of the diene ligands, however, is different in these structures due to steric interactions between these groups and cyclopentadienyl ligands in the complex. A third compound, produced upon prolonged reaction of the parent diene nitrosyl complex with acetone, has a trimeric structure containing bridging acetone groups and no diene ligands. Three cationic nitrosyl structures showed some small differences from the other nitrosyl complexes studied. The metal to nitrosyl linkages are nearly linear but the bond lengths are slightly different from those found in other compounds. Metal to nitrogen distances are slightly longer and nitrogen to oxygen bond lengths are slightly shorter in these cationic complexes. This observation suggests that in these cations, the metal to nitrosyl π backbonding is weaker than in other complexes. Three of the structures presented were not derivatives of nitrosyl containing complexes. One of the compounds was isolated upon oxidation of a dioxoalkyltungsten complex. Its structure is a rare example of an organometallic oxo peroxo complex. Reaction of this product with tetracyanoethylene gave a charge-transfer complex; structural studies of this compound identified a 2:1 organometallic:TCNE complex with interactions involving the peroxo groups of the organometallic molecules and the central ethylene carbon atoms of the TCNE molecule. Treatment of a dioxoalkyltungsten complex with a substituted isocyanate did not give the anticipated diamido compound. Instead, the starting complex reacted with three isocyanate molecules; the structure of the product is essentially that of a solvated diamido complex, with one amido group and a substituted urea ligand. In the nitrosyl complexes studied, a range of ancillary ligands (alkyl groups such as trimethylsilylmethyl, triphenylethyl, benzyl; diene ligands; chloro or acetonitrile groups) does not alter the linear nature of the metal-nitrosyl fragment. In all cases, the nitrosyl group is attached to the metal centre through only the nitrogen atom and the M-N-O bond angle does not deviate significantly from 180°. / Science, Faculty of / Chemistry, Department of / Graduate

Includes bibliographical references. / The geometries of the ML₅ fragments in 196 five-coordinate metal complexes (M = Ni(II), Pd(II), Pt(II), Rh(I), Ir(I); L = coordinated ligand atom) have been studied using multi-variate statistical techniques. For each molecular fragment the geometry has been precisely described by two sets of twelve non-redundant symmetry coordinates.

A thesis submitted to the Faculty of Science University of the Witwatersrand in fulfillment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 1998. / Conformational analysis of portions of functionally-active and functionally-inactive signal peptides (incorporating the wild-type and mutants thereof) has been performed using a variety of computational prediction techniques based on both statistics and molecular mechanics. Molecular mechanics conformational studies are generally plagued by the problem of combinatorial explosion; this problem was addressed with a systematic searching procedure as well as a recently developed genetic algorithm, both utilising tile ECEPP/3 force field. The genetic algorithm, in combination with a gradient minimiser, proved to be successful in finding low-energy conformations for each peptide sequence studied. Analysis was performed in both simulated hydrophobic and hydrophilic environments, under distance-constraints. The molecular mechanics results and statistical predictions generated from the study were compared With existing experimental observations. The reliability of statistical predictions proved to be dependent on prediction method; the more consistent predictions were produced by methods based on membrane proteins, as opposed to those based on globular proteins. The physical property of hydrophobicity of signal peptide sequences, explored in these statistical predictions, was determined to be an important factor in relating sequence to functional activity. Molecular mechanics calculations produced either interrupted or non interrupted a-helical secondary structures both for functionally-efficient and for functionally-inefficient signal peptides, indicating that cc-helixformation alone cannot be correlated with protein export competence. It was concluded from our overall results that both a-helicity and hydrophobicity are required for the efficient functioning of signal peptides. / AC2017