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Complexes of redox-active cyanomanganese ligandsHicks, Owen Michael January 1997 (has links)
No description available.
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Total synthesis of zaragozic acid CJones, Lyn Howard January 1998 (has links)
No description available.
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Directed Evolution of Cyanide Degrading EnzymesAbou Nader, Mary 1983- 14 March 2013 (has links)
Cyanide is acutely toxic to the environment. However, this simple nitrile is used in several industrial applications especially the mining industry. Due to its high affinity to metals, cyanide has been used for years to extract gold and other precious metals from the ore. Cyanide nitrilases are considered for the detoxification of the industrial wastewaters contaminated with cyanide. Their application in cyanide remediation promises cheaper and safer processes compared to chemical detoxification. However, application of these enzymes in industry requires improving their characteristics.
The goal of this dissertation is to better understand cyanide nitrilases, in particular the cyanide dihydratase from of Bacillus pumilus and Pseudomonas stutzeri and to improve their activity and stability. The lack of any high resolution structure of these enzymes calls for isolating or screening for mutants showing enhancement in enzyme properties.
Described first is a simple and efficient method utilizing in vivo recombination to create recombinant libraries incorporating the products of PCR amplification. This method is useful for generating large pools of randomly mutagenized clones after error-prone PCR mutagenesis. Several parameters were investigated to optimize this technique; length of homology region, vector treatment, induction time and ratio of fragment to vector.
Using error-prone PCR for random mutagenesis, several CynDpum mutants were isolated for higher catalysis at pH 7.7. Three point mutations, K93R, D172N and E327K increased the enzyme’s thermostability. The D172N mutation also increased the affinity of the enzyme for its substrate at pH 7.7 suggesting an effect on the active site. However, the A202T mutation located in the dimerization or the A surface rendered the enzyme inactive by destabilizing it. No significant effect on activity at alkaline pH was observed for any of the purified mutants.
Lastly, an important region for CynDstut activity was identified in the C-terminus. This same region increased the stability of CynDpum compared to the wild-type enzyme. Also, CynDpum-stut hybrid was found to be highly more stable than CynDpum. This same hybrid exhibited 100% activity at pH9, a pH where the parent enzyme is inactive, and retained 40% of its activity at pH 9.5 making it a true pH tolerant mutant.
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Cyanide-degrading enzymes for bioremediationBasile, Lacy Jamel 10 October 2008 (has links)
Cyanide-containing waste is an increasingly prevalent problem in today's
society. There are many applications that utilize cyanide, such as gold mining and
electroplating, and these processes produce cyanide waste with varying conditions.
Remediation of this waste is necessary to prevent contamination of soils and water.
While there are a variety of processes being used, bioremediation is potentially a more
cost effective alternative.
A variety of fungal species are known to degrade cyanide through the action of
cyanide hydratases, a specialized subset of nitrilases which hydrolyze cyanide to
formamide. Here I report on previously unknown and uncharacterized nitrilases from
Neurospora crassa, Gibberella zeae, and Aspergillus nidulans. Recombinant forms of
four cyanide hydratases from N. crassa, A. nidulans, G. zeae, and Gloeocercospora
sorghi were prepared after their genes were cloned with N-terminal hexahistidine
purification tags, expressed in Escherichia coli and purified using immobilized metal
affinity chromatography. These enzymes were compared according to their relative
specific activity, pH activity profiles, thermal stability, and ability to degrade cyanide in
the presence of high concentrations of copper and silver. Although all four were relatively similar, the N. crassa cyanide hydratase (CHT)
has the greatest thermal stability and widest pH range where activity remained above
50%. N. crassa also demonstrated the highest rate of cyanide degradation in the
presence of both metals tested. The CHT of A. nidulans and N. crassa have the highest
reaction rate of the four fungal nitrilases evaluated in this work.
These data help determine optimization conditions for the possible use of these
enzymes in the bioremediation of cyanide-containing waste. Similar to known plant
pathogenic fungi, in vivo expression of CHT in both N. crassa and A. nidulans were
induced by growth in the presence of KCN (potassium cyanide).
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The effect of activated carbon on the rate of dissolving gold by cyanideLoving, John Clyde, 1916- January 1941 (has links)
No description available.
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The reactions of methysilylcyanides with Lewis acidsWestwood, Aidan Vincent Kevin January 1990 (has links)
No description available.
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Some problems in cyanidingSchmidt, Sidney S. Caples, Russell B. January 1910 (has links) (PDF)
Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1910. / The entire thesis text is included in file. Typescript. Illustrated by authors. Sidney S. Schmidt received a Bachelor of Science in General Science. Russell B. Caples received a Bachelor of Science in Mining Engineering. Both degrees determined from "1874-1999 MSM-UMR Alumni Directory". Title from title screen of thesis/dissertation PDF file (viewed March 17, 2009) Includes bibliographical references (p. 2, 17-18).
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The cyaniding of a Mexican silver oreWilson, Homer Marvon. Griffin, Roy Watson. January 1915 (has links) (PDF)
Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1915. / The entire thesis text is included in file. Typescript. Illustrated by authors. Title from title screen of thesis/dissertation PDF file (viewed April 8, 2009)
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Gold precipitationAlexander, Raphael Curier. Gill, William Harris. January 1903 (has links) (PDF)
Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1903. / The entire thesis text is included in file. Typescript. Illustrated by authors. "1901" handwritten on title page. 1903 determined to be the year the degrees were granted from "1874-1999 MSM-UMR Alumni Directory" and "The History of Missouri School of Mines and Metallurgy" by Bonita and Clair V. Mann. Raphael C. Alexander determined to be Raphael Curier Alexander and W. H. Gill determined to be William Harris Gill from "Thirty-Third Annual Catalogue of the School of Mines and Metallurgy". Title from title screen of thesis/dissertation PDF file (viewed October 27, 2008)
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Cyaniding the Buckhorn clayCook, Paul Richardson. January 1916 (has links) (PDF)
Thesis--University of Missouri, School of Mines and Metallurgy, 1916. / The entire thesis text is included in file. Typescript. Illustrated by author. Paul R. Cook determined to be Paul Richardson Cook from "1874-1999 MSM-UMR Alumni Directory". Title from title screen of thesis/dissertation PDF file (viewed April 21, 2009)
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