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Effect of Secondary Interactions on the Fundamental Properties of Small Molecule Models of the Diiron Hydrogenase Active SiteSingleton, Michael Lee 2010 December 1900 (has links)
The unique active site of [FeFe]-hydrogenase has inspired over 300 small molecule models derived from the classical organometallic complex, (μ-SRS-)[Fe(CO)3]2. However, no model complex has yet reproduced the hydrogen production capabilities of the enzyme. One reason for this is that the model complexes are not subject to the large number of second coordination sphere interactions that are present in the active site. This work represents two approaches to explore the importance of non-covalent interactions on the properties of small molecule models, (μ-SRS)[Fe(CO)3]2 and (μ-SRS[Fe(CO)2L]2, of the enzyme active site.
First, a series of diiron models with additional steric bulk built into the dithiolate linker that connects the two irons were synthesized. While the electron donating ability of the dithiolate is not drastically altered, as evidenced by infrared spectroscopy, variable temperature - NMR studies show that the energy barrier for certain intramolecular dynamic processes, important in modeling the enzyme active site, is significantly lowered. Electrochemical studies on the all-CO derivatives showed no significant differences in the redox properties of the sterically bulky complexes compared to complexes without added steric bulk. For substituted complexes in which CO is replaced by strong donor ligands greater electrochemical changes were observed, with some events being more accessible by up to 230 mV. One electron oxidation of the disubstituted complexes has produced a series of rare mixed-valent FeIFeII complexes. An X-ray crystal structure of one of these complexes, (μ-SCH2C(CH3)2CH2S-)[Fe(CO)2PMe3]2PF6 shows both a semi-bridging carbonyl and an open site similar to the 2-Fe subsite in the Hox state of the enzyme active site.
Another method for studying secondary interactions on the model complexes used a host-guest approach to provide an artificial protein environment. Reaction of an aryl sulfonate-containing diiron complex with natural β-cyclodextrin results in encapsulation of the model. The X-ray crystal structure of the inclusion complex, Na (μ-SCH2N(C6H4SO3-)CH2S-)[Fe(CO)3]2·2 β-cyclodextrin shows complete enclosure of the diiron model within two cyclodextrin units. Solution studies support the formation of an inclusion complex and show that the cyclodextrin is capable of producing significant redox changes to the model complex in H2O. This work has provided a new highly modifiable method for affecting change in the properties of model complexes through intermolecular interactions.
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Biomimetic synthesis of catalytic materialsVarpness, Zachary Bradley. January 2007 (has links) (PDF)
Thesis (Ph.D.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Trevor Douglas. Includes bibliographical references (leaves 208-224).
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The development, characterization, and application of a biomimetic method of enzyme immobilizationHaase, Nicholas Rudy 24 August 2012 (has links)
This dissertation describes the characterization of layer-by-layer silica and titania coatings deposited using a protamine-induced method. It was found that silica coatings were thinner and more porous than titania coatings. These coatings were functionalized by immobilizing modified Glucose oxidase during the layer-by-layer buildup. The enzyme was found to retain higher activity in silica versus titania, with full retention of activity observed in one configuration. Immobilization in both materials resulted in enhanced thermal stability and proteolytic protection. The enzyme-functionalized coatings were then modified by the immobilization of silver nanoparticles to the exterior, and this biological/inorganic composite was tested for its antimicrobial activity against E. coli and S. aureus. Against E. coli the composite worked in a synergistic fashion, showing more potent antimicrobial activity when compared to either agent used alone. The enzyme modification method was then extended to Laccase, which was immobilized to carbon nanotubes and characterized as a biocathode. Modified laccase returned a nearly two-fold higher current density versus the native enzyme. Finally, synthetic peptides were tested for their ability to adsorb to silica and titanium-oxide surfaces and subsequently deposit titanium-oxide coatings, in an effort to better understand the structure-function relationships of mineralizing peptides.
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Synthesis, characterization and property exploration of the biomimetic poly [beta]-alanine dendrimers. / CUHK electronic theses & dissertations collectionJanuary 2000 (has links)
by Mong Kwok Kong Tony. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (p. 95-101). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.
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Biomimetic integrin-specific surface to direct osteoblastic function and tissue healingPetrie, Timothy Andrew. January 2009 (has links)
Thesis (Ph.D)--Biomedical Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Andres Garcia; Committee Member: Andrew Lyon; Committee Member: Barbara Boyan; Committee Member: Johnna Temenoff; Committee Member: Todd McDevitt. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Biomimetic approaches to functional optimization of macrocyclic decapeptide gramicidin S /Wu, Xiaoming. January 2003 (has links)
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 103-107). Also available in electronic version. Access restricted to campus users.
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Redox active tyrosine residues in biomimetic beta hairpinsSibert, Robin S. January 2009 (has links)
Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2010. / Committee Chair: Bridgette Barry; Committee Member: David Collard; Committee Member: Ingeborg Schmidt-Krey; Committee Member: Jake Soper; Committee Member: Mira Josowicz. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Paper-based biochemical and chemical amplification techniques for bio-detection /Uvieghara, Mathias N., January 2007 (has links) (PDF)
Thesis (M.S.) in Biological Engineering--University of Maine, 2007. / Includes vita. Includes bibliographical references (leaves 102-106).
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Electrical and thermal interfaces for on-chip electrochemical biosensor arraysTrombly, Nicholas P. January 2006 (has links)
Thesis (M.S.)--Michigan State University. Dept. of Electrical and Computer Engineering, 2006. / Title from PDF t.p. (viewed on Nov. 20, 2008) Includes bibliographical references (p. 75-80). Also issued in print.
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Fabrication of surface micro- and nanostructures for superhydrophobic surfaces in electric and electronic applicationsXiu, Yonghao. January 2008 (has links)
Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Hess, Dennis W.; Committee Chair: Wong, C. P.; Committee Member: Breedveld, Victor; Committee Member: Koros, William J.; Committee Member: Meredith, Carson; Committee Member: Nair, Sankar. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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