Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 279-296). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 279-296). Also available on the Internet.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2006. / Dr. Allen M. Orville, Committee Chair ; Dr. Loren D. Williams, Committee Member ; Dr. Donald F. Doyle, Committee Member ; Dr. Dale E. Edmondson, Committee Member ; Dr. Giovanni Gadda, Committee Member.

No description available.

Yacon (Smallanthus sonchifolius) root products are susceptible to oxidation, reduced quality and functional properties. The optimum water blanching process for yacon root slices was determined through a central composite design with variable temperature (80-100 degrees Celsius), blanching time (2-6 min), and citric acid concentration (0.04-0.20%). Phenolics and fructooligosaccharides of yacon slices were also evaluated after blanching. Yacon slices (3-4 mm) blanched at 90 degrees Celsius, 3.9 to 4.1min, and 0.05% to 0.07% citric acid showed the lowest polyphenol oxidase activity, highest whiteness value, and the highest sensory appearance scores. A second experiment showed that blanching at 100 degrees Celsius with 0.07% citric acid can maintain higher chlorogenic acid (3.52 mg/g more), inulin (5.41% more), and total sugar (34.9%) in yacon slices than blanching without citric acid. Thus, addition of less than 0.1% citric acid to boiling water can minimize loss of functional components of yacon slices during blanching.

No description available.

In 1972, Bergman reported cycloaromatization via 1,4- benzenoid diradicals of enediyne systems. Since 1985, five enediyne fungal products with anticancer antibiotic activity have been structurally elucidated, namely, neocarzinostatin chromophore, the calicheamicins, the esperamicins, the dynemicins, and kedarcidin chromophore. These compounds are delivered to DNA by a targeting mechanism and upon activation undergo a series of reactions which results in the generation of radicals via Bergman or Myers cyclization. Myers cyclization is aromatization of certain enynylallenes to Q,3-dehydro toluene diradicals. These radicals then abstract hydrogen atoms from DNA resulting in strand cleavage. The goal of my research project is the synthesis of enediynylacridans s~ch as 3,6-bisdimethylamino-9-[3-(2- ethynylphenyl)prop-2-ynyl]acridan which potentially have the same type of anticancer antibiotic activity as the natural products. Oxidation of the acridan (dihydro acridine) to the acridine would induce base catalyzed propargyl-allenyl isomerization. This would serve as the triggering device which leads to Myers cyclization and thus the diradical. The acridine portion of the molecule would also serve as the delivery system, as acridines are known to interact with DNA via intercalation. There is also interest in determining to what extent an N-oxide functionality would accelerate the Myers cyclization due to the incipient nitroxide radical. Another area of interest involves chemical oxidation of the acridans to the acridines. / Master of Science

Nitrochemicals are widely used as explosives, biocides and drugs. In addition, 3-nitro-tyrosine and other nitrated protein residues are important markers for many cardiovascular, neurodegenerative, and malignant conditions. Because of the wide presence of the nitrocompounds as toxins, potential nitrogen/carbon sources, and metabolic intermediates, different organisms have evolved to produce enzymes that can biodegrade nitrocompounds. The structural studies of the enzymes, which catalyze the removal of nitro group from nitrochemicals, are of considerable interest for both applied and fundamental reasons. The insights into the reaction mechanism of these enzymes can be used for designing efficient biocatalysts for bioremediation and for developing antibiotics for disease resistant microbes. Nitroalkane oxidase (NAO) produced by

Copy of author's previously published article inserted. Bibliography: leaves 180-195. Investigation of the contribution of polyphenol oxidase (PPO) and peroxidase (POD) to enzymic browning in sugarcane juice.

X-ray crystallography provides detailed information of the atomic structure of macromolecules that aides in the understanding of their molecular function. In this study, the three-dimensional structures of the Toluene-4-monooxygenase catalytic effector protein (T4moD), NAD(P)H oxidase and choline oxidase were determined. The structures of wild-type and two mutant isoforms of T4moD were solved up to 1.7 resolution. Results from the crystallographic studies indicate that there are significant differences between the X-ray structure and the structure previously solved by NMR. The high-resolution structures have helped to define the potential differences in electrostatic surfaces that may govern the feasibility of protein-protein interactions and also reveal a single, well-defined cavity suitable for toluene binding that has substantial different electrostatic properties among the effector protein family members. The structure of NAD(P)H oxidase from Lactobacillus sanfranciscensis was determined to 1.8 resolution. The flavoenzyme is of considerable interest as it catalyzes the oxidation of two equivalents of NAD(P)H and reduces one equivalent of oxygen to yield two equivalents of water without releasing hydrogen peroxide from the active site. The structure reveals the presence of a redox active cysteine residue that exists as a sulfenic acid and plays an important mechanistic role by reducing hydrogen peroxide to water. Additionally, a tightly bound ADP molecule was discovered in the enzyme which is hypothesized to play an important role in influencing the dual substrate specificity exhibited by the enzyme. The structure of choline oxidase from Arthrobacter globiformis was solved to 1.86 resolution. Choline oxidase catalyzes the four-electron oxidation of choline to glycine betaine via two sequential FAD-dependent reactions. The structure reveals a cavity within the active site, which is suitable for choline binding. This allows for the identification of the putative binding site for choline and residues involved in substrate-binding and catalysis. Additionally, the structure reveals a highly distorted FAD cofactor that contains a C4a-adduct that is proposed to be either an FAD-C4a-OH or FAD-C4a-O2- complex.