Dragon grouper nervous necrosis virus (DGNNV), a betanodavirus, is the causative agent of viral nervous necrosis (VNN) in dragon grouper (Epinephelus lanceolatus). In our study, capsid protein of DGNNV was expressed in Escherichia coli. We mutated arginines at N-termini capsid protein to investigate the role of arginines at 29-31th position. When capsid protein lost 25 amino acids at N-termini VLPs form, mutation in any two arginines at 29-31 position to alanine could the prohibit VLPs formation. Another extending three arginines at 23-25 position wouldn¡¦t increase the RNA encapsulation into VLPs. Furthermore, N-termini mutated VLPs were all RNase resistance like wt-VLPs, but the yield was distinctly less than wt-VLPs. In the single point alanine mutations, the VLPs yield of R29A was apparently higher than others (R30A and R31A). Using circular dichroism to observe the thermal denature process and thermal stability of DGNNV VLPs, we found the Tm about 60¢J of VLPs wouldn¡¦t alter even if arginines at 23-31 position were mutated. The findings suggested the VLPs of mutated arginines at 23-31 position wouldn¡¦t affect RNase resistance and thermal stability, but the yield were lower. Another, the arginines at the 30 and 31 position is more important than at 29 position for formation of VLPs.

The observation of ferromagnetism of (Ga,Mn)As by Ohno in 1998 has inspired great interest in diluted magnetic semiconductors (DMS). DMS’s features combining ferromagnetism and semiconducting make them of great potential for conceptual spintronic devices, which is a promising field of research for the emerging electronics. The practical application of DMS requires a Curie temperature well above room temperature and an intrinsic ferromagnetism. There are several types of DMS materials. The typical ones are transition-metal (TM) doped GaAs, GaN and ZnO. The TM-doped ZnO has drawn particular attention due to the observation of room temperature ferromagnetism in this system including cobalt-doped ZnO.But the origin of ferromagnetic TM-doped ZnO is still unknown after a decade’s theoretical and experimental effort on this material. In this thesis, we do the magnetic circular dichroism(MCD) and Hall measurement of high quality Cobalt-doped ZnO thin films grown by molecular beam epitaxy (MBE). Room temperature ferromagnetism is observed in these samples. Combining the data from MCD and Hall measurement, we attribute the room temperature ferromagnetism in this system to the impurity band of the doped Cobalt cations. / published_or_final_version / Physics / Master / Master of Philosophy

No description available.

Mimicking the structure and even the function of an ??-peptide with artificial chainmolecules such as ??-peptides, ??-peptides and other unnatural oligomers has shown early success.The structural similarities between natural peptides and oligoureas lead to the belief that C2-symmetric oligoureas could be a good candidate for peptidomimicry. Molecular modelingindicates that both homochiral (all monomers have the same absolute configuration) andalternate chiral (absolute configuration of the residues alternate) C2-symmetric oligoureas canform helix- and sheet-like structures in solution conditionally.Several C2-symmetric 1,2-diamines were chosen as the building blocks for the synthesisof chiral oligoureas, and all diamines except for one were prepared in lab. Homochiral andheterochiral oligoureas based on the same diamine or mixed diamines were synthesized in thesolution phase, growing a chain by adding one unit at a time to one terminus or two units at atime to both termini with 4-nitrophenoxycarbonyl (PNP)- activated and t-butoxycarbonyl (Boc)- protected diamines as the intermediates. All the chiral oligoureas were purified by eitherrecrystallization and /or column chromatography and/ or HPLC and characterized by NMR andMALDI-MS. For some oligoureas, crystal structures were obtained. Fragment condensation wasattempted to improve the efficiency of the synthesis, but this approach led to cyclized oligoureasinstead of the desired concatenated residues.Conformational studies of chiral oligoureas were done in both the solid state and thesolution state. The crystal structures of some homochiral oligoureas and some alternate chiraloligoureas indicate that both helix-like structures and extended structures exist for these C2-symmetric oligoureas. NMR and Circular Dichroism (CD) were used to study the conformationof oligoureas in solution, but the conformational study by NMR was not conclusive. CD studyshowed that these oligoureas have multiple conformations in solution and that some of theconformations are sensitive to solvents and temperature. Also, short homochiral and alternatechiral oligoureas based on trans-1,2-diaminocyclohexane (DACH) exhibit signs of cooperativebehavior in solution as gauged by a series of experiments.

Thesis (M. Sc.)--Carleton University, 1992. / Also available in electronic format on the Internet.

Thesis (Ph. D. in Chemistry)--Vanderbilt University, Dec. 2005. / Title from title screen. Includes bibliographical references.

Made available in DSpace on 2014-06-11T19:27:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-13Bitstream added on 2014-06-13T20:56:17Z : No. of bitstreams: 1 goncalesgarcia_l_me_sjrp.pdf: 353281 bytes, checksum: 6786716aa7970dd6c603e25cad2d5709 (MD5) / As atividades realizadas compreenderam a produção de cDNA utilizando primer anti-senso e RNA purificado, amplificação do gene codificador da proteína 25K do Cole latent virus (CoLV25K), purificação do fragmento amplificado, ligação em vetor de multiplicação pGEM-T, transformação em células competentes de Escherichia coli linhagem TOP 10, purificação do vetor, digestão enzimática com as enzimas Bam HI e Hind III, subclonagem no vetor de expressão pET28a, transformação em células competentes de E. coli linhagem BL21-RIL, sequenciamento do gene no vetor de expressão e expressão da proteína a 37 o C . Quando expressa a 37 ºC, a proteína, de 25 kDa, foi encontrada em sua totalidade nos corpos de inclusão. Dessa forma, a proteína foi purificada sob condição desnaturante (utilizando 8 M de uréia) e submetida à diálise para seu reenovelamento. Após o reenovelamento, a proteína foi concentrada para aproximadamente 3 mg/mL e foram realizadas medidas de dicroísmo circular, para verificar o seu conteúdo de estrutura secundária, e o espalhamento dinâmico de luz, para estimar a distribuição de tamanho das populações de partículas que estão presentes na solução. Os dados da deconvolução do experimento de dicroísmo circular indicam um percentual de 40-46% α-hélice, 12-14% folha-β, 15-22% voltas e 24-28% de outras estruturas, indicando que a proteína está estruturada; e os dados do espalhamento dinâmico de luz mostraram que a proteína encontra-se estável, monodispersa, mas apresenta um complexo de partículas que deve ser removido para que fique nas condições ideais de cristalização. Foram utilizadas também outras técnicas para tentar alcançar a solubilidade da proteína expressa: abaixando a temperatura... / The experiments performed were, the production of cDNA using anti-sense primers and purified RNA, amplification of the gene encoding the 25K protein of Cole latent virus (CoLV25K), purification of the amplified fragment, cloning in multiplication vector pGEM-T for cell transformation into competent Escherichia coli strain TOP 10, vector purification, enzymatic digestion using the enzymes Bam HI and Hind III, subcloning in expression vector pET28a, transformation into competent cells of E. coli strain BL21-RIL, sequencing of the gene cloned into the expression vector and protein expression at 37 o C. When expressed at 37 °C, the protein with a molecular mass of 25 kDa was detected in inclusion bodies. Thus, the protein was purified under denaturing conditions (using 8 M urea) and subjected to dialysis to stimulate refolding. After refolding, the protein was concentrated to approximately 3 mg / mL and the circular dichroism assay was performed to verify the content of secondary structure, and dynamic light scattering, to estimate the size distribution of particle populations which are present in solution. The data from the deconvolution of circular dichroism experiments indicate a percentage of 40-46% α-helix, 12-14% β-sheet, 15-22% turns and 24-28% of other structures, indicating a structured protein; and the data of the dynamic light scattering showed that the protein is stable, monodispersive, but forms a large complex of particles which must be separated to before crystallization experiments. Other techniques were used to solubilize the expressed protein: lowering the temperature of expression to 18 °C, using the method... (Complete abstract click electronic access below)

Orientador: Eduardo Maffud Cilli / Banca: José Roberto Ernandes / Banca: Patricia Targon Campana / Banca: Antonio José da Costa Filho / Banca: Vani Xavier de Oliveira Junior / Resumo: A diidroorotato desidrogenase é uma enzima que apresenta um papel central na biossíntese de pirimidinas e catalisa a oxidação do diidroorotato a orotato. A enzima atua durante a via "de novo" de síntese de pirimidinas e está presente em quase todos os organismos vivos. A diidroorotato desidrogenase humana (HsDHODH) pode representar um importante alvo para o tratamento de doenças hiperproliferativas e inflamatórias, já que sua inibição bloqueia a síntese de ácidos nucléicos, impedindo a sua proliferação. Esta enzima tem uma estrutura monomérica e está associada com a membrana interna das mitocôndrias pela sua extensão N-terminal. Assim, entender em detalhes como esta enzima interage com a membrana poderia elucidar um alvo seletivo para drogas antiproliferativas, antiparasíticas e imunossupressivas. Esta região está também envolvida com a catálise central da enzima, sequestrando moléculas de ubiquinona presentes na membrana, fundamentais para as reações de oxirredução feitas pela enzima. Deste modo, para um melhor entendimento destes aspectos, neste trabalho foram sintetizados, por meio da Síntese de Peptídeos em Fase Sólida (SPFS) o peptídeo Ac-GDERFYAEHLMPTLQGLLDPESAHRLAVRFTSLG-NH2, que corresponde ao microdomínio existente na porção N-terminal da HsDHODH, entre os resíduos 33 e 66. Três análogos marcados com o aminoácido paramagnético TOAC nas posições 0, 12 ou 20, além de dois análogos duplamente marcados também foram obtidos. Ambos os peptídeos com dupla marcação possuem uma cisteína ligada ao spin MTSSL na posição 35 (C-terminal) se diferenciando pela posição do segundo marcador: um contendo outra cisteína ligada ao MTSSL na posição 12 e o segundo possuindo o TOAC na posição 0 (ou N-terminal). Estes peptídeos foram estudados por técnicas... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The dihydroorotate dehydrogenase is an enzyme that has a central role on the pyrimidine biosynthesis and catalyses the oxidation of dihydrorotate to orotate. The enzyme acts on "de novo" pyrimidines nucleotides pathway and it is present in almost all the live organisms. The human dihydroorotate dehydrogenase (HsDHODH) can represent an important target for the treatment of hiperproliferative and inflammatory diseases, since its inhibition blocks the nucleic acid synthesis, which restrains the cell proliferation. This enzyme has a monomeric structure and it is associated into the inner mitochondrial membrane by the N-terminal extension. Thus, understanding in details how this enzyme interacts with the membrane could help to elucidate a selective target for antiproliferative, antineoplasic and immunosuppressive drugs. This region is also involved with the central enzyme catalysis, harboring quinones molecules that are in the membranes, which is essential for the oxidation-reduction reactions made by the HsDHODH. In this way, for a better evaluation of these aspects, in this work we synthesized through the Solid Phase Peptide Synthesis (SPPS) the peptide Ac-GDERFYAEHLMPTLQGLLDPESAHRLAVRFTSLG-NH2, which corresponds to the HsDHODH N-terminal microdomain, between the residues 33 to 66. Three analogues labeled with the paramagnetic amino acid TOAC in the positions 0, 12 or 20 and two doubly labeled analogues were also synthesized. Both doubly labeled peptides contain a MTSSL-attached cysteine residue bounded to the position 35 (C-terminus), differing by the position of the second spin label: one possessing a cysteine with MTSSL at position 12 and the other contains TOAC at position 0 (N-terminus). These peptides were studied by spectroscopy techniques in order to obtain information about... (Complete abstract click electronic access below) / Doutor

No description available.

Thesis (Ph. D.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains xv, 190 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 153-180).