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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
321

Dinâmica metabólica em Piper gaudichaudianum: estudo das etapas de ciclização estereosseletiva do ácido gaudichaudianico

Carvalho, Amanda Uliana de [UNESP] 24 January 2014 (has links) (PDF)
Made available in DSpace on 2014-12-02T11:16:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-01-24Bitstream added on 2014-12-02T11:21:04Z : No. of bitstreams: 1 000773472_20160124.pdf: 491423 bytes, checksum: ac26be3516e8bc78d9daee75666f1f79 (MD5) Bitstreams deleted on 2016-01-26T10:39:34Z: 000773472_20160124.pdf,. Added 1 bitstream(s) on 2016-01-26T10:40:10Z : No. of bitstreams: 1 000773472.pdf: 2807435 bytes, checksum: 4c681423754a3f921030656778adfc9c (MD5) / A família Piperaceae compreende aproximadamente 4000 espécies, sendo que o gênero Piper é o mais abundante. Muitas espécies desse gênero são utilizadas na medicina tradicional para o tratamento de diversas enfermidades. A ampla potencialidade biológica dessa família deve-se ao acúmulo de diferentes classes de metabólitos secundários, dentre os quais, destacam-se os derivados prenilados do ácido p-hidroxibenzoico e seus produtos ciclizados, denominados cromenos e/ou cromanos, que apresentam como característica química fundamental a presença de um anel pirano fundido a um anel benzeno. A espécie Piper gaudichaudianum em particular, apresenta em sua constituição o ácido 2-metil-2-(4’-metil-3’-pentenil)-8-(3’’-metil-2’’-butenil)-2H-1-cromeno-6-carboxílico, conhecido como ácido gaudichaudiânico, um cromeno prenilado que além de ser o metabólito majoritário em folhas e raízes dessa espécie, possui conhecida atividade tripanocida e antifúngica frente a fitopatógenos. Estudos químicos mostraram a rara presença das duas formas isoméricas naturais, ()-S e ()-R, do ácido gaudichaudiânico, durante o isolamento desse composto, despertando ainda mais o interesse na avaliação de suas etapas biossintéticas. Logo, o presente trabalho teve como principal objetivo estudar a etapa de formação dos enantiomeros, que devem ser formados durante o processo de ciclização de um intermediário geranilado derivado do ácido benzoico para a formação do anel benzopirânico. As propostas de ciclização química e enzimática foram avaliadas utilizando como precursor o ácido 3-geranil-4-hidroxi-5-(3’-metil-2’-butenil)benzoico conhecido como ácido myrsinoico A, identificado e isolado da espécie P. gaudichaudianum. Alguns testes para a avaliação da possibilidade da ciclização se dar por métodos químicos mostrou que em meio ácido e sob aquecimento não foi observada a formação do ácido gaudichaudiânico... / The Piperaceae family comprises about 4000 species, and the genus Piper is the most abundant. Many species of this genus are used in folk medicine to treat various diseases. The wide biological potential of this family is due to the accumulation of different classes of secondary metabolites, among which stand out the prenylated derivatives of p-hydroxybenzoic acid and its cyclized products, known as chromenes and/or chromanes, which are characterized by the presence of a pyran ring fused with a benzene moieity. Piper gaudichaudianum, in particular, presents in its constitution the 2-methyl -2-(4'-methyl-3'-pentenyl)-8-(3''-methyl-2-butenyl)-2H-1-chromene-6-carboxylic acid, known as gaudichaudianic acid, a prenylated chromene that is the major metabolite in leaves and roots of this species. This compound has shown trypanocidal and antifungal activities. Chemical studies demonstrated the presence of two naturally occurring rare isomeric forms, (+)-S and (-)-R, gaudichaudianic acid, arousing the interest in further evaluations of their biosynthetic steps. Therefore, the present work aimed to study the biosynthetic pathway related to the cyclization step leading to the enantiomers of gaudichaudianic acid using prenylated benzoic acid derivatives as intermediates. The proposed chemical and enzymatic cyclizations were evaluated using as the precursor the 3-geranyl-4-hydroxy-5-(3'-methyl-2'-butenyl )benzoic acid, known as myrsinoic acid identified and isolated from P. gaudichaudianum. To evaluate the possibility of cyclization occur by chemical methods acidic media and heating conditions were used. Under these conditions the formation of gaudichaudianic acid was not observed, which shows that the cyclization may occur enzymatically, catalyzed by a cyclase-type enzyme. Enzyme assays were performed using soluble and microsomal fractions obtained from the leaves P. gaudichaudianum and using the 3-geranyl-4-hydroxy-5-(3'-methyl-2'-butenyl) benzoic...
322

Dinâmica metabólica em Piper gaudichaudianum : estudo das etapas de ciclização estereosseletiva do ácido gaudichaudianico /

Carvalho, Amanda Uliana de. January 2014 (has links)
Orientador: Maysa Furlan / Co-orientador: João Marcos Batista Junior / Banca: Isabele Rodrigues Nascimento / Banca: Silvia Noelí López / Resumo: A família Piperaceae compreende aproximadamente 4000 espécies, sendo que o gênero Piper é o mais abundante. Muitas espécies desse gênero são utilizadas na medicina tradicional para o tratamento de diversas enfermidades. A ampla potencialidade biológica dessa família deve-se ao acúmulo de diferentes classes de metabólitos secundários, dentre os quais, destacam-se os derivados prenilados do ácido p-hidroxibenzoico e seus produtos ciclizados, denominados cromenos e/ou cromanos, que apresentam como característica química fundamental a presença de um anel pirano fundido a um anel benzeno. A espécie Piper gaudichaudianum em particular, apresenta em sua constituição o ácido 2-metil-2-(4'-metil-3'-pentenil)-8-(3''-metil-2''-butenil)-2H-1-cromeno-6-carboxílico, conhecido como ácido gaudichaudiânico, um cromeno prenilado que além de ser o metabólito majoritário em folhas e raízes dessa espécie, possui conhecida atividade tripanocida e antifúngica frente a fitopatógenos. Estudos químicos mostraram a rara presença das duas formas isoméricas naturais, ()-S e ()-R, do ácido gaudichaudiânico, durante o isolamento desse composto, despertando ainda mais o interesse na avaliação de suas etapas biossintéticas. Logo, o presente trabalho teve como principal objetivo estudar a etapa de formação dos enantiomeros, que devem ser formados durante o processo de ciclização de um intermediário geranilado derivado do ácido benzoico para a formação do anel benzopirânico. As propostas de ciclização química e enzimática foram avaliadas utilizando como precursor o ácido 3-geranil-4-hidroxi-5-(3'-metil-2'-butenil)benzoico conhecido como ácido myrsinoico A, identificado e isolado da espécie P. gaudichaudianum. Alguns testes para a avaliação da possibilidade da ciclização se dar por métodos químicos mostrou que em meio ácido e sob aquecimento não foi observada a formação do ácido gaudichaudiânico... / Abstract: The Piperaceae family comprises about 4000 species, and the genus Piper is the most abundant. Many species of this genus are used in folk medicine to treat various diseases. The wide biological potential of this family is due to the accumulation of different classes of secondary metabolites, among which stand out the prenylated derivatives of p-hydroxybenzoic acid and its cyclized products, known as chromenes and/or chromanes, which are characterized by the presence of a pyran ring fused with a benzene moieity. Piper gaudichaudianum, in particular, presents in its constitution the 2-methyl -2-(4'-methyl-3'-pentenyl)-8-(3''-methyl-2-butenyl)-2H-1-chromene-6-carboxylic acid, known as gaudichaudianic acid, a prenylated chromene that is the major metabolite in leaves and roots of this species. This compound has shown trypanocidal and antifungal activities. Chemical studies demonstrated the presence of two naturally occurring rare isomeric forms, (+)-S and (-)-R, gaudichaudianic acid, arousing the interest in further evaluations of their biosynthetic steps. Therefore, the present work aimed to study the biosynthetic pathway related to the cyclization step leading to the enantiomers of gaudichaudianic acid using prenylated benzoic acid derivatives as intermediates. The proposed chemical and enzymatic cyclizations were evaluated using as the precursor the 3-geranyl-4-hydroxy-5-(3'-methyl-2'-butenyl )benzoic acid, known as myrsinoic acid identified and isolated from P. gaudichaudianum. To evaluate the possibility of cyclization occur by chemical methods acidic media and heating conditions were used. Under these conditions the formation of gaudichaudianic acid was not observed, which shows that the cyclization may occur enzymatically, catalyzed by a cyclase-type enzyme. Enzyme assays were performed using soluble and microsomal fractions obtained from the leaves P. gaudichaudianum and using the 3-geranyl-4-hydroxy-5-(3'-methyl-2'-butenyl) benzoic... / Mestre
323

QueF and QueF-like: Diverse Chemistries in a Common Fold

Bon Ramos, Adriana 10 August 2016 (has links)
The tunneling fold (T-Fold) superfamily is a small superfamily of enzymes found in organisms encompassing all kingdoms of life. Seven members have been identified thus far. Despite sharing a common three-dimensional structure these enzymes perform very diverse chemistries. QueF is a bacterial NADPH-dependent oxidoreductase that catalyzes the reduction of the nitrile group of 7-cyano-7-deazaguanine (preQ0) to a primary amine (preQ1) in the queuosine biosynthetic pathway. Previous work on this enzyme has revealed the mechanism of reaction but the cofactor binding residues remain unknown. The experiments discussed herein aim to elucidate the role of residues lysine 80, lysine 83, and arginine 125 (B. subtilis numbering) in NADPH binding. The biological role of the disulfide bond between the conserved residues cysteine 55 and cysteine 99 observed in several crystal structures is also examined. Characterization of QueF mutants K80A, K83, R125A and R125K revealed lysine 80, lysine 83 and arginine 125 are required for turnover. Further analysis of turnover rates for R125K are consistent with this residue and both lysines being involved in cofactor binding presumably by interacting with the negatively charged phosphate tail of NADPH and are therefore involved in cofactor binding. Based on bond angles and energies, the disulfide bond between Cys55 and Cys99 was characterized as non-structural. Enzyme oxidation assays were consistent with the bond serving to protect QueF against irreversible oxidation of Cys55, which would render the enzyme inactive. This is the only known example of a stress protective mechanism in the Tunneling-fold superfamily. QueF-like is an amidinotransferase found in some species of Crenarchaeota and involved in the biosynthesis of archaeosine-tRNA. The work presented here is focused on the preliminary characterization of this enzyme, including the elucidation of the natural substrate as well as the source of ammonia. The structure of the enzyme was solved and is also discussed. Substrate analysis for QueF-like indicated this enzyme is capable of binding both preQ0 and preQ0-tRNA and reacting to form a thioimide intermediate analogous to QueF but only the latter serves as a substrate for the reaction. This makes QueF-like the first example of a nucleic acid binding enzyme in the Tunneling-fold superfamily. Ammonia, glutamine and asparagine were tested as nitrogen sources and unlike most known amidotransferases, QueF-like can only use free ammonia to produce the archaeosine-tRNA product. The crystal structure of P. calidifontis QueF-like indicates the functional enzyme is a dimer of pentamers pinned together by a large number of salt bridges. The structure presents a high degree of similarity to that of QueF albeit the higher twist of the QueF-like pentamers with respect to QueF results in a more compact structure.
324

Inhibition of Xanthine oxidase by catechins for tea (Camellia sinensis)

Aucamp, Jean Pieter 27 March 2006 (has links)
Please read the abstract in the section 07back.pdf of this document. / Dissertation (MSc (Biochemistry))--University of Pretoria, 2007. / Biochemistry / unrestricted
325

Discovery and Characterization of the Proteins Involved in the Synthesis of N⁶-Threonylcarbamoyl Adenosine, a Nucleoside Modification of tRNA

Deutsch, Christopher Wayne 15 July 2016 (has links)
N6-threonylcarbamoyl adenosine (t6A) is a universally conserved tRNA modification found at position 37 of tRNAs which decode ANN codons. Structural studies have implicated its presence as a requirement for the disruption of a U-turn motif in certain tRNAs, leading to the formation of properly structured anticodon stem loop. This structure is proposed to enhance the base pairing between U36 of tRNA and A1 of the codon which aids in translational frame maintenance. Despite significant effort since its discovery in the 1970s the enzymes involved in its biosynthesis remained undiscovered. Bioinformatic analysis identified two proteins as likely candidates for t6A synthesis, YrdC and YgjD. Subsequent gene knockout experiments in yeast were consistent with their involvement in t6A biosynthesis in vivo. Furthermore, clustering between the bacterial genes ygjD, yeaZ and yjeE as well as the identification of a protein interaction network between YgjD, YeaZ, and YjeE suggested that YeaZ and YjeE might be involved in t6A biosynthesis. The genes encoding ygjD, yeaZ, yrdC and yjeE were cloned from E. coli and the recombinant protein was purified. Experiments analyzing the incorporation of [U-14C]-L-threonine and [14C]-bicarbonate (substrates previously indicated in its biosynthesis) into tRNA in the presence of these four proteins demonstrated the first reconstitution of the t6A pathway in vitro. LC-MS analysis verified the formation of t6A, and these proteins were renamed TsaD (YgjD), TsaB (YeaZ), TsaC (YrdC), and TsaE (YjeE). Biochemical characterization of this pathway suggested that the formation of t6A proceeds through an unstable threonylcarbamoyl adenosine monophosphate (TC-AMP) intermediate, which is produced by TsaC from its substrates CO2, L-threonine and ATP. To investigate this reaction in more detail a coupled assay was developed, enabling sensitive detection of turn over. TsaC is a promiscuous enzyme which readily accepts several amino acids as substrates. The formation of t6A from TC-AMP is catalyzed by TsaD, TsaB, and TsaE. Of these three proteins only TsaD is universally conserved suggesting it is the protein catalyzing the transfer of the threonylcarbamoyl moiety to A37 of tRNA. This transfer is not promiscuous as only TC-AMP serves as an efficient substrate for t6A formation. Structural investigation of these proteins are consistent with the formation of a single protein complex potentially alleviating issues with the reactivity and instability of TC-AMP.
326

Recherche d'enzymes impliquées dans la voie de biosynthèse de la carnitine chez Arabidopsis thaliana et étude préliminaire de mutants à teneur réduite en carnitine / Research for enzymes involved in the carnitine biosynthetic pathway in Arabidopsis thaliana and preliminary study of mutants with reduced carnitine content

Zhao, Yingjuan 18 March 2014 (has links)
La carnitine, un acide aminé crucial pour le transfert intracellulaire des acides gras chez les animaux et les micro-organismes, est présente chez les plantes mais son mode d'implication dans le métabolisme lipidique et dans le développement reste à déterminer. Afin d'étudier le rôle biologique de la carnitine chez Arabidopsis nous avons initié une recherche bioinformatique d'enzymes susceptibles de participer à sa synthèse dans le but d'obtenir des mutants à teneur réduite en carnitine. Des serines hydroxyméthyl transférases (SHMT), des thréonines aldolases (THA) et des aldéhydes déshydrogénases (ALDH) candidates ont été identifiées. Une recherche de mutants, soit caractérisés, soit dans les collections disponibles, ainsi qu'une approche de mutagénèse par micro-ARN artificiel ont été initiées. Ces mutants ont été étudiés sur le plan de leur teneur en carnitine, en précurseur y-butyrobétaïne, et en esters de carnitine. Les enzymes THA ne semblent pas impliquées dans la synthèse de la carnitine et si un mutant faible de SHMT1 présente une réduction de sa teneur, et de la y-butyrobétaïne, l'implication de cette protéine reste à démontrer. L'étude d'un mutant perte de fonction du gène ALDH10A8, et de mutants baisse de fonction du gène ALDH10A9, et une complémentation fonctionnelle de mutants de levure, nous ont permis de montrer que les enzymes ALDH10 sont impliquées dans la voie de biosynthèse de la carnitine en permettant la synthèse de la y-butyrobétaïne. Les mutants des protéines ALDH10, présentant des teneurs réduites en carnitine et en acyl-carnitine, sont désormais disponibles comme outil du rôle de la carnitine chez Arabidopsis. / Carnitine, a crucial amino acid for the intacellular transfer of fatty acids in animals and microorganisms, is present in plants but its mode of implication in lipid metabolism and development remains to be determined. In order to investigate the biological function of carnitine in Arabidopsis, we initiated a bioinformatic search for enzymes that could be involved in its synthesis in order to obtain mutants with a reduced carnitine content. Serine hydroxymethyl transferases (SHMT), threonine aldolase (THA) and aldehyde dehydrogenase (ALDH) were identified as candidates. A search for mutants, either characterized or in available collections ans an amiRNA mutagenesis approach were carried out. In these mutants, the y-butyrobetaine as carnitine precursor, the carnitine, and carnitine esters were quantified. The THA enzymes do not appear to be involved in the carnitine synthesis and even if a weak mutant of SHMT1 has reduced contents of carnitine and y-butyrobetaine, the involvement of this protein remains to be demonstrated. A study of a knock-out mutant of the ALDH10A8 gene, of knock-down mutants of ALDH10A9 and a functional complementation of a C. albicans ALDH mutant, has confirmed the implication of ALDH10A8 and ALDH10A9 enzymes in the synthesis of y-butyrobetaine within the cartinine biosynthesis pathway. Mutants of the ALDH10 proteins, having significantly reduced carnitine and acyl-carnitine amounts, are now available as tools for studying the role of carnitine in Arabidopsis.
327

Characterization of immediate-early and early proteins of murine cytomegalovirus synthesized in permissive and nonpermissive cells

Walker, Douglas Gordon January 1985 (has links)
The gene products produced by murine cytomegalovirus (MCMV) in infected cells prior to viral DNA synthesis are believed to control the interaction of the virus with the cells, determining whether a permissive infection results, with virus replication, or whether further virus gene expression is inhibited, resulting in a latent or abortive infection. The aim of this study was to characterize the early viral gene products that are produced in permissive and nonpermissive cells. The proteins produced in 3T3-L1 cells, permissively infected with MCMV, during the first six hours of infection (the period prior to viral DNA replication) were characterized by polyacrylamide gel electrophoresis. Ten of the proteins were classified as immediate-early (IE) and seven as early according to their time of synthesis and also according to their synthesis in the presence of actinomycin D following the reversal of a cycloheximide mediated block in protein synthesis. The estimated molecular weights ranged from 28K - 100K. The synthesis of a dominant IE protein of 100K was significantly increased, after the reversal of a cycloheximide block, compared to unenhanced conditions. The synthesis of two other major IE proteins of 96K and 89K were also significantly enhanced by this treatment. The 100K and 89K proteins partitioned with the nuclear, cytoplasmic and cytoskeletal fractions, while the 96K protein partitioned more strongly with the nuclei. These proteins were phosphorylated. The other IE proteins were synthesized in lesser amounts. The major early proteins, which had molecular weights of 39K and 36K, were also phosphorylated and were exclusively nucleus-associated. A number of the IE and early proteins had affinity for native and denatured DNA-cellulose. The same major IE and early proteins were identified in nonpermissively infected J774A.1 macrophage cells. Although 0.6% of these cells became permissively infected with MCMV and the rest appeared to be nonpermissively infected, viral DNA and late protein synthesis was not detected. The major difference between the proteins produced in 3T3-L1 cells and J774A.1 cells was the affinity of the 96K protein for denatured DNA-cellulose, which was only observed when the protein was synthesized in J774A.1 cells. The main IE and early MCMV induced proteins were also synthesized in nonpermissively infected human fibroblast cells. The only difference between the proteins produced in these cells and 3T3-L1 cells was that the 100K IE protein appeared to have a greater nuclear-affinity, when produced in the human fibroblasts, than was found when synthesized in infected 3T3-L1 cells. In conclusion, a larger number of IE and early MCMV-induced proteins were identified in infected cells than had been previously characterized. There was no evidence of restricted MCMV gene expression occurring in two different cell types that were nonpermissively infected. This appeared to indicate that, in the nonpermissive experiments described, MCMV replication was inhibited at the stage of viral DNA synthesis. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate
328

A study of tRNA biosynthesis in Escherichia coli

Chase, Randal January 1974 (has links)
Escherichia coli was grown in the presence of amino acid analogues or in the absence of required amino acids. The tRNAs. were isolated and characterized. Numerous changes were observed in the total tRNA acceptance for particular amino acids although in no instance did these changes occur for amino acids corresponding to the adverse growth condition. The isoacceptor patterns for particular labelled aminoacyl-tRNAs were determined on the anion exchanger RPC-5. Novel isoacceptor tRNAs were observed under several growth conditions. Significant changes in tRNA isoacceptor distributions were noted. In certain instances it appeared that changes in total amino acid acceptance could be explained in terms of the increased or decreased synthesis of particular tRNA isoacceptors while for other tRNAs it seemed that changes occurred in the synthesis of all isoacceptors for a particular amino acid such that the relative amounts of isoacceptors remained constant even when total amino acid acceptance changed considerably. E. coli was grown over a wide temperature range, 17°C to 44°C, and the tRNA isolated and characterized. Novel tRNA isoacceptors were observed at both high and low growth temperatures for most but not all tRNAs. It was shown that the same isoacceptors could be formed at both extremes of temperature. Preliminary results suggest that the novel isoacceptors are formed as the result of a temperature aggravation of a nutritional problem at extremes of growth temperature. One of the novel tRNA isoacceptors formed under a variety of adverse growth conditions, tRNA3[sup Val] , was purified and partially characterized. The results are consistent with tRNA3[sup Val] being an undermodified precursor of the major isoacceptor tRNA₁[sup Val]. E. coli str[sup D] was grown and the tRNA isolated and characterized. Major differences in the amino acid acceptances for several tRNAs were observed. These changes were accomplished without any significant changes in the relative isoacceptor distributions as determined by RPC-5 chromatography. Gel electrophoretic analysis was performed on tRNA from cells grown at extremes of growth temperature. Significant differences were observed in the 5S region; there was an accumulation of material in cells grown at low temperature and a decrease of material in cells grown at high temperature. / Medicine, Faculty of / Biochemistry and Molecular Biology, Department of / Graduate
329

Isolation and functional genetic analysis of Eucalyptus wood formation genes

Zhou, Honghai 30 July 2008 (has links)
Eucalyptus trees are an important source of wood and fibre. The wood (secondary xylem) of this genus is widely used for pulp and papermaking. However, our understanding of the mechanisms which control the wood formation process (xylogenesis) in Eucalyptus and other woody species is far from complete. One reason is that xylogenesis is a very complex developmental process. The major components of wood are lignin and cellulose. Many genes involved in lignin and cellulose biosynthesis have been characterized. For example, Cinnamoyl CoA reductase (CCR) and cinnamyl alcohol dehydrogenase (CAD) are two important lignin biosynthesis genes. Plant cellulose is synthesized by cellulose synthase enzymes with the aid of some other proteins, such as sucrose synthase (SuSy) and sucrose phosphate synthase (SPS). Another factor which makes it difficult to analyze the function of Eucalyptus wood formation genes in vivo, is the long generation times of Eucalyptus trees and the difficulty to obtain transgenic Eucalyptus plants. Therefore, in this study, we investigated the use of Arabidopsis thaliana as a model system for functional analysis of wood formation genes. We transformed a lignin and a cellulose biosynthesis gene isolated from Eucalyptus to wild-type and mutant genetic backgrounds of Arabidopsis in order to test our ability to modify the cell wall chemistry of Arabidopsis thaliana using tree genes. The Eucalyptus CCR (EUCCR) gene was transformed into wild-type Arabidopsis (Col-0) and irregular xylem 4 (irx4) mutant plants, in which the homolog of EUCCR is mutated. A Eucalyptus cellulose synthase gene (EgCesA1) was also transformed into irregular xylem 1 (irx1) mutant plants, in which the homolog of EgCesA1 is mutated. Transgenics were only obtained from wild-type Col-0 transformed with EUCCR and from irx1 transformed with EgCesA1. We studied the cell wall chemistry of wild-type Arabidopsis plants overexpressing the Eucalyptus CCR gene. Chemical analysis of inflorescence stems revealed the modification of lignin and cellulose content in transgenic plants. Total lignin content was increased in T2 (5%) and T3 (12%) lines as revealed by micro-Klason lignin and thioglycolic acid quantification methods, respectively. High Pressure Liquid Chromatography (HPLC) analysis revealed that cellulose content was significantly decreased (10%) in T2 transgenic plants. This suggested the reallocation of carbon from cellulose to lignin as a result of overexpression of EUCCR in transgenic plants. Interestingly, thioacidolysis analysis revealed that in T2 plants, monomethoxylated guaiacyl (G) monomer was increased (16%) and bimethoxylated syringyl (S) monomer was decreased (21%). Therefore, the S/G lignin monomer ratio was significant decreased (32%). This implied that EUCCR might be specific to G monomer biosynthesis. The results described above confirmed that Arabidopsis thaliana can be used to model the function of wood formation genes isolated from Eucalyptus. Two novel full-length Eucalyptus sucrose synthase (SuSy) genes, EgSuSy1 and EgSuSy3, and one putative pseudogene, EgSuSy2, were also isolated in this study. Degenerate PCR was used to amplify Eucalyptus SuSy fragments from cDNA and genomic DNA. 3’RACE was used to amplify the 3’ ends of two Eucalyptus SuSy genes. Genome walking was performed to obtain the 5’ ends of EgSuSy1 and EgSuSy2 whereas 5’RACE technology was used to isolate the 5’ end of EgSuSy3. However, 3’RACE analysis failed when we tried to identify the 3’ end of EgSuSy2. Sequencing results from the genome walking product of EgSuSy2 further revealed that the start codon of this gene was missing, and we hypothesize that this is a psuedogene in the Eucalyptus genome. The EgSuSy1 cDNA was 2498 bp in length with an open reading frame of 2418 bp encoding 805 amino acids with a predicted molecular mass of 92.3 kDa. The 2528 bp full-length EgSuSy3 cDNA contained the same length of open reading frame as EgSuSy1, but encoded a polypeptide with a predicted molecular mass of 92.8 kDa. The results of quantitative real-time RT-PCR, phylogenetic analysis and gene structure of the two genes revealed that both genes might be involved in cellulose biosynthesis in primary and secondary cell walls of Eucalyptus. These two genes, EgSuSy1 and EgSuSy3, could therefore be useful targets for genetic engineering of wood properties in Eucalyptus. / Dissertation (MSc)--University of Pretoria, 2008. / Genetics / unrestricted
330

Studies on coenzyme A biosynthesis and its regulation in hyperthermophiles / 超好熱菌におけるcoenzymeA生合成およびその制御に関する研究

Shimosaka, Takahiro 23 March 2021 (has links)
京都大学 / 新制・課程博士 / 博士(工学) / 甲第23230号 / 工博第4874号 / 新制||工||1761(附属図書館) / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 跡見 晴幸, 教授 森 泰生, 教授 浜地 格 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

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