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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.
1

Enantioselective synthesis and cyclisation studies of 2-hydroxy esters

Silcock, Alan J. January 1999 (has links)
No description available.
2

Studies on glutamate dehydrogenase

Engel, Paul C. January 1968 (has links)
No description available.
3

Lactate dehydrogenase : studies towards the design, synthesis and co-crystallisation of bisubstrate inhibitors

Dempster, Sally January 2013 (has links)
No description available.
4

ADH2 repression : a genetic and biochemical approach /

Voronkova, Valentina Vladimirovna, January 2002 (has links)
Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 96-104).
5

Obtenção da enzima glicose 6-fosfato desidrogenase utilizando \'Saccharomyces cerevisiae\' W303-181 / Production of glucose 6-phosphate dehydrogenase from Saccharomyces cerevisiae W303-181

Luiz Carlos Martins das Neves 24 April 2003 (has links)
A glicose 6-fosfato desidrogenase (G6PDH) é a primeira enzima do processo oxidativo da via das pentoses fosfato e apresenta diversas aplicações industriais. Foram avaliadas as influências de algumas variáveis sobre a produção de G6PDH. No Processo Descontínuo variaram-se a concentração da fonte de carbono, relação carbono-nitrogênio, concentração de aminoácidos e nucleotídeos , pH e a vazão de ar fornecida. A variação na atividade enzimática indicou que as condições do meio são importantes na obtenção desta enzima, tendo sido obtida atividade específica máxima de 86 U/g cél e produtividade de 10,5 U/L.h. No Processo Descontínuo-Alimentado variaram-se o sistema de adição e os nutrientes alimentados. A atividade específica máxima obtida foi 72 U/g cél e a produtividade foi 47 U/L.h. Os resultados indicaram o controle da concentração de glicose em 5g/L para uma melhor produtividade e a necessidade de maiores estudos a fim de otimizar o processo. / The glucose 6-phosphate dehydrogenase (G6PDH) is the first enzyme of the pentose phosphate pathway, converting glucose-6-phosphate into 6-phosphogluconate. Besides its importance in biochemistry and medical studies, this enzyme is used in several analytical methods, industrial and commercial application. In this work the influence of several variables in the production of Glucose-6-Phosphate Dehydrogenase in batch and fed-batch processes were studied. In batch cultures the variables were the glucose concentration (10 and 20 g/L), the C:N ratio (3.5 and 6.7 g/g), the aminoacids and nucleotides concentrations (10 and 20 mg/L), pH (4.6 and 5.7) and the aeration (0, 0.8, 1.7 and 2.2 vvm). It was observed that the G6PDH activity varied according to the conditions of the culture. Specific Activity value of 86 U/g cell and productivity of 10,5 U/L.h were attained when the test was carried out as follows: 30oC, pH 5.7, 400 rpm, 2.2 vvm, C:N ratio of 6.7, glucose concentration of 10 g/L, aminoacids (Tryptophan and Hystidine) and nucleotides (Adenine and Uracil) concentrations of 20 mg/L. Nevertheless, the fed-batch process was more efficient and productive than the batch process. The productivity obtained in the best fed-batch condition (glucose addition by an increasing exponential mode) was 47 U/L.h, more than four folds the productivity of the batch culture. So that, by maintaining the glucose concentration in the medium below 5 g/L, the productivity should be improved. However, more studies are needed for optimizing the G6PDH production in a Fed-Batch process. In the fed-batch cultures the feeding conditions and kind of feeding were studied. It was observed that the best fed-batch G6PDH specific activity (72 U/g of cell when the glucose was added in a decreasing linear mode) was lower than that attained in the batch cultures.
6

Obtenção da enzima glicose 6-fosfato desidrogenase utilizando \'Saccharomyces cerevisiae\' W303-181 / Production of glucose 6-phosphate dehydrogenase from Saccharomyces cerevisiae W303-181

Neves, Luiz Carlos Martins das 24 April 2003 (has links)
A glicose 6-fosfato desidrogenase (G6PDH) é a primeira enzima do processo oxidativo da via das pentoses fosfato e apresenta diversas aplicações industriais. Foram avaliadas as influências de algumas variáveis sobre a produção de G6PDH. No Processo Descontínuo variaram-se a concentração da fonte de carbono, relação carbono-nitrogênio, concentração de aminoácidos e nucleotídeos , pH e a vazão de ar fornecida. A variação na atividade enzimática indicou que as condições do meio são importantes na obtenção desta enzima, tendo sido obtida atividade específica máxima de 86 U/g cél e produtividade de 10,5 U/L.h. No Processo Descontínuo-Alimentado variaram-se o sistema de adição e os nutrientes alimentados. A atividade específica máxima obtida foi 72 U/g cél e a produtividade foi 47 U/L.h. Os resultados indicaram o controle da concentração de glicose em 5g/L para uma melhor produtividade e a necessidade de maiores estudos a fim de otimizar o processo. / The glucose 6-phosphate dehydrogenase (G6PDH) is the first enzyme of the pentose phosphate pathway, converting glucose-6-phosphate into 6-phosphogluconate. Besides its importance in biochemistry and medical studies, this enzyme is used in several analytical methods, industrial and commercial application. In this work the influence of several variables in the production of Glucose-6-Phosphate Dehydrogenase in batch and fed-batch processes were studied. In batch cultures the variables were the glucose concentration (10 and 20 g/L), the C:N ratio (3.5 and 6.7 g/g), the aminoacids and nucleotides concentrations (10 and 20 mg/L), pH (4.6 and 5.7) and the aeration (0, 0.8, 1.7 and 2.2 vvm). It was observed that the G6PDH activity varied according to the conditions of the culture. Specific Activity value of 86 U/g cell and productivity of 10,5 U/L.h were attained when the test was carried out as follows: 30oC, pH 5.7, 400 rpm, 2.2 vvm, C:N ratio of 6.7, glucose concentration of 10 g/L, aminoacids (Tryptophan and Hystidine) and nucleotides (Adenine and Uracil) concentrations of 20 mg/L. Nevertheless, the fed-batch process was more efficient and productive than the batch process. The productivity obtained in the best fed-batch condition (glucose addition by an increasing exponential mode) was 47 U/L.h, more than four folds the productivity of the batch culture. So that, by maintaining the glucose concentration in the medium below 5 g/L, the productivity should be improved. However, more studies are needed for optimizing the G6PDH production in a Fed-Batch process. In the fed-batch cultures the feeding conditions and kind of feeding were studied. It was observed that the best fed-batch G6PDH specific activity (72 U/g of cell when the glucose was added in a decreasing linear mode) was lower than that attained in the batch cultures.
7

Investigation into the Mechanism(s) which Permit the High-Rate, Degradation of PAHS and Related Petroleum Hydrocarbons in Sequencing Batch Reactors by Attached Cells in a Controlled Mixed Bacterial Community.

Hussein, Emad Ibraheim 04 December 2006 (has links)
A stable mixed culture, deposited as ATCC 55644, previously shown to degrade petroleum hydrocarbons at relatively high concentrations was used as the source of inoculum. This culture was grown in Stanier’s minimal media, either in the presence of different concentrations of naphthalene, nitrobenzene and toluene (NNT) or naphthalene and toluene (NT) as the sole source of C and/or N. Results showed that the majority of the strains isolated from the mixed culture were able to grow in the presence of NNT or NT. A total of 20 different isolates were isolated from the mixed culture. Individual isolates were grown in Stanier’s minimal medium containing a single hydrocarbon as the source of carbon or carbon and nitrogen. Only one strain was found to grow solely in the presence of nitrobenzene as the source of C and N. Most of the other isolates were able to grow in the presence of naphthalene, toluene, acenaphthene, anthracene, fluoranthene and phenanthrene, n-dodecane, hexadecane, n-pentadecane, n-tetradecane, and n-octadecane. Planktonic and immobilized cells of the controlled mixed culture (ATCC 55644) were grown in separate Sequential Batch Reactors (SBR) using Stanier's media, to which naphthalene, nitrobenzene and toluene were added as the sole source of C and/or N. Biodegradation was determined by measuring the residual hydrocarbon in the SBR and the amount of trapped volatile organic carbon (VOC) and the evolved CO2. Gas chromatography data showed that immobilized cells were able to degrade NNT faster than the planktonic cells. This observation was confirmed by CO2 evolution. Over time the loading of hydrocarbon was significantly increased from a starting level of 400 ppm (Naphthalene), 100 ppm (Nitrobenzene), and 500 ppm (toluene), to a final level of 3000 ppm (Naphthalene), 400 ppm (Nitrobenzene), and 1600 ppm (toluene). While increasing nutrient loading, the frequency of re-feeding with hydrocarbons was changed from an initial re-feeding every 60 hrs to a final re-feeding frequency of 18 hrs. The experiments clearly showed that the attached, mixed microbial community was able to effectively and rapidly degrade high concentrations of hydrocarbons. This demonstrated the practical advantages of employing attached, mixed microbial cultures in a SBR.

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