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Asymmetric biotransformation of certain tetralones to tetralols
Andrejch, Jan ; Poljaková, Jitka (advisor) ; Martínek, Václav (referee)
Preparation of pure enantiomers is very important part of chemical synthesis of industrially and pharmaceutically useful compounds. In recent years traditional chemical synthesis is replaced by biotransformations. Biotransformation means the use of isolated enzymes, enzymatic systems or whole cells in catalysis of chemical reactions. In comparison with chemical synthesis it has certain advantages. In this work the activity of yeast strains Saccharomyces uvarum K8, Saccharomyces cerevisiae K12, Torulopsis azyma K43, Torulopsis sphaerica K46 and Candida tropicalis K49, K51 a K52 in catalysis of reduction 6- bromo-2-tetralone, 7-hydroxy-2-tetralone and 7-methoxy-2-tetralone was studied. Products of these reductions are used in preparation of pharmaceutical drugs. Suitable conditions for biotransformations were found and it was proved that the yeast strains Saccharomyces uvarum K8 and Candida tropicalis K52 are able to produce 2- tetralones with ee greater than 90% with conversion 100% after four-hour biotransformation. This thesis is written in Czech.
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Isolation and characterization of catechol 1,2-dioxygenase of Candida tropicalis
Jechová, Jana ; Stiborová, Marie (advisor) ; Martínková, Markéta (referee)
Candida tropicalis yeast is a microorganism that possesses high tolerance for phenol and strong phenol degrading activity. This yeast is capable of utilizing phenol as the sole source of carbon and energy without formation of any secondary waste product. Catechol-1,2- dioxygenase was isolated from cytosolic fraction of this yeast by the procedure consisting of chromatography on DEAE-Sepharose and gel permeation chromatography on Sephadex G- 100. The catechol-1,2-dioxygenase was purified to homogeneity. The enzyme activity was followed by HPLC (catechol consumption and/or cis,cis-muconic acid formation). The activity profiles at different temperatures showed temperature optimum of 30řC. Kinetic characterizations were studying in different values of pH. The values of Km and Vmax of 0,52 mM and 17,2 nM/min for consumption of catechol, respectively, and 0,34 mM and 12,6 nM/min for formation of cis,cis-muconic acid, respectively, were found at optimum pH of the reaction, pH 7,6.
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Biotransformation of phenols by enzymatic systems of Candida tropicalis yeast and Comamonas testosteroni bacteria
Vilímková, Lenka ; Stiborová, Marie (advisor) ; Entlicher, Gustav (referee) ; Mareš, Jaroslav (referee)
Candida tropicalis yeast and bacteria Comamonas testosteroni have been considered to be able to metabolize phenol and utilize it as the only source of carbon and energy. In our laboratory we investigated the cytoplasmic enzymes responsible for the first and second step of phenol degradation, NADPH-dependent phenol hydroxylase of both C. tropicalis and C. testosteroni and catechol 1,2-dioxygenase of C. tropicalis. The aim of our study was to isolate and partially characterize those enzymes. Phenol hydroxylase purification consisted of preparation of cytosol from C. tropicalis yeast by fraction centrifugation, chromatography and re-chromatography on a column of DEAE Sepharose, fractionation by precipitation of the enzyme with polyethylene glycol 6000 and gel permeation chromatography on a column of Sephacryl S-300. Extracellular phenol hydroxylase of C. testosteroni was purified by fraction precipitation with polyethylene glycol 6000 and by gel permeation chromatography on 4B Sepharose and Sephacryl S-300. Catechol 1,2-dioxygenase was purified using the procedure consisting of: chromatography and re- chromatography on a column of DEAE Sepharose, lyophilization of the enzyme and gel permeation chromatography on a column of Sephadex G-100. The enzyme activity was determined by two methods: use of HPLC...
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Asymmetric biotransformation of certain tetralones to tetralols
Andrejch, Jan ; Poljaková, Jitka (advisor) ; Martínek, Václav (referee)
Preparation of pure enantiomers is very important part of chemical synthesis of industrially and pharmaceutically useful compounds. In recent years traditional chemical synthesis is replaced by biotransformations. Biotransformation means the use of isolated enzymes, enzymatic systems or whole cells in catalysis of chemical reactions. In comparison with chemical synthesis it has certain advantages. In this work the activity of yeast strains Saccharomyces uvarum K8, Saccharomyces cerevisiae K12, Torulopsis azyma K43, Torulopsis sphaerica K46 and Candida tropicalis K49, K51 a K52 in catalysis of reduction 6- bromo-2-tetralone, 7-hydroxy-2-tetralone and 7-methoxy-2-tetralone was studied. Products of these reductions are used in preparation of pharmaceutical drugs. Suitable conditions for biotransformations were found and it was proved that the yeast strains Saccharomyces uvarum K8 and Candida tropicalis K52 are able to produce 2- tetralones with ee greater than 90% with conversion 100% after four-hour biotransformation. This thesis is written in Czech.
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Isolation and characterization of catechol 1,2-dioxygenase of Candida tropicalis
Jechová, Jana ; Stiborová, Marie (advisor) ; Martínková, Markéta (referee)
Candida tropicalis yeast is a microorganism that possesses high tolerance for phenol and strong phenol degrading activity. This yeast is capable of utilizing phenol as the sole source of carbon and energy without formation of any secondary waste product. Catechol-1,2- dioxygenase was isolated from cytosolic fraction of this yeast by the procedure consisting of chromatography on DEAE-Sepharose and gel permeation chromatography on Sephadex G- 100. The catechol-1,2-dioxygenase was purified to homogeneity. The enzyme activity was followed by HPLC (catechol consumption and/or cis,cis-muconic acid formation). The activity profiles at different temperatures showed temperature optimum of 30řC. Kinetic characterizations were studying in different values of pH. The values of Km and Vmax of 0,52 mM and 17,2 nM/min for consumption of catechol, respectively, and 0,34 mM and 12,6 nM/min for formation of cis,cis-muconic acid, respectively, were found at optimum pH of the reaction, pH 7,6.
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