Izopolarni fosfonatove analogy nukleotidu a kratkych oligonukleotidu.

The thesis concerns the chemical synthesis of novel type of isopolar, nonisosteric chiral nucleotide analogs containing alfa-hydroxyphosphonate moiety. The preparation of mentioned compounds is based on the addition reaction of phosphorous acid di- or trimesters on the carbonyl group.Summary in EnglishAvailable from STL, Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Characterisation of the cold-active alcohol dehydrogenase in a new psychrotolerant bacterium from Antarctica

Psychrophyllic and psychrotolerant bacteria have successfully colonized polar and alpine regions and are able to grow efficiently at temperatures close to zero. At the enzymatic level, these organisms have to cope with reduction of chemical reaction rate induced by low temperatures in order to maintain adequate metabolic fluxes. To enable them to survive and grow in cold environments, psychrophyllic and psychrotolerant bacteria have evolved a complex range of adaptations to all of their cellular components, including their membranes. Among proteins, these are cold-active enzymes that differ from their mesophillic counterparts, and mainly in their thermal catalytic properties. The strain MS-5, isolated from Antarctic soil on the basis of its ability to grow on sodium dodecyl sulphate as a sole source of carbon and energy has been taxonomically classified as a psychrotolerant variant of Micrococcus luteus. This identity was confirmed by the presence of menaquinone-8 in the neutral lipid fraction of MS-5, 16S rDNA analysis, antibiotic susceptibility testing, analysis of bacterial lipids and biochemical tests. However, restriction fragment length polymorphism analysis of the inter-gene spacer region of the strain MS-5 and two mesophillic M.luteus strains suggested the strain MS-5 as being a novel strain of the normally mesophillic Micrococcus luteus. M. luteus strain MS-5 responds to the lowering the growth temperature like mesophillic strains of M. luteus by increasing the ratio of anteiso- to iso- branched fatty acids. Primary alcohol dehydrogenase (1 ADH), constitutively produced by M. luteus strain MS-5, is cold-active having a half-time of the enzyme activity at 60 C less than 2 minutes. Gel zymography procedure together with kinetic measurements showed the preference of the enzyme to medium-chain alcohols. According its N-terminal sequence and catalytic properties this ADH belongs among Group I NAD+- dependent ADHs. The enzyme has been purified to electrophoretic homogeneity by four-step purification procedure with 846-fold purification. The enzyme is a homotetramer of a subunit relative molecular mass of 45,000 as determined by size-exclusion chromatography and SDS-PAGE. Isoelectric point and pH optimum of the enzyme were 4.7 and 10.5 respectively. N-terminal sequence of the enzyme (S E K V R G V V A M A K D A P V T) has 64 percen t identity to ADH-E2 from Mycobacterium tuberculosis and ADH from Streptomyces coelicolor A3. Although a genomic library of M. luteus MS-5 constructed in lambda phage was found to be representative, attempts to clone the adh gene were unsuccessfulAvailable from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Obsah a slozeni chmelovych pryskyric zateckych chmelu z pohledu jejich pivovarske hodnoty.

The development of hop resins and alfa-bitter acids contents in traditional Saaz semi-early red-bine hops is documented in the thesis within a period of the last 50 years.Summray in EnglishAvailable from STL, Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

A study of excitability and oscillations in chemical systems.

This work is focused on research of nonlinear dynamics in chemical systems, particularly excitability. The bromate-sulfiteferrocyanide reaction operated in a CSTR was chosen as a chemical pH-oscillator and excitatory providing well-reproducible results. Besides showing excitability, oscillations and bistability, this system was chosen due to its relatively simple mechanism. Preliminary experiments have demonstrated the capability of this system to provide an excitatory response to an appropriate external stimulus.Summary in EnglishAvailable from STL, Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Selektivni sorpce tezkych kovu.

The first part of the study is concerned with the sorption of free cation Ni. The following exchangers were used in the experimental study: dimethylsmine anion exchanger, oligo(ethyleneamine) anion exchanger, poly(ethyleneaminated) chitosan, bis-picolylamine anion exchanger, carbolic cation exchanger. Experimental results show that the applications of oligo(ethyleneamine) resins and poly(ethyleneaminated) chitosan in the free base form are optimal for the selective sorption of nickel. Standard weak base anion exchangers are not aplicable to the sorption of heavy metals, because they have low sorption capacities and restricted condition for the effective sorpiton. The carboxylic cation exchanger exhibits much greater sorption capacity, but this resin is not able to remove nickel from a mixture of cations selectively. Cation Mg (II) is not taken up by all anion exchangers. The presence of Mg (II) increased their sorption capacities and decreased the breakthrough levels of nickel to the filtrate. The effect of pH value was following: the increased pH value increased sorption capacities and decreased breakthrough levels. The change of the solution flow-rate was very important, because higher solution flow-rate caused the decrease of the sorption capacity and the increase of the breakthrough level. The second part of study is concerned with the sorption of heavy metals from complexes with EDTA. Copper, nickel and lead were chosen for these experiments, which were carried out on the oligo(ethyleneamine) resin with TEPA functional groups and on poly(ethyleneaminated) chitosan. Both these exchangers are capable to remove heavy metals selectively from complexes with EDTA.Poly(ethyleneaminated chitosan needs lower excess of cation Mg (II) for the effective sorption. Oligo(ethyleneamine) exchanger requires higher ratio in the feed solution, compared to chitosan. Chitosan exhibits the lower sensitivity to solution flow-rate. The cation Mg (II) is not taken up by both exchangers. Its presence increased their sorption capacities and decreased breakthrough levels. Oligo(ethyleneamine) exchanger is not able to remove chelated heavy metals from solution without the presence of Mg in the feed solution. The increased solution flow-rate decreased sorption capacities. The decrease of sorption capacity by poly(ethyleneaminated chitosan was lower than by oligo(ethyleneamine) resin. The sorption of lead was measured on poly(ethyleneaminated) chitosan. These sorptions were not effective. The sorption of Cu and Ni from the bimetallic solution was measured on poly(ethyleneaminated) chitosan. The results show higher preference of exchanger to cu than to Ni.Available from STL, Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Application of artificial neural networks for time series prediction

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Genetic study of PCB-degrading bacteria

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Vliv prisadovych a doprovodnych prvku na vlastnosti slitin Al-Si

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Pristupy k analyze a tvorbe vyrobniho programu podniku chemickeho prumyslu

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Studium vybranych prirodnich antioxidantu.

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