Proefschrift Rijksuniversiteit Limburg Maastricht. / Met lit. opg. - Met bibliogr. - Met een samenvatting in het Nederlands.

Thèse (M.Sc.) -- Université Laval, 1997. / Bibliogr.: f. [82]-88. Publ. aussi en version électronique.

Thèse (M.Sc.) -- Université Laval, 1997. / Bibliogr.: f. 69-79. Publ. aussi en version électronique.

Proefschrift Universiteit Maastricht. / Met bibliogr., lit. opg. - Met samenvatting in het Nederlands.

The aim of this dissertation was to valorize the effect of various levels of taurine on the antioxidant status in rats body, monitor serum taurine and individual aminoacids in selectedorgans. This dissertation valorize the influence of taurine in the rats liver and brain after its application into feed mixtures. The effect of taurine was monitored on the ratio of GSH / GSSG,concentration of metallothionein and taurine. To this experiment were used 48 Wistar male rats, which were divided into eight groups (n = 6). During four weeks feed mixtures were given to these rats enriched with taurin eat a dose of 0, 1000, 1500, 2000 2500, 3000, 3500 and 4000 mg / kg / diet. Animals accepted diet and drinking water ad libitum. Average consumption of feed mixtures were 35 grams per day. Application taurine in creased concentration of taurine in the organism, which has an positive effect on antioxidant mechanisms of the organism. In deed we can not confirm that the addition of taurine in to the diet increases the concentrations of metallothionein and glutathione in the organism. In the brain was found increasing ratio of GSH / GSSG and reduced concentration of metallothionein. The other way around in the liver was reduction ratio of GSH / GSSG and increasing concentration of metallothionein.

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A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 2014. / The seemingly simple proton abstraction reactions underpin many chemical transformations including isomerization reactions and are thus of immense biological significance. Despite the energetic cost, enzyme-catalyzed proton abstraction reactions show remarkable rate enhancements. The pathways leading to these accelerated rates are numerous and on occasion partly enigmatic. The isomerization of the steroid, Δ5- androstene-3,17-dione by the human glutathione transferase A3-3 in mammals was investigated to gain insight into the mechanism. Particular emphasis was placed on the nature of the transition state, the intermediate suspected of aiding this process and the hydrogen bonds postulated to be the stabilizing forces of these transient species. Kinetics studies on Δ5-androstene-17-one, a substrate that is incapable of forming hydrogen bonds reveal that such stabilizing forces are not a requirement to explain the observed rate enhancements. The UV-Vis detection of the intermediate places this specie in the catalytic pathway while fluorescence spectroscopy is used to obtain the binding constant of the intermediate analogue equilenin. Analysis of the kinetics data in terms of the Marcus formalism indicates that the human glutathione transferase A3-3 lowers the intrinsic kinetic barrier by 3 kcal/mole. The results lead to the conclusion that this reaction proceeds through an enforced concerted mechanism in which the barrier to product formation is kinetically insignificant.

Reproduction de : Thèse de doctorat : Chimie moléculaire : Metz : 2005. / Titre provenant de l'écran-titre. Notes bibliographiques.