Selenium in biology: Facts and medical perspectives

Several decades after the discovery of setenium as an essential trace element in vertebrates approximately 20 eukaryotic and more than 15 prokaryotic selenoproteins containing the 21(st) proteinogenic amino acid, selenocysteine, have been identified, partially characterized or cloned from several species. Many of these proteins are involved in redox reactions with selenocysteine acting as an essential component of the catalytic cycle. Enzyme activities have been assigned to the glutathione peroxidase family, to the thioredoxin reductases, which were recently identified as selenoproteins, to the iodothyronine deiodinases, which metabolize thyroid hormones, and to the selenophosphate synthetase 2, which is involved in selenoprotein biosynthesis. Prokaryotic selenoproteins catalyze redox reactions and formation of selenoethers in (stress-induced) metabolism and energy production of E. coli, of the clostridial cluster XI and of other prokaryotes. Apart from the specific and complex biosynthesis of selenocysteine, selenium also reversibly binds to proteins, is incorporated into selenomethionine in bacteria, yeast and higher plants, or posttranslationally modifies a catalytically essential cysteine residue of CO dehydrogenase. Expression of individual eukaryotic selenoproteins exhibits high tissue specificity, depends on selenium availability, in some cases is regulated by hormones, and if impaired contributes to several pathological conditions. Disturbance of selenoprotein expression or function is associated with deficiency syndromes (Keshan and Kashin-Beck disease), might contribute to tumorigenesis and atherosclerosis, is altered in several bacterial and viral infections, and leads to infertility in male rodents

Energieszenarien: Konstruktion, Bewertung und Wirkung - "Anbieter" und "Nachfrager" im Dialog

Energieszenarien sind ein wesentliches Mittel zur Entscheidungsunterstützung in Politik und Wirtschaft. Für Infrastrukturentscheidungen im Energiebereich sind lange Zeiträume geltend. Daher ist eine sorgfältige Analyse möglicher "Energiezukünfte" von hoher Bedeutung. In diesem Band finden sich sowohl Beiträge von Wissenschaftlern als auch von Akteuren aus der Praxis, die sich mit Methodologie, Konstruktion und Bewertung von Energieszenarien in Gesellschaft, Politik und Wirtschaft beschäftigen

Energieszenarien: Konstruktion, Bewertung und Wirkung - "Anbieter" und "Nachfrager" im Dialog

Energieszenarien sind ein wesentliches Mittel zur Entscheidungsunterstützung in Politik und Wirtschaft. Für Infrastrukturentscheidungen im Energiebereich sind lange Zeiträume geltend. Daher ist eine sorgfältige Analyse möglicher "Energiezukünfte" von hoher Bedeutung. In diesem Band finden sich sowohl Beiträge von Wissenschaftlern als auch von Akteuren aus der Praxis, die sich mit Methodologie, Konstruktion und Bewertung von Energieszenarien in Gesellschaft, Politik und Wirtschaft beschäftigen

MICROORGANISMS AND ENZYMESFOR THE APPLICATION IN BIOSENSORS

Carbon monoxide, nitriles, amides, vinyl acetate, aldehydes and complex metalcyanides are examples of toxic compounds which we are planning to detect by means of simple types of enzyme-based biosensors, e. g. tubes, buttons, dosimeters or electrodes. Among the requirements appropriate enzymes should meet, are the ability of being coupled to a color reaction and sensitivity in the ppm concentration range. As appropriate enzymes were not available at the beginning of our work, we searched for microorganisms and are currently isolating and characterizing the enzymesofinterest from them. Apart from using these enzymes for sensing purposes weare also interested in devices which would allow a simultaneous removal of toxic compounds. Examples discussedin this article are a biological system for the detoxification of acetonitrile in HPLC waste and the use of enzymatically active paint for the improvement ofindoorair quality

Reclassification of Ubiquinone Q-10 Containing Carboxidotrophic Bacteria: Transfer of “[Pseudomonas] carboxydovorans” OM5T to Oligotropha, gen. nov., as Oligotropha carboxidovorans, comb. nov., Transfer of “[Alcaligenes] carboxydus” DSM 1086T to Carbophilus, gen. nov., as Carbophilus carboxidus, comb. nov., Transfer of “[Pseudomonas] compransoris” DSM 1231T to Zavarzinia, gen. nov., as Zavarzinia compransoris, comb. nov., and Amended Descriptions of the New Genera

Carboxidotrophic bacteria are defined on physiological grounds and characterized by the ability to grow with carbon monoxide (CO) as a sole source of carbon and energy under aerobic or, in some instances, denitrifying conditions. “[Pseudomonas] carboxydovorans”, “[Pseudomonas] compransoris” and “[Alcaligenes] carboxydus” are mesophilic Gram-negative carboxidotrophic species that require reclassification on the basis of chemotaxonomic and phylogenetic data. In order to reflect their localization within the alpha subclass of the Proteobacteria we propose the new genera Oligotropha, Carbophilus and Zavarzinia. “[Pseudomonas] carboxydovorans” should be transferred to the genus Oligotropha as Oligotropha carboxidovorans, comb. nov., “[Alcaligenes] carboxydus” should be transferred to the genus Carbophilus as Carbophilus carboxidus, comb. nov., and “[Pseudomonas] compransoris” to the genus Zavarzinia as Zavarzinia compransoris, comb. nov