Die Wirtschaft Nordkoreas 1998/99

Die Oberste Volksversammlung billigte eine Reihe von Verfassungsänderungen, darunter vor allem Artikel 33, in dem jetzt jedem nordkoreanischen Unternehmen eine eigene, gesonderte Pflicht zur Rechnungslegung vorgeschrieben wird. Beobachter in Südkorea sehen darin u.a. einen Versuch, in die Wirtschaftspolitik allmählich "chinesische Prinzipien" (d.h. "sozialistische Marktwirtschaft") einzuführen

Social infrastructure as a basis for the university's development

Сохраненная и динамично развиваемая инфраструктура университета является надежным фундаментом для создания эффективной системы социальной работы со студентами и сотрудниками, что позволяет удовлетворить их потребности в организации досуга, формировании условий для ведения здорового образа жизни, профессионального развития и дополнительных профессиональных и социальных компетенций.The University's retained and dynamically developed infrastructure is a sustainable foundation for establishing the efficient system of social work with students and staff,which allows satisfying their needs in leisure-time activities, creating conditions for keeping a healthy way of life, professional progress, and acquiring additional vocationaland social competences

Mechanism of acetaldehyde-induced deactivation of microbial lipases

<p>Abstract</p> <p>Background</p> <p>Microbial lipases represent the most important class of biocatalysts used for a wealth of applications in organic synthesis. An often applied reaction is the lipase-catalyzed transesterification of vinyl esters and alcohols resulting in the formation of acetaldehyde which is known to deactivate microbial lipases, presumably by structural changes caused by initial Schiff-base formation at solvent accessible lysine residues. Previous studies showed that several lipases were sensitive toward acetaldehyde deactivation whereas others were insensitive; however, a general explanation of the acetaldehyde-induced inactivation mechanism is missing.</p> <p>Results</p> <p>Based on five microbial lipases from <it>Candida rugosa</it>, <it>Rhizopus oryzae</it>, <it>Pseudomonas fluorescens </it>and <it>Bacillus subtilis </it>we demonstrate that the protonation state of lysine <it>ε</it>-amino groups is decisive for their sensitivity toward acetaldehyde. Analysis of the diverse modification products of <it>Bacillus subtilis </it>lipases in the presence of acetaldehyde revealed several stable products such as <it>α,β</it>-unsaturated polyenals, which result from base and/or amino acid catalyzed aldol condensation of acetaldehyde. Our studies indicate that these products induce the formation of stable Michael-adducts at solvent-accessible amino acids and thus lead to enzyme deactivation. Further, our results indicate Schiff-base formation with acetaldehyde to be involved in crosslinking of lipase molecules.</p> <p>Conclusions</p> <p>Differences in stability observed with various commercially available microbial lipases most probably result from different purification procedures carried out by the respective manufacturers. We observed that the pH of the buffer used prior to lyophilization of the enzyme sample is of utmost importance. The mechanism of acetaldehyde-induced deactivation of microbial lipases involves the generation of <it>α,β</it>-unsaturated polyenals from acetaldehyde which subsequently form stable Michael-adducts with the enzymes. Lyophilization of the enzymes from buffer at pH 6.0 can provide an easy and effective way to stabilize lipases toward inactivation by acetaldehyde.</p

Physiological relation between respiration activity and heterologous expression of selected benzoylformate decarboxylase variants in Escherichia coli

<p>Abstract</p> <p>Background</p> <p>The benzoylformate decarboxylase (BFD) from <it>Pseudomonas putida </it>is a biotechnologically interesting biocatalyst. It catalyses the formation of chiral 2-hydroxy ketones, which are important building blocks for stereoselective syntheses. To optimise the enzyme function often the amino acid composition is modified to improve the performance of the enzyme. So far it was assumed that a relatively small modification of the amino acid composition of a protein does not significantly influence the level of expression or media requirements. To determine, which effects these modifications might have on cultivation and product formation, six different BFD-variants with one or two altered amino acids and the wild type BFD were expressed in <it>Escherichia coli </it>SG13009 pKK233-2. The oxygen transfer rate (OTR) as parameter for growth and metabolic activity of the different <it>E. coli </it>clones was monitored on-line in LB, TB and modified PanG mineral medium with the Respiratory Activity MOnitoring System (RAMOS).</p> <p>Results</p> <p>Although the <it>E. coli </it>clones were genetically nearly identical, the kinetics of their metabolic activity surprisingly differed in the standard media applied. Three different types of OTR curves could be distinguished. Whereas the first type (clones expressing Leu476Pro-Ser181Thr or Leu476Pro) had typical OTR curves, the second type (clones expressing the wild type BFD, Ser181Thr or His281Ala) showed an early drop of OTR in LB and TB medium and a drastically reduced maximum OTR in modified PanG mineral medium. The third type (clone expressing Leu476Gln) behaved variable. Depending on the cultivation conditions, its OTR curve was similar to the first or the second type. It was shown, that the kinetics of the metabolic activity of the first type depended on the concentration of thiamine, which is a cofactor of BFD, in the medium. It was demonstrated that the cofactor binding strength of the different BFD-variants correlated with the differences in metabolic activity of their respective host strain.</p> <p>Conclusions</p> <p>The BFD-variants with high cofactor binding affinity (wild type, His281Ala, Ser181Thr) obviously extract thiamine from the medium and bind it tightly to the enzyme. This might explain the hampered growth of these clones. In contrast, growth of clones expressing variants with low cofactor binding affinity (Leu476His, Leu476Pro, Leu476Pro-Ser181Thr) is not impaired. Leu476Gln has an intermediate cofactor binding strength, thus, growth of its host strain depends on the specific cultivation conditions. This paper shows that slight differences of the amino acid composition can affect protein expression and cultivation and might require an adaptation of media components. Effects such as the observed are hardly foreseeable and difficult to detect in conventional screening processes. Via small scale experiments with on-line measurements in shake flasks such effects influencing the cultivation and product formation can be detected and avoided.</p

Structural analysis of a genetically encoded fret biosensor by SAXS and MD simulations

Inspired by the modular architecture of natural signaling proteins, ligand binding proteins are equipped with two fluorescent proteins (FPs) in order to obtain Förster resonance energy transfer (FRET)-based biosensors. Here, we investigated a glucose sensor where the donor and acceptor FPs were attached to a glucose binding protein using a variety of different linker sequences. For three resulting sensor constructs the corresponding glucose induced conformational changes were measured by small angle X-ray scattering (SAXS) and compared to recently published single molecule FRET results (Höfig et al., ACS Sensors, 2018). For one construct which exhibits a high change in energy transfer and a large change of the radius of gyration upon ligand binding, we performed coarse-grained molecular dynamics simulations for the ligand-free and the ligand-bound state. Our analysis indicates that a carefully designed attachment of the donor FP is crucial for the proper transfer of the glucose induced conformational change of the glucose binding protein into a well pronounced FRET signal change as measured in this sensor construct. Since the other FP (acceptor) does not experience such a glucose induced alteration, it becomes apparent that only one of the FPs needs to have a well-adjusted attachment to the glucose binding protein

Intermetallic nickel silicide nanocatalyst—A non-noble metal–based general hydrogenation catalyst

Hydrogenation reactions are essential processes in the chemical industry, giving access to a variety of valuable compounds including fine chemicals, agrochemicals, and pharmachemicals. On an industrial scale, hydrogenations are typically performed with precious metal catalysts or with base metal catalysts, such as Raney nickel, which requires special handling due to its pyrophoric nature. We report a stable and highly active intermetallic nickel silicide catalyst that can be used for hydrogenations of a wide range of unsaturated compounds. The catalyst is prepared via a straightforward procedure using SiO2 as the silicon atom source. The process involves thermal reduction of Si–O bonds in the presence of Ni nanoparticles at temperatures below 1000°C. The presence of silicon as a secondary component in the nickel metal lattice plays the key role in its properties and is of crucial importance for improved catalytic activity. This novel catalyst allows for efficient reduction of nitroarenes, carbonyls, nitriles, N-containing heterocycles, and unsaturated carbon–carbon bonds. Moreover, the reported catalyst can be used for oxidation reactions in the presence of molecular oxygen and is capable of promoting acceptorless dehydrogenation of unsaturated N-containing heterocycles, opening avenues for H2 storage in organic compounds. The generality of the nickel silicide catalyst is demonstrated in the hydrogenation of over a hundred of structurally diverse unsaturated compounds. The wide application scope and high catalytic activity of this novel catalyst make it a nice alternative to known general hydrogenation catalysts, such as Raney nickel and noble metal–based catalysts

Professionell beraten: Qualitätsentwicklungsrahmen (QER) für die Beratung in Bildung, Beruf und Beschäftigung

Der Qualitätsentwicklungsrahmen (QER) basiert auf den BeQu-Standards und dem Kompetenzprofil für Beratende. Er dient als Werkzeug für die systematische Planung, Durchführung und Begleitung der Qualitätssicherung und -entwicklung. Mit dem QER wird die Qualitätsentwicklung strukturiert eingeführt und in die tägliche Arbeit integriert. Bereits vorhandene Qualitätsansätze werden um beratungsspezifische Aspekte erweitert. Außerdem wird die Qualitätsarbeit dokumentiert und für Ratsuchende und Verantwortliche offengelegt.The quality development framework (QER) is based on the BeQu standards and the competence profile for counsellors. It is a tool for the systematic planning, implementation and supervision of quality assurance and development. QER allow a structured implementation of quality development, fully integrated in daily routine. Existing quality approaches are supplemented with counselling-specific aspects. The quality development is documented and available for review by individuals seeking counselling and guidance and for quality officers

Synthesis of Single Atom Based Heterogeneous Platinum Catalysts: High Selectivity and Activity for Hydrosilylation Reactions

Catalytic hydrosilylation represents a straightforward and atom-efficient methodology for the creation of C-Si bonds. In general, the application of homogeneous platinum complexes prevails in industry and academia. Herein, we describe the first heterogeneous single atom catalysts (SACs), which are conveniently prepared by decorating alumina nanorods with platinum atoms. The resulting stable material efficiently catalyzes hydrosilylation of industrially relevant olefins with high TON (≈105). A variety of substrates is selectively hydrosilylated including compounds with sensitive reducible and other functional groups (N, B, F, Cl). The single atom based catalyst shows significantly higher activity compared to related Pt nanoparticles