Isometrien in normierten Räumen

Ohne Zusammenfassung

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Herstellung von Analoga von Polyamin-Spinnentoxinen

Synthesis of Polyamine Analoga of Spider Toxins Within the last few years, polyamine toxins derived from various arthropods raised increasing interest due to their interaction with glutamate receptors of insects and invertebrates. Compounds 51 and 52 (Scheme 5) were prepared together with 53–58 to study a new pathway to Ala-, Lys-, and Gln-derived polyamine toxins according to Scheme 6.     

Untersuchung von Hochpolymeren mittels Pyrolyse-Gas-Chromatographie

Zusammenfassung Anschließend an eine frühere Arbeit [diese Z.228, 188 (1967)] und nach der gleichen Methode wurden eine Reihe von weiteren Homo- und Copolymerisaten durch Pyrolyse-Gas-Chromatographie untersucht. Es wurde dabei gefunden, daß aus Polyvinylchlorid, -alkohol, -acetat und -propionat neben den Säuren bzw. Wasser im wesentlichen aromatische Kohlenwasserstoffe entstehen. Jedoch sind auch die Unterschiede in der Zusammensetzung der Fragmente genügend groß, um die Polymerisate unterscheiden zu können. Polyvinylidenchlorid liefert bei der Pyrolyse aromatische, mehrfach chlorierte Kohlenwasserstoffe, das Copolymerisat Vinylchlorid-Vinylidenchlorid schwächer chlorierte Verbindungen, die wiederum von denen der Homopolymerisate unterschieden werden können. Aus Polystyrol entsteht hauptsächlich Styrol, daneben Benzolhomologe, Diphenyläthan und -propan, sowie etwa 20 Verbindungen mit der Formel C₁₆H₁₆= dimeres Styrol. Unter diesen ist die Hauptkomponente 1-Benzyl-2-methyl-benzocyclobuten. Polypropylen nimmt insofern eine Sonderstellung ein, als verschiedene Pyrolyse-Gas-Chromatogramme je nach Taktizität des Materials erhalten werden. Es wird gezeigt, daß die Auftrennung der bei der Fragmentierung entstehenden diastereomeren Olefine Grund für die Unterscheidbarkeit ist.

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Summary Following a preceding communication [Z. Anal. Chem.228, 188 (1967)] on the pyrolysis-gaschromatographic investigation of polymers further homo- and copolymerisates have been examined by the same method. It has been found that the fragments formed from polyvinyl chloride, alcohol, acetate and propionate besides the acids respectively water are essentially aromatic hydrocarbons. Yet, the differences in the composition of the fragments are sufficient to distinguish the Polymerisates. Polyvinylidene chloride yields aromatic, highly chlorinated hydrocarbons; the copolymerisate vinyl chloride — vinylidene chloride yields more weakly chlorinated compounds, which can be distinguished from those of the homopolymerisates. From polystyrene mainly styrene is formed, furthermore homologues of benzene, diphenylethane and -propane and about 20 compounds of the formula C₁₆H₁₆=dimeric styrene. Among these 1-benzyl-2-methyl-benzocyclobutene is the main component. Polypropylene yields different chromatograms according to the tacticity of the material. A distinction is possible by the separation of the diastereomeric olefins formed in fragmentation.

     

Cells with Manipulated Functions: New Perspectives for Cell Biology,Medicine, and Technology

Exposure to electrical fields can reversibly increase the electrical conductivity and permeability of a cell membrane, which regulates and directs the exchange of materials and information between the cell and its environment. If cell membranes (or artificial lipid membranes) are exposed to a field pulse of high intensity and short duration (ns to μs), local electrical breakdown occurs in them. This electrical breakdown is associated with a large permeability change in the membrane, which is such that substances or particles (up to the size of genes) which cannot normally permeate through the membrane, are able to traverse the membrane into the cell. The original properties of the membrane are restored within μs to min, depending on the experimental conditions and the membrane properties. Electrical breakdown in the zone of contact between the membranes of cells (or lipid vesicles), which have been made to adhere to each other by the action of weak inhomogeneous alternating electrical fields, leads to fusion of these cells with formation of a single cell having new functional characteristics. The electrical fusion method is very mild, and the yield of fused cells is high. The electrically induced fusion and entrapment of membrane-impermeable substances and genes in cells provide a new tool for the productions of a wide range of cells with manipulated functions, which could be used (or are being used) for the solution of a number of problems in cell biology, medicine and technology. The application of electrical membrane breakdown to clinical diagnostics, the development of cellular carrier systems for the selective transport of drugs to a site of action within the organism and the potential applications of electrically induced fusion for breeding salt-tolerant crop plants for converting solar energy into ethanol, for synthesizing natural materials and manipulating genes, are described.     

Strukturanalyse organischer Verbindungen

Zusammenfassung Die Möglichkeit der Anwendung physikalischer Methoden für die Strukturanalyse organischer Verbindungen wird anhand von Beispielen besprochen. IR, NMR, MS und Raman gelten als allgemeine Methoden, die für alle organischen Verbindungen Aussagen ermöglichen, während andere Verfahren (UV, ESR, ORD, CD, Röntgendiffraktometrie an Einkristallen) nur für bestimmte Verbindungsklassen anwendbar sind. Zur Auswertung der Daten wird ein Schema zur teilautomatisierten Interpretation beschrieben.

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Summary The applicability of physical methods to the structure analysis of organic compounds is discussed and several examples are given. IR, NMR, MS and Raman are of general use for all organic compounds, whereas other methods (UV, ESR, ORD, CD, X-ray diffraction at single crystals) can be applied only to certain groups of compounds. A scheme for partly automatized interpretation is described for evaluation of the data obtained.

     

Die heavisidefunktion als spezielle lösung ihrer funktionalgleichung

Ohne Zusammenfassung

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Die vorliegenden Untersuchungen waren Teil eines Votrages, den der Autor im August 1979 in Debrecen (Ungarn) auf dem Second International Symposium on Functional Equations and Inequalities hielt.     

Identification and characterization of smallest pore-forming protein in the cell wall of pathogenic <Emphasis Type="Italic">Corynebacterium urealyticum</Emphasis> DSM 7109

Background

Corynebacterium urealyticum, a pathogenic, multidrug resistant member of the mycolata, is known as causative agent of urinary tract infections although it is a bacterium of the skin flora. This pathogenic bacterium shares with the mycolata the property of having an unusual cell envelope composition and architecture, typical for the genus Corynebacterium. The cell wall of members of the mycolata contains channel-forming proteins for the uptake of solutes.

Results

In this study, we provide novel information on the identification and characterization of a pore-forming protein in the cell wall of C. urealyticum DSM 7109. Detergent extracts of whole C. urealyticum cultures formed in lipid bilayer membranes slightly cation-selective pores with a single-channel conductance of 1.75 nS in 1 M KCl. Experiments with different salts and non-electrolytes suggested that the cell wall pore of C. urealyticum is wide and water-filled and has a diameter of about 1.8 nm. Molecular modelling and dynamics has been performed to obtain a model of the pore. For the search of the gene coding for the cell wall pore of C. urealyticum we looked in the known genome of C. urealyticum for a similar chromosomal localization of the porin gene to known porH and porA genes of other Corynebacterium strains. Three genes are located between the genes coding for GroEL2 and polyphosphate kinase (PKK2). Two of the genes (cur_1714 and cur_1715) were expressed in different constructs in C. glutamicum ΔporAΔporH and in porin-deficient BL21 DE3 Omp8 E. coli strains. The results suggested that the gene cur_1714 codes alone for the cell wall channel. The cell wall porin of C. urealyticum termed PorACur was purified to homogeneity using different biochemical methods and had an apparent molecular mass of about 4 kDa on tricine-containing sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).

Conclusions

Biophysical characterization of the purified protein (PorACur) suggested indeed that cur_1714 is the gene coding for the pore-forming protein in C. urealyticum because the protein formed in lipid bilayer experiments the same pores as the detergent extract of whole cells. The study is the first report of a cell wall channel in the pathogenic C. urealyticum.