Direct electrochemistry and spectroelectrochemistry of osmium substituted horseradish peroxidase

In this contribution the substitution of the central protoporphyrin IX iron complex of horseradish peroxidase by the respective osmium porphyrin complex is described. The direct electrochemical reduction of the Os containing horseradish peroxidase (OsHRP) was achieved at ITO and modified glassy carbon electrodes and in combination with spectroscopy revealed the three redox couples Os^IIIHRP/Os^IVHRP, Os^IVHRP/Os^VHRP and Os^VHRP/Os^VIHRP. The midpoint potentials differ dependent on the electrode material used with E_1/2 (Os^III/IV) of − 0.4 V (ITO) and − 0.25 V (GC), E_1/2 (Os^IV/^V) of − 0.16 V (ITO) and + 0.10 V (GC), and E_1/2 (Os^V/VI)of + 0.18 V (ITO), respectively. Moreover, with immobilised OsHRP the direct electrocatalytic reduction of hydrogen peroxide and tert-butyl hydroperoxide was observed. In comparison to electrodes modified with native HRP the sensitivity of the OsHRP-electrode for tert-butyl hydroperoxide is higher.     

Considerations on antibody-phage display methodology

For almost 15 years phage display is being used for the selection of specific antigen-binders from artificial libraries of single chain antibodies. Filamentous phages have been developed in a way to express foreign proteins on the surface and at the same time carrying the genetic information of the surface expressed molecule within the phage capsid. This property guarantees the coupling of phenotype and genotype during phage amplification and affinity selection. The possibility to generate large antibody libraries and the simplified antibody-backbone of a single chain antibody has made antibody-phage display to a powerful tool for the development of new therapeutics against various human diseases. In this review we discuss the general principles and latest developments and applications in antibody phage display technology.     

Farbstoffidentifizierung in Lebensmitteln mittels Ionenpaarextraktion

Zusammenfassung Lebensmittel sind Vielkomponentengemische unterschiedlicher Substanzen, wobei die zum Färben verwendeten Farbstoffe durch die Matrix der Lebensmittel unterschiedlich fest adsorbiert werden können. In der vorliegenden Arbeit wird erstmals ein umfassender Analysengang zur Isolierung und Identifizierung von Lebensmittelfarbstoffen in Lebensmitteln unterschiedlicher Zusammensetzung durch Ionenpaar-Extraktion und Chromatographie beschrieben. Als Ionenpaarbildner hat sich besonders Cetylpyridiniumchlorid für Anionfarbstoffe bewährt.

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Identification of dyes in foodstuffs by ion-pair extraction

Summary Foodstuffs are multi-component mixtures of different inorganic and organic compounds. Therefore, the identification of dyes in foodstuffs is a most difficult task. A scheme of analysis is given for dyes in different foodstuffs by use of ion-pair extraction and ion-pair chromatography. Cetylpyridinium chloride has proved to be particularly advantageous for forming ion-pairs with anionic dyes.

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Dem Vorsitzenden der Farbstoffkommission der DFG, Herrn Prof. Dr. D. Schmähl, Heidelberg, zum 60. Geburtstag gewidmet

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Dem Verband der Chemischen Industrie, Fonds der Chemischen Industrie, danken wir für die gewährte Unterstützung, der Deutschen Forschungsgemeinschaft für die Gewährung einer Sachbeihilfe.     

Laccase/glucose oxidase electrode for determination of glucose

The electrode involves a layer of co-immobilized glucose oxidase and laccase in a gelatin membrane placed over a modified oxygen electrode. Hexacyanoferrate(III) is added to the samples to oxidize reductive interferents such as ascorbic acid, and the hexacyanoferrate(II) formed is re-oxidized by a laccase-catalyzed reaction. Ascorbic acid is completely eliminated up to a concentration of 20 mM in the sample.     

NMR-spektroskopische Untersuchungen zur Solvatation von Tetraphenylimidodiphosphatokomplexen der Lanthanoiden

NMR-spectroscopic Investigations on Solvation of Lanthanoide Complexes of Tetraphenylimidodiphosphate The additional coordination of solvent molecules to chelate complexes LnA₃ of rare earth ions (Ln³⁺) and tetraphenylimidodiphosphate ions (A^?) has been studied by ¹H-NMR spectroscopy. The nature of the solvent has a great influence on the spectra observed especially in the case of paramagnetic Ln³⁺ ions. In acetone as solvent TmA₃ forms a disolvate preferably. The brutto stability constants for the additional coordination of acetone as ligands by TmA₃ are β₁ = (0.013 ± 0.003) mol^?1 · l and β₂ = (0.016 ± 0.001) mol^?1 · l².