Synthesis of part of a proposed insulin second messenger glycosylinositol phosphate and the inner core of glycosylphosphatidylinositol anchors

Synthesis of 6-O-(2-amino-2-deoxy--D-glucopyranosyl)-D-myo-inositol 1-phosphate, an inner core structure found in various glycosylphosphatidylinositols, and the corresponding 1,2-cyclic phosphate, proposed as part of an insulin second messenger glycosylinositol phosphate, is described. Chirality in the inositol part of the molecule was achieved by the use of a known D-camphor acetal intermediate. The glycosylation used 4-O-allyl-2-azido-3,6-di-O-benzyl-2-deoxy--D-glucopyranosyl fluoride as glycosyl donor. The allyl group can be chemoselectively removed, opening a route to oligosaccharides bound to the 4-position of the glucosamine unit. The phosphorylation was accomplished by the phosphoramidate procedure.     

Mechanics on manifolds and the incorporation of spin into Nelson's Stochastic mechanics

Nelson's theory of universal Brownian motion is generalized to manifold-valued processes with Hamiltonian of the form H=(p–A) ²+. It is shown that a spin model of Bopp & Haag is such a process. We show that, as the radius of the sphere of this model approaches zero, we recover the Pauli equation. We analyze further the case of no external field, singling out a continuous random variable which we call the angular momentum and showing that this random variable has the quantum mechanical expectation values. We also prove an ergodic theorem to the effect that the average value of the angular momentum equals its time average along trajectories.     

Intercellular communication: the Drosophila innexin multiprotein family of gap junction proteins

Gap junctions belong to the most conserved cellular structures in multicellular organisms, from Hydra to man. They contain tightly packed clusters of hydrophilic membrane channels connecting the cytoplasms of adjacent cells, thus allowing direct communication of cells and tissues through the diffusion of ions, metabolites, and cyclic nucleotides. Recent evidence suggests that gap junctions are constructed by three different families of four transmembrane proteins: the Connexins and the Innexins found in vertebrates and in invertebrates, respectively, and the Innexin-like Pannexins, which were recently discovered in humans. This article focuses on the Drosophila Innexin multiprotein family, which is comprised of eight members. We highlight common structural features and discuss recent findings that suggest close similarities in cellular distribution, function, and regulation of Drosophila Innexins and vertebrate gap junction proteins.     

The antioxidative power AP--A new quantitative time dependent (2D) parameter for the determination of the antioxidant capacity and reactivity of different plants

In the last decade, naturally occurring antioxidants continue to play an important role in the food-supplement industry. The content of antioxidants in a plant depends on the species, temperature, humidity, period of growth, harvest month, part of the plant used and many other variables. Herein, we present a new method able to determine the all over antioxidative power (AP) of plant extracts or lyophilised plant parts based on the reducing activity against a stable test radical. The method is performed by ESR spectroscopy and is based on the well-known 1,1-diphenyl-2-picryl-hydrazil (DPPH) method with the major difference that both the antioxidative capacity and the antioxidative activity are used to characterise an antioxidant. The resulting antioxidative power is expressed in antioxidative units (AU), where 1AU corresponds to the activity of a 1 ppm solution of Vitamin C as a benchmark. This method allows a rapid, unexpensive and general applicable technique for the measurement of the antioxidative power of very different kinds of substances. The inclusion of the kinetic behaviour of the reducing process of the antioxidant for the determination of the AP allows the identification of the main antioxidant present in a sample. Herein, we present the application example of seeds, sprouts and adult parts of dandelion, amaranth, quinoa, fenugreek, broccoli, red clover and mugwort, where the AP method permits to characterise the plants with the highest antioxidant capacity and reaction velocity. The method permits to select active plant extracts for the food and nutrition industry.     

The role of melanin as protector against free radicals in skin and its role as free radical indicator in hair

Throughout the body, melanin is a homogenous biological polymer containing a population of intrinsic, semiquinone-like radicals. Additional extrinsic free radicals are reversibly photo-generated by UV and visible light. Melanin photochemistry, particularly the formation and decay of extrinsic radicals, has been the subject of numerous electron spin resonance (ESR) spectroscopy studies. Several melanin monomers exist, and the predominant monomer in a melanin polymer depends on its location within an organism. In skin and hair, melanin differs in content of eumelanin or pheomelanin. Its bioradical character and its susceptibility to UV irradiation makes melanin an excellent indicator for UV-related processes in both skin and hair. The existence of melanin in skin is strongly correlated with the prevention against free radicals/ROS generated by UV radiation. Especially in the skin melanin (mainly eumelanin) ensures the only natural UV protection by eliminating the generated free radicals/ROS. Melanin in hair can be used as a free radical detector for evaluating the efficacy of hair care products. The aim of this study was to investigate the suitability of melanin as protector of skin against UV generated free radicals and as free radical indicator in hair.     

Quantitative analysis of bacterial medium-chain-length poly([R]-3-hydroxyalkanoates) by gas chromatography

Standard chromatographic methods for the quantification of bacterial poly(3-hydroxyalkanoate) (PHA) proved to be inappropriate for the analysis of medium-chain-length PHA (mcl-PHA). Transesterification catalyzed by protic acids is not quantitative for mcl-PHA under common conditions due to slow reaction kinetics and formation of side-products in case of functionalized side-chains. To circumvent these limitations, an improved method for the quantification of mcl-PHA by GC-FID was developed. Boron trifluoride in methanol was successfully applied to quantitatively methanolyse different mcl-PHA (recovery >94%). This novel method is well-suited for the analysis of purified mcl-PHA as well as for mcl-PHA in biomass.     

Exploring Effects of Protease Choice and Protease Combinations in Enzymatic Protein Hydrolysis of Poultry By-Products

A study of the effects of single and combined protease hydrolysis on myofibrillar versus collagenous proteins of poultry by-products has been conducted. The aim was to contribute with knowledge for increased value creation of all constituents of these complex by-products. A rational approach was implemented for selecting proteases exhibiting the most different activity towards the major protein-rich constituents of mechanically deboned chicken residue (MDCR). An initial activity screening of 18 proteases on chicken meat, turkey tendons and MDCR was conducted. Based on weight yield, size exclusion chromatography (SEC) and SDS-PAGE, stem Bromelain and Endocut-02 were selected. Studies on hydrolysis of four different poultry by-products at 40 °C, evaluated by protein yield, SEC, and SDS-PAGE, indicate that the proteases’ selectivity difference can be utilized in tailor-making hydrolysates, enriched in either meat- and collagen-derived peptides or gelatin. Three modes of stem Bromelain and Endocut-02 combinations during hydrolysis of MDCR were performed and compared with single protease hydrolysis. All modes of the protease combinations resulted in a similar approximately 15% increase in product yield, with products exhibiting similar SEC and SDS-PAGE profiles. This shows that irrespective of the modes of combination, the use of more than one enzyme in hydrolysis of collagen-rich material can provide means to increase the total protein yield and ultimately contribute to increased value creation of poultry by-products.     

FTIR Spectroscopic Study of NH3 and NH3 Adsorption on Alumina-Supported Mixed Copper-Manganese Oxide Catalysts

Adsorption and coadsorption of NH₃ and NO on alumina-supported mixed copper-manganese oxide catalysts prepared from formate precursors by calcination at 670 K were studied by means of in situ FTIR spectroscopy. This revised version was published online in June 2006 with corrections to the Cover Date.     

Process Engineering for Production of Chiral Hydroxycarboxylic Acids from Bacterial Polyhydroxyalkanoates

An efficient process for the production of (R)‐hydroxycarboxylic acids (RHAs) from polyhydroxyalkanoates (PHAs) was developed. It involved the synthesis of PHA in bacteria, followed by bringing the culture broth directly to a pH optimal for in vivo PHA degradation, thus avoiding cell collection by centrifugation and pellet resuspension. The optimal pH was maintained to allow maximal release of RHAs. Using this process, cells having a dry weight (w) of 1.8 g · L⁻¹ and 45% (w/w) PHA exhibited a linear PHA degradation rate of about 0.059 g · L⁻¹ · h⁻¹ in the first 9 h. Concomitantly, RHAs were released with a rate of 0.057 g · L⁻¹ · h⁻¹. Further incubation of up to 15 h resulted in almost 90% (w/w) degradation of PHA. Based on this approach in combination with chemostat and a plug flow reactor a continuous process for the production of RHAs could be achieved.