Isolation and characterization of 1,4-β-glucan 4-glucanohydrolases (EC 3.2.1.4) from a technical Trichoderma viride cellulase

The following enzyme activities were detected in a Trichoderma viride cellulase (Röhm 2230 B): 1,4-β-d-glucan cellobiohydrolase (C₁), 1,4-β-d-glucan 4-glucanohydrolase (C_x), β-glucosidase, β-galactosidase, polygalacturonase, proteinase, xylanase, amylase, esterase and ‘polyphenoloxidase’. Isolation of cellulolytic enzymes was performed starting with adsorption chromatography on Avicel SF, leading to separation of more than 90% of non-cellulolytic enzymes and 96% of β-glucosidase activity (= fraction A). In fraction A, 30% of the C_x activity was determined whereas, in a separated fraction, B, the remaining C_x and the total C₁ activity was established. Further fractionation of B using ion-exchange and gel chromatography resulted in the separation of three purified enzyme fractions, PI to PIII, with endo C_x activities. Additionally, C₁ activity was found in PIII. PI-PIII were characterized by means of their pH optima, isoelectric points and molecular weights.     

Studies on flavonol degradation by peroxidase (donor: H2O2-oxidoreductase,EC 1.11.1.7): Part 1—Kaempferol

The peroxidatic degradation of kaempferol was studied at pH 5·5 under UV-spectrophotometric control. The reaction products obtained after incubation of kaempferol (dissolved in ethylene glycol monomethylether) with peroxidase (Boehringer, Mannheim)/H₂O₂ were fractionated in preparative scale by liquid chromatography on Sephadex LH-20. About twenty compounds were detected by analytical HPLC, from which four substances could be characterized by means of their spectroscopic data: 2,4,6-trihydroxybenzoic acid, 4-hydroxybenzoic acid, 2,2-dihydroxy-1(2,4,6-trihydroxyphenyl)-3(4-hydroxyphenyl)-1,3-propandione and 2-(4-methoxyphenyl)-5,7-dihydroxy-4H-1-benzopyran-4-one (acacetin).     

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Charge storage of electrospun fiber mats of poly(phenylene ether)/polystyrene blends

Nonwoven fiber mats composed of poly(phenylene ether) (PPE) and polystyrene (PS) blends were prepared by electrospinning of PPE/PS solutions in a mixture of chloroform and hexafluoroisopropanol. The blends showed higher electrospinnability and led to thinner fibers (200 nm–1.3 μm) than the pure components, because of a proper balance of electrical conductivity and interaction with the electrospinning solvent. The charge retention of the electrospun fibers was evaluated and related to the blend composition and the electret properties of the components. It was found that the nonwoven mats were able to retain up to 60% of the initial surface potential after several days of annealing at temperatures as high as 140°C, which is markedly higher than the charge retention of corona‐charged compact films. The capability of the electrospinning technique, to inject charges into the bulk of the material and to orientate the dipoles of the PPE phase in the field direction at the same time, was related to the good surface potential stability of the PPE/PS electrospun fiber mats. The possibility of creating thin PPE/PS fibers with excellent charge retention capabilities makes these materials ideal candidates for electret filter and sensing applications. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Visual modeling of RESTful conversations with RESTalk

The cost savings introduced by Web services through code reuse and integration opportunities have motivated many businesses to develop Web APIs, with ever increasing numbers opting for the REST architectural style. RESTful Web APIs are decomposed in multiple resources, which the client can manipulate through HTTP interactions with well-defined semantics. Getting the resource in the desired state might require multiple client–server interactions, what we define as a RESTful conversation. RESTful conversations are dynamically guided by hypermedia controls, such as links. Thus, when deciding whether and how to use a given RESTful service, the client might not be aware of all the interactions which are necessary to achieve its goal. This is because existing documentation of RESTful APIs describes the static structure of the interface, exposing low-level HTTP details, while little attention has been paid to conceptual, high-level, modeling of the dynamics of RESTful conversations. Low-level HTTP details can be abstracted from during the design phase of the API, or when deciding which API to use. We argue that, in these situations, visual models of the required client–server interactions might increase developers’ efficiency and facilitate their understanding. Thus, to capture all possible interaction sequences in a given RESTful conversation, we propose RESTalk, an extension to the BPMN Choreography diagrams to render them more concise and yet sufficiently expressive in the specific REST domain. We also report on the results obtained from an exploratory survey we have conducted to assess the maturity of the field for a domain-specific language and to obtain feedback for future improvements of RESTalk.     

Changes in the composition of neutral volatile components during the production of apple brandy

The changes in aroma composition during apple-brandy production have been investigated by gas chromatography and coupled gas chromatography-mass spectrometry. Quantitative determinations of 97 aroma components have shown that the aroma of unaged apple brandy is characterised by components produced as a result of the yeast fermentation and technological steps such as mashing and heating rather than by the genuine apple-aroma components. Genuine apple-aroma constituents, predominantly esters, are degraded during the mashing process and can be detected only in traces after the distillation. Distillation enhanced the concentration of ethyl esters and many of the higher alcohols, producing acetals and furane derivatives as well as damascenone, 2-methylhept-2-hepten-6-one and β-cyclocitral.     

Inhibition of membrane lipid peroxidation by a radical scavenging mechanism: a novel function for hydroxyl-containing ionophores

In the present study we show that K+/H+ hydroxyl-containing ionophores lasalocid-A (LAS) and nigericin (NIG) in the nanomolar concentration range, inhibit Fe2+-citrate and 2,2'-azobis(2-amidinopropane) dihydrochloride (ABAP)-induced lipid peroxidation in intact rat liver mitochondria and in egg phosphatidylcholine (PC) liposomes containing negatively charged lipids--dicetyl phosphate (DCP) or cardiolipin (CL)--and KCl as the osmotic support. In addition, monensin (MON), a hydroxyl-containing ionophore with higher affinity for Na+ than for K+, promotes a similar effect when NaCl is the osmotic support. The protective effect of the ionophores is not observed when the osmolyte is sucrose. Lipid peroxidation was evidenced by mitochondrial swelling, antimycin A-insensitive O2 consumption, formation of thiobarbituric acid-reactive substances (TBARS), conjugated dienes, and electron paramagnetic resonance (EPR) spectra of an incorporated lipid spin probe. A time-dependent decay of spin label EPR signal is observed as a consequence of lipid peroxidation induced by both inductor systems in liposomes. Nitroxide destruction is inhibited by butylated hydroxytoluene, a known antioxidant, and by the hydroxyl-containing ionophores. In contrast, valinomycin (VAL), which does not possess alcoholic groups, does not display this protective effect. Effective order parameters (Seff), determined from the spectra of an incorporated spin label are larger in the presence of salt and display a small increase upon addition of the ionophores, as a result of the increase of counter ion concentration at the negatively charged bilayer surface. This condition leads to increased formation of the ion-ionophore complex, the membrane binding (uncharged) species. The membrane-incorporated complex is the active species in the lipid peroxidation inhibiting process. Studies in aqueous solution (in the absence of membranes) showed that NIG and LAS, but not VAL, decrease the Fe2+-citrate-induced production of radicals derived from piperazine-based buffers, demonstrating their property as radical scavengers. Both Fe2+-citrate and ABAP promote a much more pronounced decrease of LAS fluorescence in PC/CL liposomes than in dimyristoyl phosphatidylcholine (DMPC, saturated phospholipid)-DCP liposomes, indicating that the ionophore also scavenges lipid peroxyl radicals. A slow decrease of fluorescence is observed in the latter system, for all lipid compositions in sucrose medium, and in the absence of membranes, indicating that the primary radicals stemming from both inductors also attack the ionophore. Altogether, the data lead to the conclusion that the membrane-incorporated cation complexes of NIG, LAS and MON inhibit lipid peroxidation by blocking initiation and propagation reactions in the lipid phase via a free radical scavenging mechanism, very likely due to the presence of alcoholic hydroxyl groups in all three molecules and to the attack of the aromatic moiety of LAS.     

Structure of two fragments of the third cytoplasmic loop of the rat angiotensin II AT1A receptor. Implications with respect to receptor activation and G-protein selection and coupling

Managed care is an increasingly widespread way of delivering health care that combines medical care provider systems (doctors, nurses, clinics, hospitals) with the payor system (health insurance). This article gives a historical overview of managed health care, discusses managed HIV care, and managed care reform.