Tandem enzyme-catalysed reduction/cis-dihydroxylation of 2,2,2-trifluoroacetophenone: chemoenzymatic routes to new enantiopure phenol and benzylic alcohol reagents

Factors that control the competition between toluene dioxgenase-catalysed arene cis-dihydroxylation and dehydrogenase-catalysed ketone reduction have been studied, using whole cells of Pseudomonas putida UV and three alkylaryl ketones. The triol metabolite, obtained from 2,2,2-trifluoroacetophenone, has been used in the synthesis of single enantiomer chiral phenols and benzylic alcohols. Potential applications of the methylether derivatives of the chiral phenols and benzylic alcohols, as resolving agents, have been found. (c) 2007 Society of Chemical Industry.

Characterisation and biological activity of Glu(3) amino acid substituted GIP receptor antagonists

Glucose-dependent insulinotropic polypeptide (GIP) is an important gastrointestinal hormone, which regulates insulin release and glucose homeostasis, but is rapidly inactivated by enzymatic N-terminal truncation. Here we report the enzyme resistance and biological activity of several Glu(3) -substituted analogues of GIP namely; (Ala(3))GIP, (Lys(3))GIP, (Phe(3))GIP, (Trp(3))GIP and (Tyr(3))GIP. Only (Lys(3))- GIP demonstrated moderately enhanced resistance to DPP-IV (p <0.05 to p <0.01) compared to native GIP. All analogues demonstrated a decreased potency in cAMP production (EC50 1.47 to 11.02 nM; p <0.01 to p <0.001) with (Lys(3))GIP and (Phe(3))GIP significantly inhibiting GIP-stimulated cAMP production (p <0.05). In BRIN-BD11 cells, (Lys(3))GIP, (Phe(3))GIP, (Trp(3))GIP and (Tyr(3))- GIP did not stimulate insulin secretion with both (Lys(3))GIP and (Phe(3))GIP significantly inhibiting GIP-stimulated insulin secretion (p <0.05). Injection of each GIP analogue together with glucose in oblob mice significantly increased the glycaemic excursion compared to control (p <0.05 to p <0.001). This was associated with lack of significant insulin responses. (Ala(3))GIP, (Phe(3))GIP and (Tyr(3))GIP, when administered together with GIP, significantly reduced plasma insulin (p <0.05 top <0.01) and impaired the glucose-lowering ability (p <0.05 to p <0.01) of the native peptide. The DPP-IV resistance and GIP antagonism observed were similar but less pronounced than (Pro(3))GIP. These data demonstrate that position 3 amino acid substitution of GIP with (Ala(3)), (Phe(3)), (Tyr(3)) or (Pro(3)) provides a new class of functional GIP receptor antagonists. (C) 2007 Elsevier Inc. All rights reserved.

Steric effects in the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol using an Ir/C catalyst

The liquid phase selective hydrogenation of cinnamaldehyde to cinnamyl alcohol has been carried out over a graphite-supported iridium catalyst. The effect of reaction parameters such as temperature, pressure, concentration of reactant, the effect of addition of product to the feed and pre-reduction of the catalyst were studied. In situ pre-reduction of the catalyst with hydrogen had a very significant enhancing effect on the conversion of cinnamaldehyde and selectivity of the catalyst to cinnamyl alcohol. Kinetic analysis of the pre-reduced catalyst showed that the reaction is zero order with respect to cinnamaldehyde and first order with respect to hydrogen. The reaction follows an Arrhenius behaviour with an activation energy of 37 kJ mol(-1). Detailed analysis of the reaction showed that hydrogenation of the C=C double bond to give hydrocinnamaldehyde predominantly occurred at low conversions of cinnamaldehyde (

Substitution of pseudokinase domain residue Val-617 by large non-polar amino acids causes activation of JAK2

Explaining the uniqueness of the acquired somatic JAK2 V617F mutation, which is present in more than 95% of polycythemia vera patients, has been a challenge. The V617F mutation in the pseudokinase domain of JAK2 renders the unmutated kinase domain constitutively active. We have performed random mutagenesis at position 617 of JAK2 and tested each of the 20 possible amino acids for ability to induce constitutive signaling in Ba/F3 cells expressing the erythropoietin receptor. Four JAK2 mutants, V617W, V617M, V617I, and V617L, were able to induce cytokine independence and constitutive downstream signaling. Only V617W induced a level of constitutive activation comparable with V617F. Also, only V617W stabilized tyrosine-phosphorylated suppressor of cytokine signaling 3 ( SOCS3), a mechanism by which JAK2 V617F overcomes inhibition by SOCS3. The V617W mutant induced a myeloproliferative disease in mice, mainly characterized by erythrocytosis and megakaryocytic proliferation. Although JAK2 V617W would predictably be pathogenic in humans, the substitution of the Val codon, GTC, by TTG, the codon for Trp, would require three base pair changes, and thus it is unlikely to occur. We discuss how the predicted conformations of the activated JAK2 mutants can lead to better screening assays for novel small molecule inhibitors.

The Association Between Alcohol and Reflux Esophagitis, Barrett's Esophagus, and Esophageal Adenocarcinoma

Background & Aims: Alcohol consumption may increase gastroesophageal reflux symptoms, cause damage to the esophageal mucosa, and/or promote carcinogenesis. However, reports about the association between alcohol and reflux esophagitis, Barrett's esophagus, and esophageal adenocarcinoma are conflicting. Methods: Information relating to alcohol consumption, at age 21 and 5 years before the interview date, was collected from 230 reflux esophagitis, 224 Barrett's esophagus, and 227 esophageal adenocarcinoma patients and 260 frequency-matched population controls. Logistic regression analyses were used to compare alcohol consumption in the 3 case groups to controls with adjustment for potential confounders. Results: Population controls reporting gastroesophageal reflux symptoms were less likely than controls without symptoms to drink alcohol 5 years before the interview date (odds ratio [OR], 0.44, 0.20-0.99). No associations were observed between total alcohol consumption 5 years before the interview date and reflux esophagitis, Barrett's esophagus, or esophageal adenocarcinoma (OR, 1.26, 0.78-2.05; OR, 0.72, 0.43-1.21; and OR, 0.75, 0.46-1.22, respectively). Wine was inversely associated with reflux esophagitis (OR, 0.45, 0.27-0.75). Total alcohol consumption at age 21 years was significantly associated with reflux esophagitis (OR, 2.24, 1.35-3.74) but not with Barrett's esophagus or esophageal adenocarcinoma (OR, 1.06, 0.63-1.79 and OR, 1.27, 0.77-2.10, respectively). Conclusions: Alcohol consumption in early adulthood may lead to the development of reflux esophagitis. More recent alcohol consumption does not appear to confer any increased risk of reflux esophagitis, Barrett's esophagus, or esophageal adenocarcinoma. In fact, wine consumption may reduce the risk of these 3 esophageal disorders.

Preparation and characterization of Poly(vinyl alcohol) nanocomposites made from cellulose nanofibers

A method using a combination of ball milling, acid hydrolysis, and ultrasound was developed to obtain a high yield of cellulose nanofibers from flax fibers and microcrystalline cellulose (MCC). Poly(vinyl alcohol) (PVA) nanocomposites were prepared with these additives by a solution-casting technique. The cellulose nanofibers and nanocomposite films that were produced were characterized with Fourier transform infrared spectrometry, X- ray diffraction, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy. Nanofibers derived from MCC were on average approximately 8 nm in diameter and 111 nm in length. The diameter of the cellulose nanofibers produced from flax fibers was approximately 9 nm, and the length was 141 nm. A significant enhancement of the thermal and mechanical properties was achieved with a small addition of cellulose nanofibers to the polymer matrix. Interestingly, the flax nanofibers had the same reinforcing effects as MCC nanofibers in the matrix. Dynamic mechanical analysis results indicated that the use of cellulose nanofibers (acid hydrolysis) induced a mechanical percolation phenomenon leading to outstanding and unusual mechanical properties through the formation of a rigid filler network in the PVA matrix. X-ray diffraction showed that there was no significant change in the crystallinity of the PVA matrix with the incorporation of cellulose nanofibers. © 2009 Wiley Periodicals, Inc.

3,5-dimethyl-4-amino-1,2,4-triazole (Dat) as a tridentate ligand in the polymeric cations of [Ag-3(Dat)(2)](NO3)(3)

Colourless single crystals of [Ag-3(Dat)(2)](NO3)(3) were obtained from a reaction of silver(l) nitrate and 3,5-dimethyl-4-amino-1,2,4-triazole (Dat). In the crystal structure (orthorhombic, Fdd2, Z = 8, a = 1100.1(2), b = 3500.3(2), c = 1015.4(3) pm, R, = 0.0434) there are two crystallographically non-equivalent silver sites in a one (Ag1) to two ratio (Ag2). Both resemble linear N-Ag-N coordination although angles are 163 degrees and 144 degrees, respectively Each Dat ligand coordinates with the two ring nitrogen atoms at 216 to 219 pm and with one amino-nitrogen atom at 229 pro. According to the composition [Ag-3(Dat)(2)](3+) = [(Dat)Ag-3/2](3+), a polymeric structure is built with all Ag+ ions bridging.