Rhodopsin reconstituted into a planar-supported lipid bilayer retains photoactivity after cross-linking polymerization of lipid monomers

Transmembrane proteins (TMPs), particularly ion channels and receptors, play key roles in transport and signal transduction. Many of these proteins are pharmacologically important and therefore targets for drug discovery. TMPs can be reconstituted in planar-supported lipid bilayers (PSLBs), which has led to development of TMP-based biosensors and biochips. However, PSLBs composed of natural lipids lack the high stability desired for many technological applications. One strategy is to use synthetic lipid monomers that can be polymerized to form robust bilayers. A key question is how lipid polymerization affects TMP structure and activity. In this study, we have examined the effects of UV polymerization of bis-Sorbylphosphatidylcholine (bis-SorbPC) on the photoactivation of reconstituted bovine rhodopsin (Rho), a model G-protein-coupled receptor. Plasmon-waveguide resonance spectroscopy (PWR) was used to compare the degree of Rho incorporation and activation in fluid and poly(lipid) PSLBs. The results show that reconstitution of Rho into a supported lipid bilayer composed only of bis-SorbPC, followed by photoinduced lipid cross-linking, does not measurably diminish protein function.     

Screening of acetogenin-producing plants in Brazilian flora

The acetogenins are strongly bioactive natural compounds present in the bark, roots, leaves, and seeds of manyAnnonaceae plants. They are modified fatty acids and their cytotoxicities have been determined for different biological models including the in vitro growth inhibition of several human cancer cell lines. Very low acetogenin yield (< 0.1 g%) has been found previously in native phytobiomass, and we have now investigated the nonpredatory exploitation of the seeds as acetogenin sources characterizing the seed triacylglycerols (dominant fraction; > 90% of the whole lipid extracts) as potential valuable by-products.     

Mullite crystallization using fully hydrolyzed silica sol: the gelation temperature influence

Mullite is an aluminosilicate widely used as a structural material for high temperature applications. This paper studies the effect of the gelation temperature on the synthesis of two mullite precursors: polymeric and colloidal silica, using both in fully-hydrolyzed silica sol, derived from sodium silicate. The gels were synthesized using aqueous silicic acid and aluminum nitrate. Ethylene glycol was added into polymeric gels. Two gelation temperatures were used: 80 and 100 °C. In the polymeric precursor, the increasing of the gelation temperature caused an increase in the silica incorporation inside the mullite crystalline lattice at 1,000 °C, and it also generated an increase in the reaction extent at all calcination temperatures. In the colloidal precursors, these effects were more intense than in the polymeric precursors in terms of yield. Colloidal samples calcined at 1,250 °C crystallized cristobalite and alpha alumina in addition to mullite when they were previously gelled at 80 °C. On the other hand, the same sample gelled at 100 °C led to only crystallized mullite. The reaction extent increased by more than 20 % for colloidal samples gelled at 100 °C compared to colloidal samples gelled at 80 °C (calcined at 1,250 °C). This increase was due to the almost total incorporation of alumina and silica in the crystalline lattice of mullite.     

Etude par Résonance Magnétique Nucléaire de dioxaphosphorinanes-1,3,2 à liaison P?N extracyclique. Exemple de changement d'orientation de la liaison P?N

The ¹H NMR spectra of several 1,3,2-dioxaphosphorinanes bearing an extracyclic P? N bond have been analysed. The ³J(POCH) couplings are strongly dependent upon the orientation of the bond around the phosphorus atom. Depending upon the nature of the bonds attached to the nitrogen atom, the dioxaphosphorinane ring may adopt either a fixed chair conformation with the P? N bond in the axial or equatorial orientation, or it may be in equilibrium between two chair conformations where the P? N bond is alternately axial or equatorial. The equilibrium is fast on the NMR time scale.     

1H, 13C, 31P NMR and conformational study of 7-membered ring organophosphorus compounds. 1,3,2-dioxaphosphepanes

The ¹H, ¹³C and ³¹P NMR data of several 2-R-2-thiono-1,3-dioxa organophosphorus molecules with 7-membered rings [R = Cl, OC₆H₅, C₆H₅, CH₃, N(CH₃)₂] are reported. The conformation of the 7-membered ring is discussed by reference to the ³J(POCH) coupling constants which are compared with those observed in 6-membered 1,3,2-dioxaphosphorinanes. It is shown that caution must be exercised in using the ³J(POCH) angular dependence as a stereochemical tool. The ³¹P spin lattice relaxation times of some of these 7-membered rings have been measured and the values are discussed.     

Enantioselective Iridium‐Catalyzed Allylation of Acetylenic Ketones via 2‐Propanol‐Mediated Reductive Coupling of Allyl Acetate: C14‐C23 of Pladienolide D

Highly enantioselective catalytic reductive coupling of allyl acetate with acetylenic ketones occurs in a chemoselective manner in the presence of aliphatic or aromatic ketones. This method was used to construct C14‐C23 of pladienolide D in half the steps previously required.     

Radiative processes as a condensation phenomenon and the physical meaning of deformed canonical structures

We study the radiative corrections of QED₃ from the dual point of view and show that this process is the exact dual to the Julia–Toulouse mechanism introduced by Quevedo and Trugenberger [F. Quevedo, C.A. Trugenberger, Nucl. Phys. B 501 (1997) 143] some years ago. We discuss the physics behind this mechanism that involves condensation of topological defects. It is shown that the dual Stuckelberg mechanism is responsible for the “rank-jump” phenomenon that transforms the scalar field (dual to Maxwell in this dimensionality) into the vectorial self-dual field. This phenomenon is studied using the ideas of noncommutative fields theory that examines possible deformations of the canonical structure of some well-known models in (2+1)D$(2+1)\mathrm{D}$. A deformation is constructed linking the massless scalar field theory with the self-dual theory. This is the exact dual of the known deformation connecting the Maxwell theory with the Maxwell–Chern–Simons theory. Duality, radiative corrections, the Julia–Toulouse mechanism and canonical deformations are then used to establish a web of relations between the mentioned theories and to propose a physical picture of the deformation procedure adopted.     

Development and application of electrochemical sensor of boron-doped diamond (BDD) modified by drop casting with tin hexacyanoferrate

Journal of Solid State Electrochemistry - This work presents the development and characterization of an electrochemical sensor of tin hexacyanoferrate (SnHCF), produced from the modification by...