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The FPS1 gene coding for the Fps1p aquaglyceroporin protein of an industrial strain of Saccharomyces cerevisiae was disrupted by inserting CUP1 gene. Wild-type strain, CE25, could only grow on YPD medium containing less than 0.45% (v/v) acetic acid, while recombinant strain T12 with FPS1 disruption could grow on YPD medium with 0.6% (v/v) acetic acid. Under 0.4% (v/v) acetic acid stress (pH 4.26), ethanol production and cell growth rates of T12 were 1.7 ± 0.1 and 0.061 ± 0.003 g/l h, while those of CE25 were 1.2 ± 0.1 and 0.048 ± 0.003 g/l h, respectively. FPS1 gene disruption in an industrial ethanologenic yeast thus increases cell growth and ethanol yield under acetic acid stress, which suggests the potential utility of FPS1 gene disruption for bioethanol production from renewable resources such as lignocelluloses. [ABSTRACT FROM AUTHOR]

Prostate cancer cells expressing prostate-specific membrane antigen (PSMA) have been targeted with RNA aptamer–small interfering (si)RNA chimeras, but therapeutic efficacy in vivo was demonstrated only with intratumoral injection. Clinical translation of this approach will require chimeras that are effective when administered systemically and are amenable to chemical synthesis. To these ends, we enhanced the silencing activity and specificity of aptamer-siRNA chimeras by incorporating modifications that enable more efficient processing of the siRNA by the cellular machinery. These included adding 2-nucleotide 3′-overhangs and optimizing the thermodynamic profile and structure of the duplex to favor processing of the siRNA guide strand. We also truncated the aptamer portion of the chimeras to facilitate large-scale chemical synthesis. The optimized chimeras resulted in pronounced regression of PSMA-expressing tumors in athymic mice after systemic administration. Anti-tumor activity was further enhanced by appending a polyethylene glycol moiety, which increased the chimeras' circulating half-life. [ABSTRACT FROM AUTHOR]

Two new imidazolate-containing complexes, [Ag 5 (Im) 5 ] n (1) and [Ag(2-MeIm)] n (2), were prepared and characterized by X-ray single crystal structure determination. (1) consists of 1-D chains running along three different directions, namely [2 1 1], [2 1 1] and [2 1 1]. This type of packing of chains is unusual. The chains are linked to form a three-dimensional structure through weak Ag···Ag interactions. The silver(I) atom in each chain is linearly coordinated by two nitrogen atoms from different imidazolates and the 1-D chain is somewhat helical due to the geometrical constraints imposed by the 1,3-arrangement of the nitrogen atoms in the imidazolate bridges. (2) is a linear chain in which each silver(I) atom is two-coordinated with the different bridged methylimidazolate nitrogen atoms. The two structures were refined to R 1 =0.0315 for (1) and R 1 =0.0495 for (2). Complexes (1) and (2) are sparingly soluble and very stable in CH 3 CN containing 0.1 mol · L -1 of n - Bu 4 NBF 4 in the range 2.0 to -2.0 V at room temperature and do not undergo any redox process. When being boiled in a solution of 30% sodium hydroxide for two hours, the large colorless prismatic crystals of (1) and (2) remain unchanged. TG/DTG analyses shows that the two complexes begin to decompose at 382 °C for (1) and 357 °C for (2). [ABSTRACT FROM AUTHOR]

Four silver(I) complexes with three pyridyl ligands, 3-amino-pyridine (L 1 ), 2-amino-pyridine (L 2 ), and 4,4'-bipyridine (L 3 ) were synthesized and determined by single-crystal X-ray diffraction. The silver(I) ions in the complexes [Ag(L 1 ) 2 ](CF 3 SO 3 ) (1) and [Ag(L 1 ) 2 ]HCO 3 · 4H 2 O (2) adopt a linear geometry and those in [Ag(L 2 ) 2 (C 6 H 5 COO)] (3) takes a Y -shape. [Ag(L 3 )(CH 3 COOH)] n (NO 3 ) n · 10H 2 O (4) is a polymeric silver(I) complex which consists of four parallel, one-dimensional chains, where there exist two crystallographically different kinds of Ag(I) cations, one is coordinated in a T -shape fashion and the other in a slightly distorted linear geometry. [ABSTRACT FROM AUTHOR]

Hydrogen spillover mechanism of metal-supported covalent-organic frameworks COF-105 is investigated by means of the density functional theory, and the effects of metal catalysts M4 (Pt4, Pd4, and Ni4) on the whole spillover process are systematically analyzed. These three metal catalysts exhibit several similar phenomena: (i) they prefer to deposit on the tetra (4-dihydroxyborylphenyl) silane (TBPS) cluster with surface-contacted configuration; (ii) only the H atoms at the bridge site can migrate to 2,3,6,7,10,11-hexahydroxy triphenylene (HHTP) and TBPS surfaces, and the migration process is an endothermic reaction and not stable; (iii) the introduction of M4 catalyst can greatly reduce the diffusion energy barrier of H atoms, which makes it easier for the H atoms to diffuse on the substrate surface. Differently, all of the H2 molecules spontaneously dissociate into H atoms onto Pt4 and Pd4 clusters. However, the adsorbed H2 molecules on Ni4 cluster show two types of adsorption states: one activated state with stretched H–H bond length of 0.88 Å via the Kubas interaction and five dissociated states with separated hydrogen atoms. Among all the M4 catalysts, the orders of the binding energy of M4 deposited on the substrate and average chemisorption energy per H2 molecule are Pt4>Ni4>Pd4. On the contrary, the orders of the migration and diffusion barriers of H atoms are Pt4

Molecular hydrogen and spiltover hydrogen storages on five two-dimensional (2D) covalent-organic frameworks (COFs) (PPy-COF, TP-COF, BTP-COF, COF-18 Å, and HHTP-DPB COF) are investigated using the grand canonical Monte Carlo (GCMC) simulations and the density functional theory (DFT), respectively. The GCMC simulated results show that HHTP-DPB COF has the best performance for hydrogen storage, followed by BTP-COF, TP-COF, COF-18 Å, and PPy-COF. However, their adsorption amounts at room temperature are all too low to meet the uptake target set by US Department of Energy (US-DOE) and enable practical applications. The effects of pore size, surface area, and isosteric heat of hydrogen on adsorption amount are considered, which indicate that these three factors are all the important factors for determining the H2 adsorption amount. The chemisorptions of spiltover hydrogen atoms on these five COFs represented by the cluster models are investigated using the DFT method. The saturation cluster models are constructed by considering all possible adsorption sites for these cluster models. The average binding energy of a hydrogen atom and the saturation hydrogen storage density are calculated. The large average binding energy indicates that the spillover process may proceed smoothly and reversibly. The saturation hydrogen storage density is much larger than the physisorption uptake of H2 molecules at 298 K and 100 bar (1 bar = 105 Pa), and is close to or exceeds the 2010 US-DOE target of 6 wt% for hydrogen storage. This suggests that the hydrogen storage capacities of these COFs by spillover may be significantly enhanced. Thus 2D COFs studied in this paper are suitable hydrogen storage media by spillover. [ABSTRACT FROM AUTHOR]