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Sample records for c-catalyzed sphingomyelin hydrolysis

  1. Phospholipase C-catalyzed sphingomyelin hydrolysis in a membrane reactor for ceramide production

    DEFF Research Database (Denmark)

    Zhang, Long; Liang, Shanshan; Hellgren, Lars

    2008-01-01

    A membrane reactor for the production of ceramide through sphingomyelin hydrolysis with phospholipase C from Clostridium perfringens was studied for the first time. Ceramide has raised a large interest as an active component in both pharmaceutical and cosmetic industry. The enzymatic hydrolysis...

  2. Immobilization of phospholipase C for the production of ceramide from sphingomyelin hydrolysis

    DEFF Research Database (Denmark)

    Zhang, Long; Hellgren, Lars; Xu, Xuebing

    2007-01-01

    The immobilization of Clostridium perfringens phospholipase C was studied for the first time and the catalytic properties of the immobilized enzyme were investigated for the hydrolysis of sphingomyelin to produce ceramide. Ceramide is of great commercial potentials in cosmetic and pharmaceutical...... industries such as in hair and skin care products, due to its major role in maintaining the water-retaining properties of the epidermis. The feasibility of enzymatic production of ceramide through hydrolysis of sphingomyelin has previously been proven. In order to improve the reusability of the enzyme...

  3. Kinetic study of sphingomyelin hydrolysis for ceramide production

    DEFF Research Database (Denmark)

    Zhang, Long; Hellgren, Lars; Xu, Xuebing

    2008-01-01

    in cosmetic and pharmaceutical industries such as in hair and skin care products. The enzymatic hydrolysis of sphingomyelin has been proved to be a feasible method to produce ceramide. The kinetic performance of sphingomyelin hydrolysis in the optimal two-phase (water:organic solvent) reaction system...

  4. Pathways of sphingomyelin metabolism in cultured fibroblasts from normal and sphingomyelin lipidosis subjects.

    Science.gov (United States)

    Spence, M W; Clarke, J T; Cook, H W

    1983-07-25

    The metabolism of endogenous sphingomyelin labeled with 32P or [methyl-3H]choline and of exogenous [choline-methyl-3H], [32P]-, or [N-acyl-1-14C]sphingomyelin was studied in normal and Niemann-Pick Type A (NP-A) cultured fibroblasts. Despite a greater than 96% decrease in lysosomal sphingomyelinase activity in the NP-A cells, they were able to degrade endogenously produced [32P]- or [methyl-3H]sphingomyelin at normal or near normal rates. Exogenous [methyl-3H]-, [methyl-3H, 32P]-, and [methyl-3H, N-acyl-1-14C] sphingomyelin was taken up intact by normal and NP-A cells, with NP-A cells accumulating 4-8 times more lipid. By 20 h, 50% of the control cell-associated 3H and 32P was recovered in lecithin, and the ratio of activities (3H/32P) indicated most of the phosphorylcholine derived from sphingomyelin had been transferred intact. By comparison in NP-A cells, after a 40-h incubation only 20% of the labeled phosphorylcholine derived from sphingomyelin was recovered in lecithin. With both cell lines, 20 to 50 times more sphingomyelin was hydrolyzed than was taken up by the cells; the reaction products in the medium were ceramide and a mixture of water-soluble compounds such as phosphorylcholine and choline. These results indicate that there are at least two metabolic pathways for sphingomyelin modification in cultured fibroblasts in addition to degradation by the lysosomal acid sphingomyelinase. One route is hydrolysis by a cellular sphingomyelinase. The second is the hydrolysis and/or transfer of phosphorylcholine from sphingomyelin and results in the synthesis of lecithin.

  5. Enzymatic Modification of Sphingomyelin

    DEFF Research Database (Denmark)

    Due to its major role in maintaining the water-retaining properties of the epidermis, ceramide is of great commercial potential in cosmetic and pharmaceuticals such as hair and skin care products. Currently, chemical synthesis of ceramide is a costly process, and developments of alternative cost......-efficient, high yield production methods are of great interest. In the present study, the potential of producing ceramide through the enzymatic hydrolysis of sphingomyelin have been studied. sphingomyelin is a ubiquitous membrane-lipid and rich in dairy products or by-products. It has been verified...... that sphingomyelin modification gives a feasible approach to the potential production of ceramide. The reaction system has been improved through system evaluation and the optimization of several important factors, and phospholipase C from Clostridium perfringens shows higher activity towards the hydrolysis reaction...

  6. Pressure-temperature phase behavior of mixtures of natural sphingomyelin and ceramide extracts.

    Science.gov (United States)

    Barriga, Hanna M G; Parsons, Edward S; McCarthy, Nicola L C; Ces, Oscar; Seddon, John M; Law, Robert V; Brooks, Nicholas J

    2015-03-31

    Ceramides are a group of sphingolipids that act as highly important signaling molecules in a variety of cellular processes including differentiation and apoptosis. The predominant in vivo synthetic pathway for ceramide formation is via sphingomyelinase catalyzed hydrolysis of sphingomyelin. The biochemistry of this essential pathway has been studied in detail; however, there is currently a lack of information on the structural behavior of sphingomyelin- and ceramide-rich model membrane systems, which is essential for developing a bottom-up understanding of ceramide signaling and platform formation. We have studied the lyotropic phase behavior of sphingomyelin-ceramide mixtures in excess water as a function of temperature (30-70 °C) and pressure (1-200 MPa) by small- and wide-angle X-ray scattering. At low ceramide concentrations the mixtures form the ripple gel phase (P(β)') below the gel transition temperature for sphingomyelin, and this observation has been confirmed by atomic force microscopy. Formation of the ripple gel phase can also be induced at higher temperatures via the application of hydrostatic pressure. At high ceramide concentration an inverse hexagonal phase (HII) is formed coexisting with a cubic phase.

  7. Development and industrial application of catalyzer for low-temperature hydrogenation hydrolysis of Claus tail gas

    Directory of Open Access Journals (Sweden)

    Honggang Chang

    2015-10-01

    Full Text Available With the implementation of more strict national environmental protection laws, energy conservation, emission reduction and clean production will present higher requirements for sulfur recovery tail gas processing techniques and catalyzers. As for Claus tail gas, conventional hydrogenation catalyzers are gradually being replaced by low-temperature hydrogenation catalyzers. This paper concentrates on the development of technologies for low-temperature hydrogenation hydrolysis catalyzers, preparation of such catalyzers and their industrial application. In view of the specific features of SO2 hydrogenation and organic sulfur hydrolysis during low-temperature hydrogenation, a new technical process involving joint application of hydrogenation catalyzers and hydrolysis catalyzers was proposed. In addition, low-temperature hydrogenation catalyzers and low-temperature hydrolysis catalyzers suitable for low-temperature conditions were developed. Joint application of these two kinds of catalyzers may reduce the inlet temperatures in the conventional hydrogenation reactors from 280 °C to 220 °C, at the same time, hydrogenation conversion rates of SO2 can be enhanced to over 99%. To further accelerate the hydrolysis rate of organic sulfur, the catalyzers for hydrolysis of low-temperature organic sulfur were developed. In lab tests, the volume ratio of the total sulfur content in tail gas can be as low as 131 × 10−6 when these two kinds of catalyzers were used in a proportion of 5:5 in volumes. Industrial application of these catalyzers was implemented in 17 sulfur recovery tail gas processing facilities of 15 companies. As a result, Sinopec Jinling Petrochemical Company had outstanding application performances with a tail gas discharging rate lower than 77.9 mg/m3 and a total sulfur recovery of 99.97%.

  8. Enzymatic production of ceramide from sphingomyelin

    DEFF Research Database (Denmark)

    Zhang, Long; Hellgren, Lars; Xu, Xuebing

    Ceramide is the key intermediate in the biosynthesis of all complex sphingolipids. Due to its major role in maintaining the water-retaining properties of the epidermis, ceramide is of great commercial potential in cosmetic and pharmaceuticals such as hair and skin care products. Currently, chemical...... contains a ceramide moiety, is a ubiquitous component of animal cell membranes, and dairy products or by-products is a rich source of sphingomyelin. It has been verified that enzymatic modification of sphingomyelin is a feasible approach for production of ceramide. The reaction system has been optimized...... through system evaluation and the optimization of several important factors. Sphingomyelin hydrolysis proved to be more efficient in two-phase (water: organic solvent) system than in one-phase (water-saturated organic solvent) system. Phospholipase C from Clostridium perfringens is the tested enzyme which...

  9. Kinetic study on the acid-catalyzed hydrolysis of cellulose to levulinic acid

    NARCIS (Netherlands)

    Girisuta, B.; Janssen, L. P. B. M.; Heeres, H. J.

    2007-01-01

    A variety of interesting bulk chemicals is accessible by the acid-catalyzed hydrolysis of cellulose. An interesting example is levulinic acid, a versatile precursor for fuel additives, polymers, and resins. A detailed kinetic study on the acid-catalyzed hydrolysis of cellulose to levulinic acid is

  10. Inhibition of endothelial lipase activity by sphingomyelin in the lipoproteins.

    Science.gov (United States)

    Yang, Peng; Belikova, Natalia A; Billheimer, Jeff; Rader, Daniel J; Hill, John S; Subbaiah, Papasani V

    2014-10-01

    Endothelial lipase (EL) is a major determinant of plasma HDL concentration, its activity being inversely proportional to HDL levels. Although it is known that it preferentially acts on HDL compared to LDL and VLDL, the basis for this specificity is not known. Here we tested the hypothesis that sphingomyelin, a major phospholipid in lipoproteins is a physiological inhibitor of EL, and that the preference of the enzyme for HDL may be due to low sphingomyelin/phosphatidylcholine (PtdCho) ratio in HDL, compared to other lipoproteins. Using recombinant human EL, we showed that sphingomyelin inhibits the hydrolysis of PtdCho in the liposomes in a concentration-dependent manner. While the enzyme showed lower hydrolysis of LDL PtdCho, compared to HDL PtdCho, this difference disappeared after the degradation of lipoprotein sphingomyelin by bacterial sphingomyelinase. Analysis of molecular species of PtdCho hydrolyzed by EL in the lipoproteins showed that the enzyme preferentially hydrolyzed PtdCho containing polyunsaturated fatty acids (PUFA) such as 22:6, 20:5, 20:4 at the sn-2 position, generating the corresponding PUFA-lyso PtdCho. This specificity for PUFA-PtdCho species was not observed after depletion of sphingomyelin by sphingomyelinase. These results show that sphingomyelin not only plays a role in regulating EL activity, but also influences its specificity towards PtdCho species.

  11. Kinetics of catalyzed hydrolysis of 4-methylumbelliferyl caprylate (MUCAP) salmonella reagent

    Science.gov (United States)

    Al-Kady, Ahmed S.; Ahmed, El-Sadat I.; Gaber, M.; Hussein, Mohamed M.; Ebeid, El-Zeiny M.

    2011-09-01

    The kinetics of chemical hydrolysis including neutral, acid- and base-catalyzed hydrolysis of 4-methylumbelliferyl caprylate (MUCAP) salmonella reagent were studied at different temperatures. The rate constants and activation parameters were determined by following the build-up of fluorescence peak of the hydrolysis product 4-methylumbelliferone (4-MU). The time scale of esterase enzyme hydrolysis caused by salmonella was compared with chemical hydrolysis as a background process.

  12. Secondary deuterium isotope effects for acid-catalyzed hydrolysis of inosine and adenosine

    International Nuclear Information System (INIS)

    Romero, R.; Stein, R.; Bull, H.G.; Cordes, E.H.

    1978-01-01

    Kinetic α deuterium isotope effects have been measured for acid-catalyzed hydrolysis of inosine and adenosine. For inosine hydrolysis, values of k/sub H/k/sub D/ follow: in 1.0 M HCl, 1.21 and 1.20 at 25 and 50 0 C, respectively; in 0.1 M HCl, 1.19 and 1.18 at 25 and 50 0 C, respectively. For adenosine hydrolysis, k/sub H/k/sub D/ is 1.23 in 0.1 M HCl at 25 0 C. The values require that the transition states for hydrolysis of both the monocation and dication of inosine and the dication of adenosine have marked oxocarbonium ion character. Detailed mechanisms which accord with this and other experimental observations include (1) a classical Al mechanism in which the C--N bond is largely cleaved in the transition state; (2) a mechanism involving some form of nucleophilic participation by solvent in which bond cleavage is advanced relative to bond formation in the transition state; or (3) complete C--N bond cleavage with rate-determining diffusion apart of oxocarbonium ion and purine base. 53 references, 1 figure, 2 tables

  13. Lactam hydrolysis catalyzed by mononuclear metallo-ß-bactamases

    DEFF Research Database (Denmark)

    Olsen, Lars; Antony, J; Ryde, U

    2003-01-01

    Two central steps in the hydrolysis of lactam antibiotics catalyzed by mononuclear metallo-beta-lactamases, formation of the tetrahedral intermediate and its breakdown by proton transfer, are studied for model systems using the density functional B3LYP method. Metallo-beta-lactamases have two metal...

  14. Optimization of Two-Step Acid-Catalyzed Hydrolysis of Oil Palm Empty Fruit Bunch for High Sugar Concentration in Hydrolysate

    Directory of Open Access Journals (Sweden)

    Dongxu Zhang

    2014-01-01

    Full Text Available Getting high sugar concentrations in lignocellulosic biomass hydrolysate with reasonable yields of sugars is commercially attractive but very challenging. Two-step acid-catalyzed hydrolysis of oil palm empty fruit bunch (EFB was conducted to get high sugar concentrations in the hydrolysate. The biphasic kinetic model was used to guide the optimization of the first step dilute acid-catalyzed hydrolysis of EFB. A total sugar concentration of 83.0 g/L with a xylose concentration of 69.5 g/L and a xylose yield of 84.0% was experimentally achieved, which is in well agreement with the model predictions under optimal conditions (3% H2SO4 and 1.2% H3PO4, w/v, liquid to solid ratio 3 mL/g, 130°C, and 36 min. To further increase total sugar and xylose concentrations in hydrolysate, a second step hydrolysis was performed by adding fresh EFB to the hydrolysate at 130°C for 30 min, giving a total sugar concentration of 114.4 g/L with a xylose concentration of 93.5 g/L and a xylose yield of 56.5%. To the best of our knowledge, the total sugar and xylose concentrations are the highest among those ever reported for acid-catalyzed hydrolysis of lignocellulose.

  15. Hydrolysis of cellulose catalyzed by quaternary ammonium perrhenates in 1-allyl-3-methylimidazolium chloride.

    Science.gov (United States)

    Wang, Jingyun; Zhou, Mingdong; Yuan, Yuguo; Zhang, Quan; Fang, Xiangchen; Zang, Shuliang

    2015-12-01

    Quaternary ammonium perrhenates were applied as catalyst to promote the hydrolysis of cellulose in 1-allyl-3-methylimidazolium chloride ([Amim]Cl). The quaternary ammonium perrhenates displayed good catalytic performance for cellulose hydrolysis. Water was also proven to be effective to promote cellulose hydrolysis. Accordingly, 97% of total reduced sugar (TRS) and 42% of glucose yields could be obtained under the condition of using 5mol% of tetramethyl ammonium perrhenate as catalyst, 70μL of water, ca. 0.6mmol of microcrystalline cellulose (MCC) and 2.0g of [Amim]Cl as solvent under microwave irradiation for 30min at 150°C (optimal conditions). The influence of quaternary ammonium cation on the efficiency of cellulose hydrolysis was examined based on different cation structures of perrhenates. The mechanism on perrhenate catalyzed cellulose hydrolysis is also discussed, whereas hydrogen bonding between ReO4 anion and hydroxyl groups of cellulose is assumed to be the key step for depolymerization of cellulose. Copyright © 2015. Published by Elsevier Ltd.

  16. On the Brønsted acid-catalyzed homogeneous hydrolysis of furans.

    Science.gov (United States)

    Nikbin, Nima; Caratzoulas, Stavros; Vlachos, Dionisios G

    2013-11-01

    Furan affairs: Electronic structure calculations of the homogeneous Brønsted acid-catalyzed hydrolysis of 2,5-dimethylfuran show that proton transfer to the β-position is rate-limiting and provides support that the hydrolysis follows general acid catalysis. By means of projected Fukui indices, we show this to be the case for unsubstituted, 2-, and 2,5-substituted furans with electron-donating groups. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Hydrogen-bonded intermediates and transition states during spontaneous and acid-catalyzed hydrolysis of the carcinogen (+)-anti-BPDE.

    Science.gov (United States)

    Palenik, Mark C; Rodriguez, Jorge H

    2014-07-07

    Understanding mechanisms of (+)-anti-BPDE detoxification is crucial for combating its mutagenic and potent carcinogenic action. However, energetic-structural correlations of reaction intermediates and transition states during detoxification via hydrolysis are poorly understood. To gain mechanistic insight we have computationally characterized intermediate and transition species associated with spontaneous and general-acid catalyzed hydrolysis of (+)-anti-BPDE. We studied the role of cacodylic acid as a proton donor in the rate limiting step. The computed activation energy (ΔG‡) is in agreement with the experimental value for hydrolysis in a sodium cacodylate buffer. Both types of, spontaneous and acid catalyzed, BPDE hydrolysis can proceed through low-entropy hydrogen bonded intermediates prior to formation of transition states whose energies determine reaction activation barriers and rates.

  18. Solid Acid-Catalyzed Cellulose Hydrolysis Monitored by In Situ ATR-IR Spectroscopy

    NARCIS (Netherlands)

    Zakzeski, J.; Grisel, R.J.H.; Smit, A.T.; Weckhuysen, B.M.

    2012-01-01

    The solid acid-catalyzed hydrolysis of cellulose was studied under elevated temperatures and autogenous pressures using in situ ATR-IR spectroscopy. Standards of cellulose and pure reaction products, which include glucose, fructose, hydroxymethylfurfural (HMF), levulinic acid (LA), formic acid, and

  19. Lactam hydrolysis catalyzed by mononuclear metallo-beta-lactamases: A density functional study

    DEFF Research Database (Denmark)

    Hemmingsen, Lars Bo Stegeager; Olsen, L.; Antony, J.

    2003-01-01

    Two central steps in the hydrolysis of lactam antibiotics catalyzed by mononuclear metallo-beta-lactamases, formation of the tetrahedral intermediate and its breakdown by proton transfer, are studied for model systems using the density functional B3LYP method. Metallo-beta-lactamases have two metal...

  20. Behaviors of glucose decomposition during acid-catalyzed hydrothermal hydrolysis of pretreated Gelidium amansii.

    Science.gov (United States)

    Jeong, Tae Su; Choi, Chang Ho; Lee, Ji Ye; Oh, Kyeong Keun

    2012-07-01

    Acid-catalyzed hydrothermal hydrolysis is one path to cellulosic glucose and subsequently to its dehydration end products such as hydroxymethyl furfural (HMF), formic acid and levulinic acid. The effect of sugar decomposition not only lowers the yield of fermentable sugars but also forms decomposition products that inhibit subsequent fermentation. The present experiments were conducted with four different acid catalysts (H(2)SO(4), HNO(3), HCl, and H(3)PO(4)) at various acid normalities (0.5-2.1N) in batch reactors at 180-210 °C. From the results, H(2)SO(4) was the most suitable catalyst for glucose production, but glucose decomposition occurred during the hydrolysis. The glucose production was maximized at 160.7 °C, 2.0% (w/v) H(2)SO(4), and 40 min, but resulted in a low glucan yield of 33.05% due to the decomposition reactions, which generated formic acid and levulinic acid. The highest concentration of levulinic acid, 7.82 g/L, was obtained at 181.2 °C, 2.0% (w/v) H(2)SO(4), and 40 min. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Mechanism and activation for allosteric adenosine 5'-monophosphate nucleosidase. Kinetic alpha-deuterium isotope effects for the enzyme-catalyzed hydrolysis of adenosine 5'-monophosphate and nicotinamide mononucleotide

    International Nuclear Information System (INIS)

    Skoog, M.T.

    1986-01-01

    The kinetic alpha-deuterium isotope effect on Vmax/Km for hydrolysis of NMN catalyzed by AMP nucleosidase at saturating concentrations of the allosteric activator MgATP2- is kH/kD = 1.155 +/- 0.012. This value is close to that reported previously for the nonenzymatic hydrolysis of nucleosides of related structure, suggesting that the full intrinsic isotope effect for enzymatic NMN hydrolysis is expressed under these conditions; that is, bond-changing reactions are largely or completely rate-determining and the transition state has marked oxocarbonium ion character. The kinetic alpha-deuterium isotope effect for this reaction is unchanged when deuterium oxide replaces water as solvent, corroborating this conclusion. Furthermore, this isotope effect is independent of pH over the range 6.95-9.25, for which values of Vmax/Km change by a factor of 90, suggesting that the isotope-sensitive and pH-sensitive steps for AMP-nucleosidase-catalyzed NMN hydrolysis are the same. Values of kH/kD for AMP nucleosidase-catalyzed hydrolysis of NMN decrease with decreasing saturation of enzyme with MgATP2- and reach unity when the enzyme is less than half-saturated with this activator. This requires that the rate-determining step changes from cleavage of the covalent C-N bond to one which is isotope-independent. In contrast to the case for NMN hydrolysis, AMP nucleosidase-catalyzed hydrolysis of AMP at saturating concentrations of MgATP2- shows a kinetic alpha-deuterium isotope effect of unity. Thus, covalent bond-changing reactions are largely or completely rate-determining for hydrolysis of a poor substrate, NMN, but make little or no contribution to rate-determining step for hydrolysis of a good substrate, AMP, by maximally activated enzyme. This behavior has several precedents

  2. β-Secondary and solvent deuterium kinetic isotope effects and the mechanisms of base- and acid-catalyzed hydrolysis of penicillanic acid

    International Nuclear Information System (INIS)

    Deraniyagala, S.A.; Adediran, S.A.; Pratt, R.F.

    1995-01-01

    β-Secondary and solvent deuterium kinetic isotope effects have been determined at 25 degrees C for the alkaline and acid-catalyzed hydrolysis of penicillanic acid. In order to determine the former isotope effect, [6,6- 2 H 2 ]dideuteriopenicillanic acid has been synthesized. In alkaline solution, the former isotope effect was found to be 0.95 ± 0.01. These values support the B AC 2 mechanism of hydrolysis with rate-determining formation of the tetrahedral intermediate that has been proposed for other β-lactams. The measured β-secondary kinetic isotope for the acid-catalyzed reaction was 1.00 ± 0.01. The data indicates that a likely pathway of acid-catalyzed hydrolysis would be that of an A AC 1 mechanism with an intermediate acylium ion. If this were so, the calculated β-secondary isotope effect per hydrogen coplanar with the breaking C-N bond and corrected for the inductive effect of deuterium would be 1.06 ± 0.01. This suggests an early A AC 1 transition state, which would be reasonable in this case because of destabilization of the N-protonated amide with respect to the acylium ion because of ring strain. The absence of specific participation by solvent in the transition state, as would be expected of an A AC 1 but not an associative mechanism, is supported by the strongly inverse solvent deuterium kinetic isotope effect of 0.25 ± 0.00 in 1 M HCl and 0.22 ± 0.01 in 33.3 wt % H 2 SO 4 . 1 fig., 3 tabs

  3. Modeling evolution of hydrogen bonding and stabilization of transition states in the process of cocaine hydrolysis catalyzed by human butyrylcholinesterase.

    Science.gov (United States)

    Gao, Daquan; Zhan, Chang-Guo

    2006-01-01

    Molecular dynamics (MD) simulations and quantum mechanical/molecular mechanical (QM/MM) calculations were performed on the prereactive enzyme-substrate complex, transition states, intermediates, and product involved in the process of human butyrylcholinesterase (BChE)-catalyzed hydrolysis of (-)-cocaine. The computational results consistently reveal a unique role of the oxyanion hole (consisting of G116, G117, and A199) in BChE-catalyzed hydrolysis of cocaine, compared to acetylcholinesterase (AChE)-catalyzed hydrolysis of acetylcholine. During BChE-catalyzed hydrolysis of cocaine, only G117 has a hydrogen bond with the carbonyl oxygen (O31) of the cocaine benzoyl ester in the prereactive BChE-cocaine complex, and the NH groups of G117 and A199 are hydrogen-bonded with O31 of cocaine in all of the transition states and intermediates. Surprisingly, the NH hydrogen of G116 forms an unexpected hydrogen bond with the carboxyl group of E197 side chain and, therefore, is not available to form a hydrogen bond with O31 of cocaine in the acylation. The NH hydrogen of G116 is only partially available to form a weak hydrogen bond with O31 of cocaine in some structures involved in the deacylation. The change of the estimated hydrogen-bonding energy between the oxyanion hole and O31 of cocaine during the reaction process demonstrates how the protein environment can affect the energy barrier for each step of the BChE-catalyzed hydrolysis of cocaine. These insights concerning the effects of the oxyanion hole on the energy barriers provide valuable clues on how to rationally design BChE mutants with a higher catalytic activity for the hydrolysis of (-)-cocaine. 2005 Wiley-Liss, Inc.

  4. Modeling Evolution of Hydrogen Bonding and Stabilization of Transition States in the Process of Cocaine Hydrolysis Catalyzed by Human Butyrylcholinesterase

    OpenAIRE

    Gao, Daquan; Zhan, Chang-Guo

    2006-01-01

    Molecular dynamics (MD) simulations and quantum mechanical/molecular mechanical (QM/MM) calculations were performed on the prereactive enzyme-substrate complex, transition states, intermediates, and product involved in the process of human butyrylcholinesterase (BChE)-catalyzed hydrolysis of (−)-cocaine. The computational results consistently reveal a unique role of the oxyanion hole (consisting of G116, G117, and A199) in BChE-catalyzed hydrolysis of cocaine, as compared to acetylcholinester...

  5. Hydrolysis of Methylal Catalyzed by Ion Exchange Resins in Aqueous Media

    Science.gov (United States)

    He, Gaoyin; Dai, Fangfang; Shi, Midong; Li, Qingsong; Yu, Yingmin

    2018-05-01

    In the present work, the chemical equilibrium and kinetics of methylal (PODE1) hydrolysis catalyzed by ion-exchange resin in aqueous solutions were investigated. The study covers temperatures between 333.15 and 363.15 K at various starting compositions covering (PODE1 + MeOH)/water molar ratio ranges from 0.5 to 1.5 in a time scale. On the basis of the experimental results, a mole fraction-based model of the chemical equilibrium and a pseudohomogeneous model are proposed to fit data based on true amount of monomeric formaldehyde. It has been demonstrated that the hydrolysis of PODE1 is slightly endothermic with the enthalpy 8.19 kJ/mol and the rate determining step. Finally, a feed-forward artificial neural networks (ANN) model is developed to model the concentration change of methanol in aqueous solutions. The results showed that the predicted data from designed ANN model were in good agreement with the experimental data with the coefficient ( R 2) of 0.98. Designed ANN provides a reliable method for modeling the hydrolysis reaction of methylal (PODE1).

  6. FeCl3-catalyzed ethanol pretreatment of sugarcane bagasse boosts sugar yields with low enzyme loadings and short hydrolysis time.

    Science.gov (United States)

    Zhang, Hongdan; Zhang, Shuaishuai; Yuan, Hongyou; Lyu, Gaojin; Xie, Jun

    2018-02-01

    An organosolv pretreatment system consisting of 60% ethanol and 0.025 mol·L -1 FeCl 3 under various temperatures was developed in this study. During the pretreatment, the highest xylose yield was 11.4 g/100 g raw material, representing 49.8% of xylose in sugarcane bagasse. Structural features of raw material and pretreated substrates were characterized to better understand how hemicellulose removal and delignification affected subsequent enzymatic hydrolysis. The 160 °C pretreated solid presented a remarkable glucose yield of 93.8% for 72 h. Furthermore, the influence of different additives on the enzymatic hydrolysis of pretreated solid was investigated. The results indicated that the addition of Tween 80 shortened hydrolysis time to 6 h and allowed a 50% reduction of enzyme loading to achieve the same level of glucose yield. This work suggested that FeCl 3 -catalyzed organosolv pretreatment could improve the enzymatic hydrolysis significantly and reduce the hydrolysis time and enzyme dosage with the addition of Tween 80. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Kinetics and stereochemistry of hydrolysis of an N-(phenylacetyl)-α-hydroxyglycine ester catalyzed by serine β-lactamases and DD-peptidases.

    Science.gov (United States)

    Pelto, Ryan B; Pratt, R F

    2012-09-28

    The α-hydroxydepsipeptide 3-carboxyphenyl N-(phenylacetyl)-α-hydroxyglycinate (5) is a quite effective substrate of serine β-lactamases and low molecular mass DD-peptidases. The class C P99 and ampC β-lactamases catalyze the hydrolysis of both enantiomers of 5, although they show a strong preference for one of them. The class A TEM-2 and class D OXA-1 β-lactamases and the Streptomyces R61 and Actinomadura R39 DD-peptidases catalyze hydrolysis of only one enantiomer of at any significant rate. Experiments show that all of the above enzymes strongly prefer the same enantiomer, a surprising result since β-lactamases usually prefer L(S) enantiomers and DD-peptidases D(R). Product analysis, employing peptidylglycine α-amidating lyase, showed that the preferred enantiomer is D(R). Thus, it is the β-lactamases that have switched preference rather than the DD-peptidases. Molecular modeling of the P99 β-lactamase active site suggests that the α-hydroxyl 5 of may interact with conserved Asn and Lys residues. Both α-hydroxy and α-amido substituents on a glycine ester substrate can therefore enhance its productive interaction with the β-lactamase active site, although their effects are not additive; this may also be true for inhibitors.

  8. Rubber muscle actuation with pressurized CO2 from enzyme-catalyzed urea hydrolysis

    Science.gov (United States)

    Sutter, Thomas M.; Dickerson, Matthew B.; Creasy, Terry S.; Justice, Ryan S.

    2013-09-01

    A biologically inspired pneumatic pressure source was designed and sized to supply high pressure CO2(g) to power a rubber muscle actuator. The enzyme urease served to catalyze the hydrolysis of urea, producing CO2(g) that flowed into the actuator. The actuator’s power envelope was quantified by testing actuator response on a custom-built linear-motion rig. Reaction kinetics and available work density were determined by replacing the actuator with a double-action piston and measuring volumetric gas generation against a fixed pressure on the opposing piston. Under the conditions investigated, urease catalyzed the generation of up to 0.81 MPa (117 psi) of CO2(g) in the reactor headspace within 18 min, and the evolved gas produced a maximum work density of 0.65 J ml-1.

  9. Rubber muscle actuation with pressurized CO2 from enzyme-catalyzed urea hydrolysis

    International Nuclear Information System (INIS)

    Sutter, Thomas M; Dickerson, Matthew B; Creasy, Terry S; Justice, Ryan S

    2013-01-01

    A biologically inspired pneumatic pressure source was designed and sized to supply high pressure CO 2(g) to power a rubber muscle actuator. The enzyme urease served to catalyze the hydrolysis of urea, producing CO 2(g) that flowed into the actuator. The actuator’s power envelope was quantified by testing actuator response on a custom-built linear-motion rig. Reaction kinetics and available work density were determined by replacing the actuator with a double-action piston and measuring volumetric gas generation against a fixed pressure on the opposing piston. Under the conditions investigated, urease catalyzed the generation of up to 0.81 MPa (117 psi) of CO 2(g) in the reactor headspace within 18 min, and the evolved gas produced a maximum work density of 0.65 J ml −1 . (paper)

  10. Understanding the hydrolysis mechanism of ethyl acetate catalyzed by an aqueous molybdocene: a computational chemistry investigation.

    Science.gov (United States)

    Tílvez, Elkin; Cárdenas-Jirón, Gloria I; Menéndez, María I; López, Ramón

    2015-02-16

    A thoroughly mechanistic investigation on the [Cp2Mo(OH)(OH2)](+)-catalyzed hydrolysis of ethyl acetate has been performed using density functional theory methodology together with continuum and discrete-continuum solvation models. The use of explicit water molecules in the PCM-B3LYP/aug-cc-pVTZ (aug-cc-pVTZ-PP for Mo)//PCM-B3LYP/aug-cc-pVDZ (aug-cc-pVDZ-PP for Mo) computations is crucial to show that the intramolecular hydroxo ligand attack is the preferred mechanism in agreement with experimental suggestions. Besides, the most stable intermediate located along this mechanism is analogous to that experimentally reported for the norbornenyl acetate hydrolysis catalyzed by molybdocenes. The three most relevant steps are the formation and cleavage of the tetrahedral intermediate immediately formed after the hydroxo ligand attack and the acetic acid formation, with the second one being the rate-determining step with a Gibbs energy barrier of 36.7 kcal/mol. Among several functionals checked, B3LYP-D3 and M06 give the best agreement with experiment as the rate-determining Gibbs energy barrier obtained only differs 0.2 and 0.7 kcal/mol, respectively, from that derived from the experimental kinetic constant measured at 296.15 K. In both cases, the acetic acid elimination becomes now the rate-determining step of the overall process as it is 0.4 kcal/mol less stable than the tetrahedral intermediate cleavage. Apart from clarifying the identity of the cyclic intermediate and discarding the tetrahedral intermediate formation as the rate-determining step for the mechanism of the acetyl acetate hydrolysis catalyzed by molybdocenes, the small difference in the Gibbs energy barrier found between the acetic acid formation and the tetrahedral intermediate cleavage also uncovers that the rate-determining step could change when studying the reactivity of carboxylic esters other than ethyl acetate substrate specific toward molybdocenes or other transition metal complexes. Therefore

  11. Influence of lecithin liposomes on chlorophyllase-catalyzed chlorophyll hydrolysis. Comparison of intramembraneous and solubilized Phaeodactylum chlorophyllase

    NARCIS (Netherlands)

    Terpstra, Willemke

    1980-01-01

    1. 1. Chlorophyllase-catalyzed chlorophyll hydrolysis is greatly enhanced by the addition of divalent cations (Mg2+) combined with a reducing agent (dithiothreitol, ascorbate). A similar effect is obtained by the addition of lecithin. In the presence of lecithin, dithiothreitol has only slight or no

  12. [PREPARATION OF HUMAN TISSUE PROTEIN EXTRACTS ENRICHED WITH THE SPHINGOMYELIN SYNTHASE 1].

    Science.gov (United States)

    Sudarkina, O Yu; Dergunova, L V

    2015-01-01

    Sphingomyelin synthase 1 (SMS 1) catalyzes sphingomyelin biosynthesis in eukaryotic cells. We previously studied the structure of the human SGMS1 gene, which encodes the enzyme and its numerous transcripts. The tissue-specific expression of the transcripts was also described. Analysis of the SMS1 protein expression in human tissues using immunoblotting of tissue extracts prepared in the RIPA (Radio Immuno-Precipitation Assay) buffer revealed a weak signal in renal cortex, testis, lung, and no signal in placenta and lymphatic node. In this work, a new method of preparation of the tissue protein extracts enriched with SMS1 was suggested. The method based on the consecutive extraction with a buffer containing 0.05 and 1 mg/ml of the Quillaja saponaria saponin allowed SMS1 to be detected in all tissues tested. The SMS1 content in the saponin extract of kidney cortex is about 12-fold higher compared to the RIPA extraction procedure.

  13. Hydrolyses of 2- and 4-fluoro N-heterocycles. 3. Nucleophilic catalysis by buffer bases in the general acid catalyzed hydrolysis of 4-fluoroquinaldine

    International Nuclear Information System (INIS)

    Muscio, O.J. Jr.; Theobald, P.G.; Rutherford, D.R.

    1989-01-01

    Pseudo-first-order rate constants and catalytic rate constants are reported for the buffer-catalyzed hydrolysis of 4-fluoroquinaldine (1) in carboxylic acid and phosphoric acid buffers. The buffer catalysis is consistent with specific acid, general base catalysis. Hydrolyses in 99% 18 O-labeled acetate, indicate that the predominant catalytic mode for the acetic acid/acetate buffer system is nucleophilic catalysis by the acetate anion coupled with specific acid catalysis. The other buffers presumably react in a similar manner. A Broensted-type plot of the catalytic rate constants for hydrolysis of protonated 1 has a slope of 0.57, with formate deviating positively from the line determined by acetate, chloroacetate, monohydrogen phosphate, and water. This Broensted slope is less than that found for hydrolysis of the 2-fluoro-1-methylpyridinium ion, 2, but is still within the range expected for aromatic nucleophilic substitution. Rate constants and 18 O-labeling results for hydrolysis in acetate buffer are also reported for 4-acetoxyquinaldine (3), the proposed intermediate in the acetate-catalyzed hydrolysis of 1. 15 references, 5 figures, 3 tables

  14. 2-Acetylthiamin pyrophosphate (acetyl-TPP) pH-rate profile for hydrolysis of acetyl-TPP and isolation of acetyl-TPP as a transient species in pyruvate dehydrogenase catalyzed reactions

    International Nuclear Information System (INIS)

    Gruys, K.J.; Datta, A.; Frey, P.A.

    1989-01-01

    Rate constants for the hydrolysis of acetyl-TPP were measured pH values of 2.5 and 7.5 and plotted as log k obs versus pH. The pH-rate profile defined two legs, each with a slope of +1 but separated by a region of decreased slope between pH 4 and pH 6. The rates were insensitive to buffer concentrations. Each leg of the profile reflected specific-base-catalyzed hydrolysis of acetyl-TPP, analogous to the hydrolysis of 2-acetyl-3,4-dimethylthiazolium ion. The separation of the two legs of this profile has been shown to be caused by the ionization of a group exhibiting a pK a of 4.73 within acetyl-TPP that is remote from the acetyl group, the aminopyrimidine ring, which is promoted below pH 4.73. The protonation level of this ring has been shown to control the equilibrium partitioning of acetyl-TPP among its carbinolamine, keto, and hydrate forms. The differential partitioning of these species is a major factor causing the separation between the two legs of the pH-rate profile. The characteristic pH-rate profile and the availability of synthetic acetyl-TPP have facilitated the isolation and identification of [1- 14 C]acetyl-TPP from acid-quenched enymatic reaction mixtures at steady states. [1- 14 C]Acetyl-TPP was identified as a transient species in reactions catalyzed by the PDH complex or the pyruvate dehydrogenase component of the complex (E 1 ). The pH-rate profile for hydrolysis of [1- 14 C]-acetyl-TPP, isolated from enzymatic reactions was found to be indistinguishable from that for authentic acetyl-TPP, which constituted positive identification of the 14 C-labeled enzymic species

  15. The trypsin-catalyzed hydrolysis of monomolecular films of lysylphosphatidylglycerol

    NARCIS (Netherlands)

    Gould, R.M.; Dawson, R.M.C.

    1972-01-01

    The hydrolysis by trypsin of the bacterial phospholipid, lysylphosphatidyl-glycerol has been studied at the air-water interface. High specific activity [14C]-lysylphosphatidylglycerol was prepared biosynthetically and the trypsin action followed by measuring the loss of surface radioactivity from a

  16. The GDP-switched GAF domain of DcpA modulates the concerted synthesis/hydrolysis of c-di-GMP in Mycobacterium smegmatis.

    Science.gov (United States)

    Chen, Hui-Jie; Li, Na; Luo, Ye; Jiang, Yong-Liang; Zhou, Cong-Zhao; Chen, Yuxing; Li, Qiong

    2018-04-09

    The second messenger c-di-GMP [bis-(3'-5')-cyclic dimeric guanosine monophosphate] plays a key role in bacterial growth, survival and pathogenesis, and thus its intracellular homeostasis should be finely maintained. Mycobacterium smegmatis encodes a GAF (mammalian c G MP-regulated phosphodiesterases, Anabaena a denylyl cyclases and Escherichia coli transcription activator F hlA) domain containing bifunctional enzyme DcpA ( d iguanylate c yclase and p hosphodiesterase A ) that catalyzes the synthesis and hydrolysis of c-di-GMP . Here, we found that M. smegmatis DcpA catalyzes the hydrolysis of c-di-GMP at a higher velocity, compared with synthetic activity, resulting in a sum reaction from the ultimate substrate GTP to the final product pGpG [5'-phosphoguanylyl-(3'-5')-guanosine]. Fusion with the N-terminal GAF domain enables the GGDEF (Gly-Gly-Asp-Glu-Phe) domain of DcpA to dimerize and accordingly gain synthetic activity. Screening of putative metabolites revealed that GDP is the ligand of the GAF domain. Binding of GDP to the GAF domain down-regulates synthetic activity, but up-regulates hydrolytic activity, which, in consequence, might enable a timely response to the transient accumulation of c-di-GMP at the stationary phase or under stresses. Combined with the crystal structure of the EAL (Glu-Ala-Leu) domain and the small-angle X-ray scattering data, we propose a putative regulatory model of the GAF domain finely tuned by the intracellular GTP/GDP ratio. These findings help us to better understand the concerted control of the synthesis and hydrolysis of c-di-GMP in M. smegmatis in various microenvironments. © 2018 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  17. Size exclusion chromatography for the quantitative profiling of the enzyme-catalyzed hydrolysis of xylo-oligosaccharides

    DEFF Research Database (Denmark)

    Rasmussen, Louise Enggaard; Meyer, Anne S.

    2010-01-01

    High-performance size exclusion chromatography (HPSEC) is a widely used method for the qualitative profiling of oligosaccharide mixtures, including, for example, enzymatic hydrolysates of plant biomass materials. A novel method employing HPSEC for the quantitative analytical profiling......, the method was designed using 0.1 M CH3COONa both in the mobile phase and as the sample solution matrix, after systematic evaluation of the influence of the mobile phase, including the type, ionic strength, and pH, on the refractive index detector response. A time study of the enzyme-catalyzed hydrolysis...

  18. Saliva-catalyzed hydrolysis of a ketobemidone ester prodrug

    DEFF Research Database (Denmark)

    Hansen, L.B.; Christrup, Lona Louring; Bundgaard, H.

    1992-01-01

    Saliva enzyme-catalysed hydrolysis of ester prodrugs or drugs containing sensitive ester groups may be a limiting factor for the buccal absorption of such compounds. Using the isopropyl carbonate ester of ketobemidone as a model substance of a hydrolysis-sensitive prodrug the esterase activity...... of human saliva has been characterized as a function of various factors. The esterase activity was found to decrease rapidly upon storage of the saliva at 37°C. The activity increased with increasing pH in the range 4.5-7.4 and with increasing salivation flow rate up to a rate of 0.9 ml min. Under resting...... conditions, the flow rate was about 0.2 ml min which implied a greatly decreased esterase activity. The activity was highest after fasting and decreased after intake of a meal. The intraindividual variation in the saliva esterase activity was small whereas a larger interindividual variation was found....

  19. Aquivion Perfluorosulfonic Superacid as an Efficient Pickering Interfacial Catalyst for the Hydrolysis of Triglycerides.

    Science.gov (United States)

    Shi, Hui; Fan, Zhaoyu; Hong, Bing; Pera-Titus, Marc

    2017-09-11

    Rational design of the surface properties of heterogeneous catalysts can boost the interfacial activity in biphasic reactions through the generation of Pickering emulsions. This concept, termed Pickering interfacial catalysis (PIC), has shown promising credentials in acid-catalyzed transesterification, ester hydrolysis, acetalization, etherification, and alkylation reactions. PIC has now been applied to the efficient, solvent-free hydrolysis of the triglyceride glyceryl trilaurate to lauric acid, catalyzed by Aquivion perfluorosulfonic superacid at mild conditions (100 °C and ambient pressure). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Application of acid-catalyzed hydrolysis of dispersed organic solvent in developing new microencapsulation process technology.

    Science.gov (United States)

    Lee, Honghwa; Lee, Sunhwa; Bhattacharjee, Himanshu; Sah, Hongkee

    2012-01-01

    The aim of this study was to evaluate a new microencapsulation technology employing an acid-catalyzed solvent extraction method in conjunction to an emulsion-based microencapsulation process. Its process consisted of emulsifying a dispersed phase of poly(D,L-lactide-co-glycolide) and isopropyl formate in an aqueous phase. This step was followed by adding hydrochloric acid to the resulting oil-in-water emulsion, in order to initiate the hydrolysis of isopropyl formate dissolved in the aqueous phase. Its hydrolysis caused the liberation of water-soluble species, that is, isopropanol and formic acid. This event triggered continual solvent leaching out of emulsion droplets, thereby initiating microsphere solidification. This new processing worked well for encapsulation of progesterone and ketoprofen that were chosen as a nonionizable model drug and a weakly acidic one, respectively. Furthermore, the structural integrity of poly(D,L-lactide-co-glycolide) was retained during microencapsulation. The new microencapsulation technology, being conceptually different from previous approaches, might be useful in preparing various polymeric particles.

  1. Automated enzymatic measurement of lecithin, sphingomyelin, and phosphatidylglycerol in amniotic fluid.

    Science.gov (United States)

    Bradley, C A; Salhany, K E; Entman, S S; Aleshire, S L; Parl, F F

    1987-01-01

    We describe methods for automated enzymatic measurement of lecithin, sphingomyelin, and phosphatidylglycerol in amniotic fluid. Phospholipase C (EC 3.1.4.3) and sphingomyelin phosphodiesterase (EC 3.1.4.12) are reacted with lecithin and sphingomyelin, respectively, to liberate phosphocholine. Phosphocholine is then reacted with alkaline phosphatase, choline oxidase, peroxidase, and 4-aminoantipyrine to form a colored complex, for which the absorbance at 500 nm is measured with a centrifugal analyzer. Phosphatidylglycerol is hydrolyzed by phospholipase D (EC 3.1.4.4) to form glycerol, which is subsequently reacted with ATP and NAD+ in the presence of glycerol kinase and glycerol-3-phosphate dehydrogenase to yield NADH. The absorbance of the NADH formed is measured at 340 nm. These methods provide a simple, rapid, and accurate alternative to thin-layer chromatography for determination of phospholipids in amniotic fluid for assessment of fetal lung maturity.

  2. Regulation of hepatic lipase activity by sphingomyelin in plasma lipoproteins.

    Science.gov (United States)

    Yang, Peng; Subbaiah, Papasani V

    2015-10-01

    Hepatic lipase (HL) is an important enzyme in the clearance of triacylglycerol (TAG) from the circulation, and has been proposed to have pro-atherogenic as well as anti-atherogenic properties. It hydrolyzes both phospholipids and TAG of lipoproteins, and its activity is negatively correlated with HDL levels. Although it is known that HL acts preferentially on HDL lipids, the basis for this specificity is not known, since it does not require any specific apoprotein for activity. In this study, we tested the hypothesis that sphingomyelin (SM), whose concentration is much higher in VLDL and LDL compared to HDL, is an inhibitor of HL, and that this could explain the lipoprotein specificity of the enzyme. The results presented show that the depletion of SM from normal lipoproteins activated the HL roughly in proportion to their SM content. SM depletion stimulated the hydrolysis of both phosphatidylcholine (PC) and TAG, although the PC hydrolysis was stimulated more. In the native lipoproteins, HL showed specificity for PC species containing polyunsaturated fatty acids at sn-2 position, and produced more unsaturated lyso PC species. The enzyme also showed preferential hydrolysis of certain TAG species over others. SM depletion affected the specificity of the enzyme towards PC and TAG species modestly. These results show that SM is a physiological inhibitor of HL activity in lipoproteins and that the specificity of the enzyme towards HDL is at least partly due to its low SM content. Published by Elsevier B.V.

  3. Relationships Between Base-Catalyzed Hydrolysis Rates or Glutathione Reactivity for Acrylates and Methacrylates and Their NMR Spectra or Heat of Formation

    Directory of Open Access Journals (Sweden)

    Yoshinori Kadoma

    2012-05-01

    Full Text Available The NMR chemical shift, i.e., the π-electron density of the double bond, of acrylates and methacrylates is related to the reactivity of their monomers. We investigated quantitative structure-property relationships (QSPRs between the base-catalyzed hydrolysis rate constants (k1 or the rate constant with glutathione (GSH (log kGSH for acrylates and methacrylates and the 13C NMR chemical shifts of their α,β-unsaturated carbonyl groups (δCα and δCβ or heat of formation (Hf calculated by the semi-empirical MO method. Reported data for the independent variables were employed. A significant linear relationship between k1 and δCβ, but not δCα, was obtained for methacrylates (r2 = 0.93, but not for acrylates. Also, a significant relationship between k1 and Hf was obtained for both acrylates and methacrylates (r2 = 0.89. By contrast, log kGSH for acrylates and methacrylates was linearly related to their δCβ (r2 = 0.99, but not to Hf. These findings indicate that the 13C NMR chemical shifts and calculated Hf values for acrylates and methacrylates could be valuable for estimating the hydrolysis rate constants and GSH reactivity of these compounds. Also, these data for monomers may be an important tool for examining mechanisms of reactivity.

  4. Study on the Hydrolysis Kinetics of Xylan on Different Acid Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Na, Byeong-Il; Lee, Jae-Won [Chonnam National University, Gwangju (Korea, Republic of)

    2014-04-15

    In this study, we investigated kinetic model for the acid-catalyzed xylan hydrolysis at temperature 120-150 .deg. C. Also, we analyzed the kinetic parameters for xylose production and furfural decomposition. The hydrolysis of xylan and the degradation of xylose were promoted by high reaction temperature and acid concentration. The optimal hydrolysis condition for the highest reaction rate constants (k{sub 1}) was different depending on the acid catalysts. Among sulfuric, oxalic and maleic acid, the xylan reaction rate constants (k{sub 1}) to xylose had the highest value of 0.0241 min{sup -1} when 100 mM sulfuric acid was used at 120 .deg. C. However, sulfuric acid induced more xylose degradation compared to oxalic and maleic acid hydrolysis. The activation energy for xylan degradation was the highest when sulfuric acid was used.

  5. Electron transfer precedes ATP hydrolysis during nitrogenase catalysis.

    Science.gov (United States)

    Duval, Simon; Danyal, Karamatullah; Shaw, Sudipta; Lytle, Anna K; Dean, Dennis R; Hoffman, Brian M; Antony, Edwin; Seefeldt, Lance C

    2013-10-08

    The biological reduction of N2 to NH3 catalyzed by Mo-dependent nitrogenase requires at least eight rounds of a complex cycle of events associated with ATP-driven electron transfer (ET) from the Fe protein to the catalytic MoFe protein, with each ET coupled to the hydrolysis of two ATP molecules. Although steps within this cycle have been studied for decades, the nature of the coupling between ATP hydrolysis and ET, in particular the order of ET and ATP hydrolysis, has been elusive. Here, we have measured first-order rate constants for each key step in the reaction sequence, including direct measurement of the ATP hydrolysis rate constant: kATP = 70 s(-1), 25 °C. Comparison of the rate constants establishes that the reaction sequence involves four sequential steps: (i) conformationally gated ET (kET = 140 s(-1), 25 °C), (ii) ATP hydrolysis (kATP = 70 s(-1), 25 °C), (iii) Phosphate release (kPi = 16 s(-1), 25 °C), and (iv) Fe protein dissociation from the MoFe protein (kdiss = 6 s(-1), 25 °C). These findings allow completion of the thermodynamic cycle undergone by the Fe protein, showing that the energy of ATP binding and protein-protein association drive ET, with subsequent ATP hydrolysis and Pi release causing dissociation of the complex between the Fe(ox)(ADP)2 protein and the reduced MoFe protein.

  6. Electron transfer precedes ATP hydrolysis during nitrogenase catalysis

    Science.gov (United States)

    Duval, Simon; Danyal, Karamatullah; Shaw, Sudipta; Lytle, Anna K.; Dean, Dennis R.; Hoffman, Brian M.; Antony, Edwin; Seefeldt, Lance C.

    2013-01-01

    The biological reduction of N2 to NH3 catalyzed by Mo-dependent nitrogenase requires at least eight rounds of a complex cycle of events associated with ATP-driven electron transfer (ET) from the Fe protein to the catalytic MoFe protein, with each ET coupled to the hydrolysis of two ATP molecules. Although steps within this cycle have been studied for decades, the nature of the coupling between ATP hydrolysis and ET, in particular the order of ET and ATP hydrolysis, has been elusive. Here, we have measured first-order rate constants for each key step in the reaction sequence, including direct measurement of the ATP hydrolysis rate constant: kATP = 70 s−1, 25 °C. Comparison of the rate constants establishes that the reaction sequence involves four sequential steps: (i) conformationally gated ET (kET = 140 s−1, 25 °C), (ii) ATP hydrolysis (kATP = 70 s−1, 25 °C), (iii) Phosphate release (kPi = 16 s−1, 25 °C), and (iv) Fe protein dissociation from the MoFe protein (kdiss = 6 s−1, 25 °C). These findings allow completion of the thermodynamic cycle undergone by the Fe protein, showing that the energy of ATP binding and protein–protein association drive ET, with subsequent ATP hydrolysis and Pi release causing dissociation of the complex between the Feox(ADP)2 protein and the reduced MoFe protein. PMID:24062462

  7. Annexins as organizers of cholesterol- and sphingomyelin-enriched membrane microdomains in Niemann-Pick type C disease.

    Science.gov (United States)

    Domon, Magdalena; Nasir, Mehmet Nail; Matar, Gladys; Pikula, Slawomir; Besson, Françoise; Bandorowicz-Pikula, Joanna

    2012-06-01

    Growing evidence suggests that membrane microdomains enriched in cholesterol and sphingomyelin are sites for numerous cellular processes, including signaling, vesicular transport, interaction with pathogens, and viral infection, etc. Recently some members of the annexin family of conserved calcium and membrane-binding proteins have been recognized as cholesterol-interacting molecules and suggested to play a role in the formation, stabilization, and dynamics of membrane microdomains to affect membrane lateral organization and to attract other proteins and signaling molecules onto their territory. Furthermore, annexins were implicated in the interactions between cytosolic and membrane molecules, in the turnover and storage of cholesterol and in various signaling pathways. In this review, we focus on the mechanisms of interaction of annexins with lipid microdomains and the role of annexins in membrane microdomains dynamics including possible participation of the domain-associated forms of annexins in the etiology of human lysosomal storage disease called Niemann-Pick type C disease, related to the abnormal storage of cholesterol in the lysosome-like intracellular compartment. The involvement of annexins and cholesterol/sphingomyelin-enriched membrane microdomains in other pathologies including cardiac dysfunctions, neurodegenerative diseases, obesity, diabetes mellitus, and cancer is likely, but is not supported by substantial experimental observations, and therefore awaits further clarification.

  8. Heteropoly acid catalyzed hydrolysis of glycogen to glucose

    International Nuclear Information System (INIS)

    Klein, Miri; Pulidindi, Indra Neel; Perkas, Nina; Gedanken, Aharon

    2015-01-01

    Complete conversion of glycogen to glucose is achieved by using H 3 PW 12 O 40 ·nH 2 O (HPW) and H 4 SiW 12 O 40 ·nH 2 O (HSiW) as catalysts for the hydrolysis under optimized hydrothermal conditions (mass fraction of catalyst 2.4%, 373 K and 2 h reaction time). The reusability of the catalyst (HPW) was demonstrated. In addition to carrying out the glycogen hydrolysis in an autoclave, other novel methods such as microwave irradiation and sonication have also been investigated. At higher mass fraction of the heteropoly acids (10.5%), glycogen could be completely converted to glucose under microwave irradiation. Sonication of an aqueous solution of glycogen in the presence of HPW and HSiW also yielded glucose. Thus, heteropoly acids are efficient, environmentally friendly and reusable catalysts for the conversion of glycogen to glucose. - Highlights: • Hydrothermal, microwave and sonication based methods of hydrolysis. • Heteropoly acids are green catalysts for glycogen hydrolysis. • Glycogen from cyanobacteria is demonstrated as a potential feedstock for glucose

  9. Catalytic hydrolysis of s-triazine compounds over AlzO3

    NARCIS (Netherlands)

    Zhan, Z.; Zhan, Zhaoqi; Müllner, Martin; Lercher, J.A.

    1996-01-01

    Hydrolysis of cyanuric acid, melamine, melem, atrazine and melamine-formaldehyde resin was found to be catalyzed by an A12O3 catatyst. The reactions occur irreversibly with cleavage of the s-triazine ring between 240 and 450°C. The s-triazine-ring is hydrolyzed to ammonia and carbon dioxide, and the

  10. 21 CFR 862.1455 - Lecithin/sphingomyelin ratio in amniotic fluid test system.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Lecithin/sphingomyelin ratio in amniotic fluid... Clinical Chemistry Test Systems § 862.1455 Lecithin/sphingomyelin ratio in amniotic fluid test system. (a) Identification. A lecithin/sphingomyelin ratio in amniotic fluid test system is a device intended to measure the...

  11. The acid-catalyzed hydrolysis of an α-pinene-derived organic nitrate: kinetics, products, reaction mechanisms, and atmospheric impact

    Science.gov (United States)

    Rindelaub, Joel D.; Borca, Carlos H.; Hostetler, Matthew A.; Slade, Jonathan H.; Lipton, Mark A.; Slipchenko, Lyudmila V.; Shepson, Paul B.

    2016-12-01

    data, product identification confirms that a unimolecular specific acid-catalyzed mechanism is responsible for organic nitrate hydrolysis under acidic conditions. The free energies and enthalpies of the isobutyl nitrate hydrolysis intermediates and products were calculated using a hybrid density functional (ωB97X-V) to support the proposed mechanisms. These findings provide valuable information regarding the organic nitrate hydrolysis mechanism and its contribution to the fate of atmospheric NOx, aerosol phase processing, and BSOA composition.

  12. Rh(III)-catalyzed olefination of N-sulfonyl imines: synthesis of ortho-olefinated benzaldehydes.

    Science.gov (United States)

    Zhang, Tao; Wu, Lamei; Li, Xingwei

    2013-12-20

    Rh(III)-catalyzed olefination of N-sulfonyl imines using acrylates and styrenes has been achieved for the synthesis of ortho-olefinated benaldehydes. This reaction proceeds via a chelation assisted C-H olefination/in situ hydrolysis process.

  13. Furfural production from fruit shells by acid-catalyzed hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Demirbas, A. [Selcuk Univ., Konya (Turkey). Dept. of Chemical Engineering

    2006-01-21

    Pentosans are hydrolyzed to pentoses by dilute mineral acid hydrolysis. The main source of pentosans is hemicelluloses. Furfural can be produced by the acid hydrolysis of pentosan from fruit shells such as hazelnut, sunflower, walnut, and almond of agricultural wastes. Further dehydration reactions of the pentoses yield furfural. The hydrolysis of each shell sample was carried out in dilute sulfuric acid (0.05 to 0.200 mol/l), at high temperature (450-525 K), and short reaction times (from 30 to 600 s). (author)

  14. Possible roles of long-chain sphingomyelines and sphingomyelin synthase 2 in mouse macrophage inflammatory response

    International Nuclear Information System (INIS)

    Sakamoto, Hideaki; Yoshida, Tetsuya; Sanaki, Takao; Shigaki, Shuhei; Morita, Hirotoshi; Oyama, Miki; Mitsui, Masaru; Tanaka, Yoshikazu; Nakano, Toru; Mitsutake, Susumu; Igarashi, Yasuyuki; Takemoto, Hiroshi

    2017-01-01

    To evaluate the precise role of sphingomyelin synthase 2 (SMS2) in sphingomyelin (SM) metabolism and their anti-inflammatory properties, we analyzed species of major SM and ceramide (Cer) (18:1, 18:0 sphingoid backbone, C14 - C26 N-acyl part) in SMS2 knockout and wild-type mouse plasma and liver using HPLC-MS. SMS2 deficiency significantly decreased very long chain SM (SM (d18:1/22:0) and SM (d18:1/24:0 or d18:0/24:1)) and increased very long chain Cer (Cer (d18:1/24:0 or d18:0/24:1) and Cer (d18:1/24:1)), but not long chain SM (SM (d18:1/16:0), SM (d18:1/18:0 or d18:0/18:1) and SM (d18:1/18:1)) in plasma. To examine the effects of SM on inflammation, we studied the role of very long chain SM in macrophage activation. Addition of SM (d18:1/24:0) strongly upregulated several macrophage activation markers, SM (d18:1/6:0) and Cer (d18:1/24:0) however, did not. It was suggested that very long chain SM but not long chain SM were decreased in SMS2-deficient mice liver and plasma. And the exogenously added very long chain SM (d18:1/24:0) could activate macrophages directly, suggesting a novel role of plasma very long chain SM in modulating macrophage activation and resulting inflammation. - Highlights: • Very long-chain SM species were decreased in SMS2 knockout mouse plasma and liver. • Very long-chain ceramide species were increased in SMS2 knockout mouse plasma. • SMS2 deficiency diminished the inflammatory response of macrophages. • Very long-chain SM enhanced ICAM1 and iNOS expression in peritoneal macrophages.

  15. Tracking cholesterol/sphingomyelin-rich membrane domains with the ostreolysin A-mCherry protein.

    Directory of Open Access Journals (Sweden)

    Matej Skočaj

    Full Text Available Ostreolysin A (OlyA is an ∼15-kDa protein that has been shown to bind selectively to membranes rich in cholesterol and sphingomyelin. In this study, we investigated whether OlyA fluorescently tagged at the C-terminal with mCherry (OlyA-mCherry labels cholesterol/sphingomyelin domains in artificial membrane systems and in membranes of Madin-Darby canine kidney (MDCK epithelial cells. OlyA-mCherry showed similar lipid binding characteristics to non-tagged OlyA. OlyA-mCherry also stained cholesterol/sphingomyelin domains in the plasma membranes of both fixed and living MDCK cells, and in the living cells, this staining was abolished by pretreatment with either methyl-β-cyclodextrin or sphingomyelinase. Double labelling of MDCK cells with OlyA-mCherry and the sphingomyelin-specific markers equinatoxin II-Alexa488 and GST-lysenin, the cholera toxin B subunit as a probe that binds to the ganglioside GM1, or the cholesterol-specific D4 domain of perfringolysin O fused with EGFP, showed different patterns of binding and distribution of OlyA-mCherry in comparison with these other proteins. Furthermore, we show that OlyA-mCherry is internalised in living MDCK cells, and within 90 min it reaches the juxtanuclear region via caveolin-1-positive structures. No binding to membranes could be seen when OlyA-mCherry was expressed in MDCK cells. Altogether, these data clearly indicate that OlyA-mCherry is a promising tool for labelling a distinct pool of cholesterol/sphingomyelin membrane domains in living and fixed cells, and for following these domains when they are apparently internalised by the cell.

  16. Unexpected Reaction Pathway for butyrylcholinesterase-catalyzed inactivation of “hunger hormone” ghrelin

    Science.gov (United States)

    Yao, Jianzhuang; Yuan, Yaxia; Zheng, Fang; Zhan, Chang-Guo

    2016-02-01

    Extensive computational modeling and simulations have been carried out, in the present study, to uncover the fundamental reaction pathway for butyrylcholinesterase (BChE)-catalyzed hydrolysis of ghrelin, demonstrating that the acylation process of BChE-catalyzed hydrolysis of ghrelin follows an unprecedented single-step reaction pathway and the single-step acylation process is rate-determining. The free energy barrier (18.8 kcal/mol) calculated for the rate-determining step is reasonably close to the experimentally-derived free energy barrier (~19.4 kcal/mol), suggesting that the obtained mechanistic insights are reasonable. The single-step reaction pathway for the acylation is remarkably different from the well-known two-step acylation reaction pathway for numerous ester hydrolysis reactions catalyzed by a serine esterase. This is the first time demonstrating that a single-step reaction pathway is possible for an ester hydrolysis reaction catalyzed by a serine esterase and, therefore, one no longer can simply assume that the acylation process must follow the well-known two-step reaction pathway.

  17. Toward Efficient Palladium-Catalyzed Allylic C-H Alkylation

    DEFF Research Database (Denmark)

    Jensen, Thomas; Fristrup, Peter

    2009-01-01

    Recent breakthroughs have proved that direct palladium (II)-catalyzed allylic C-H alkylation can be achieved. This new procedure shows that the inherent requirement for a leaving group in the Tsuji-Trost palladium-catalyzed allylic alkylation can be lifted. These initial reports hold great promise...... for the development of allylic C-H alkylation into a widely applicable methodology, thus providing a means to enhance synthetic efficiency in these reactions....

  18. [3H]Indole-3-acetyl-myo-inositol hydrolysis by extracts of Zea mays L. vegetative tissue

    Science.gov (United States)

    Hall, P. J.; Bandurski, R. S.

    1986-01-01

    [3H]Indole-3-acetyl-myo-inositol was hydrolyzed by buffered extracts of acetone powders prepared from 4 day shoots of dark grown Zea mays L. seedlings. The hydrolytic activity was proportional to the amount of extract added and was linear for up to 6 hours at 37 degrees C. Boiled or alcohol denatured extracts were inactive. Analysis of reaction mixtures by high performance liquid chromatography demonstrated that not all isomers of indole-3-acetyl-myo-inositol were hydrolyzed at the same rate. Buffered extracts of acetone powders were prepared from coleoptiles and mesocotyls. The rates of hydrolysis observed with coleoptile extracts were greater than those observed with mesocotyl extracts. Active extracts also catalyzed the hydrolysis of esterase substrates such as alpha-naphthyl acetate and the methyl esters of indoleacetic acid and naphthyleneacetic acid. Attempts to purify the indole-3-acetyl-myo-inositol hydrolyzing activity by chromatographic procedures resulted in only slight purification with large losses of activity. Chromatography over hydroxylapatite allowed separation of two enzymically active fractions, one of which catalyzed the hydrolysis of both indole-3-acetyl-myo-inositol and esterase substrates. With the other enzymic hydrolysis of esterase substrates was readily demonstrated, but no hydrolysis of indole-3-acetyl-myo-inositol was ever detected.

  19. [3H]Indole-3-acetyl-myo-inositol hydrolysis by extracts of Zea mays L. vegetative tissue

    International Nuclear Information System (INIS)

    Hall, P.J.; Bandurski, R.S.

    1986-01-01

    [ 3 H]Indole-3-acetyl-myo-inositol was hydrolyzed by buffered extracts of acetone powders prepared from 4 day shoots of dark grown Zea mays L. seedlings. The hydrolytic activity was proportional to the amount of extract added and was linear for up to 6 hours at 37 0 C. Boiled or alcohol denatured extracts were inactive. Analysis of reaction mixtures by high performance liquid chromatography demonstrated that not all isomers of indole-3-acetyl-myo-inositol were hydrolyzed at the same rate. Buffered extracts of acetone powders were prepared from coleoptiles and mesocotyls. The rates of hydrolysis observed with coleoptile extracts were greater than those observed with mesocotyl extracts. Active extracts also catalyzed the hydrolysis of esterase substrates such as α-naphthyl acetate and the methyl esters of indoleacetic acid and naphthyleneacetic acid. Attempts to purify the indole-3-acetyl-myo-inositol hydrolyzing activity by chromatographic procedures resulted in only slight purification with large losses of activity. Chromatography over hydroxylapatite allowed separation of two enzymically active fractions, one of which catalyzed the hydrolysis of both indole-3-acetyl-myo-inositol and esterase substrates. With the other fraction enzymic hydrolysis of esterase substrates was readily demonstrated, but no hydrolysis of indole-3-acetyl-myo-inositol was ever detected

  20. Hydrolysis of solid ammonia borane

    Energy Technology Data Exchange (ETDEWEB)

    Demirci, Umit B.; Miele, Philippe [Universite Lyon 1, CNRS, UMR 5615, Laboratoire des Multimateriaux et Interfaces, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne (France)

    2010-07-01

    Ammonia borane NH{sub 3}BH{sub 3} is a promising hydrogen storage material by virtue of a theoretical gravimetric hydrogen storage capacity (GHSC) of 19.5 wt%. However, stored hydrogen has to be effectively released, one way of recovering this hydrogen being the metal-catalyzed hydrolysis. The present study focuses on CoCl{sub 2}-catalyzed hydrolysis of NH{sub 3}BH{sub 3} with the concern of improving the effective GHSC of the system NH{sub 3}BH{sub 3}-H{sub 2}O. For that, NH{sub 3}BH{sub 3} is stored as a solid and H{sub 2}O is provided in stoichiometric amount. By this way, an effective GHSC of 7.8 wt% has been reached at 25 C. To our knowledge, it is the highest value ever reported. Besides, one of the highest hydrogen generation rates (HGRs, 21 ml(H{sub 2}) min{sup -1}) has been found. In parallel, the increases of the water amount and temperature have been studied and the reaction kinetics has been determined. Finally, it has been observed that some NH{sub 3} release, what is detrimental for a fuel cell. To summarize, high performances in terms of GHSCs and HGRs can be reached with NH{sub 3}BH{sub 3} and since research devoted to this boron hydride is at the beginning we may be confident in making it viable in a near future. (author)

  1. Lipase kinetics: hydrolysis of triacetin by lipase from Candida cylindracea in a hollow-fiber membrane reactor

    NARCIS (Netherlands)

    Guit, R.P.M.; Kloosterman, M.; Meindersma, G.W.; Mayer, M.; Meijer, E.M.

    1991-01-01

    The aptitude of a hollow-fiber membrane reactor to det. lipase kinetics was investigated using the hydrolysis of triacetin catalyzed by lipase from C. cylindracea as a model system. The binding of the lipase to the membrane appears not to be very specific (surface adsorption), and probably its

  2. Adenovirus-mediated sphingomyelin synthase 2 increases atherosclerotic lesions in ApoE KO mice

    Directory of Open Access Journals (Sweden)

    Zhao Yarui

    2011-01-01

    Full Text Available Abstract Background Sphingomyelin synthase 2 (SMS2 contributes to de novo sphingomyelin (SM biosynthesis. Its activity is related to SM levels in the plasma and the cell membrane. In this study, we investigated the possibility of a direct relationship between SMS and atherosclerosis. Methods The Adenovirus containing SMS2 gene was given into 10-week ApoE KO C57BL/6J mice by femoral intravenous injection. In the control group, the Adenovirus containing GFP was given. To confirm this model, we took both mRNA level examination (RT-PCR and protein level examination (SMS activity assay. Result We generated recombinant adenovirus vectors containing either human SMS2 cDNA (AdV-SMS2 or GFP cDNA (AdV-GFP. On day six after intravenous infusion of 2 × 1011 particle numbers into ten-week-old apoE KO mice, AdV-SMS2 treatment significantly increased liver SMS2 mRNA levels and SMS activity (by 2.7-fold, 2.3-fold, p Conclusions Our results present direct morphological evidence for the pro-atherogenic capabilities of SMS2. SMS2 could be a potential target for treating atherosclerosis.

  3. Electrochemical Cobalt-Catalyzed C-H Activation.

    Science.gov (United States)

    Sauermann, Nicolas; Meyer, Tjark H; Ackermann, Lutz

    2018-06-19

    Carbon-heteroatom bonds represent omnipresent structural motifs of the vast majority of functionalized materials and bioactive compounds. C-H activation has emerged as arguably the most efficient strategy to construct C-Het bonds. Despite of major advances, these C-H transformations were largely dominated by precious transition metal catalysts, in combination with stoichiometric, toxic metal oxidants. Herein, we discuss the recent evolution of cobalt-catalyzed C-H activations that enable C-Het formations with electricity as the sole sustainable oxidant until May 2018. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Optimization of H2SO4-catalyzed hydrothermal pretreatment of rapeseed straw for bioconversion to ethanol

    DEFF Research Database (Denmark)

    Xuebin, Lu; Zhang, Y.; Angelidaki, Irini

    2009-01-01

    A central composite design of response surface method was used to optimize H2SO4-catalyzed hydrothermal pretreatment of rapeseed straw, in respect to acid concentration (0.5-2%), treatment time (5-20 min) and solid content (10-20%) at 180 degrees C. Enzymatic hydrolysis and fermentation were also...... content for 10 min at 180 degrees C was found to be the most optimal condition for pretreatment of rapeseed straw for ethanol production. After pretreatment at the optimal condition and enzymatic hydrolysis, 75.12% total xylan and 63.17% total glucan were converted to xylose and glucose, respectively...

  5. Lipase applications in oil hydrolysis with a case study on castor oil: a review.

    Science.gov (United States)

    Goswami, Debajyoti; Basu, Jayanta Kumar; De, Sirshendu

    2013-03-01

    Lipase (triacylglycerol acylhydrolase) is a unique enzyme which can catalyze various types of reactions such as hydrolysis, esterification, alcoholysis etc. In particular, hydrolysis of vegetable oil with lipase as a catalyst is widely studied. Free lipase, lipase immobilized on suitable support, lipase encapsulated in a reverse micelle and lipase immobilized on a suitable membrane to be used in membrane reactor are the most common ways of employing lipase in oil hydrolysis. Castor oil is a unique vegetable oil as it contains high amounts (90%) of a hydroxy monounsaturated fatty acid named ricinoleic acid. This industrially important acid can be obtained by hydrolysis of castor oil. Different conventional hydrolysis processes have certain disadvantages which can be avoided by a lipase-catalyzed process. The degree of hydrolysis varies widely for different lipases depending on the operating range of process variables such as temperature, pH and enzyme loading. Immobilization of lipase on a suitable support can enhance hydrolysis by suppressing thermal inactivation and estolide formation. The presence of metal ions also affects lipase-catalyzed hydrolysis of castor oil. Even a particular ion has different effects on the activity of different lipases. Hydrophobic organic solvents perform better than hydrophilic solvents during the reaction. Sonication considerably increases hydrolysis in case of lipolase. The effects of additives on the same lipase vary with their types. Nonionic surfactants enhance hydrolysis whereas cationic and anionic surfactants decrease it. A single variable optimization method is used to obtain optimum conditions. In order to eliminate its disadvantages, a statistical optimization method is used in recent studies. Statistical optimization shows that interactions between any two of the following pH, enzyme concentration and buffer concentration become significant in presence of a nonionic surfactant named Span 80.

  6. Hydrolysis of palm oil catalyzed by acid%棕榈油的酸催化水解工艺研究

    Institute of Scientific and Technical Information of China (English)

    张玲玲; 王晖

    2015-01-01

    以棕榈油为原料进行常压酸催化水解工艺研究。考察了反应时间、反应温度、催化剂用量、油水质量比及乳化剂用量对棕榈油水解反应的影响,得出棕榈油一次酸催化水解的最佳反应条件:反应时间7 h,反应温度100℃,催化剂浓硫酸用量7.5%,油水质量比1∶1,乳化剂磺酸用量0.5%;在最佳反应条件下棕榈油水解产物酸值(KOH)为192.77 mg/g,水解率达到91.96%。并研究出一套循环水解的工艺流程,实现油脂水解产物的循环利用,提高了水相中甘油的含量。%The hydrolysis of palm oil catalyzed by acid was studied. The effects of reaction time,reaction temperature,catalyst dosage,mass ratio of oil to water and emulsifier dosage on the hydrolysis of palm oil were investigated. The optimal reaction conditions of palm oil hydrolysis were obtained as follows:reaction time 7 h,reaction temperature 100℃,mass ratio of oil to water 1∶1,dosage of sulfonic acid used as emul-sifier 0. 5% and catalyst( concentrated sulfonic acid) dosage 7. 5%. Under the optimal reaction condi-tions,the acid value of the hydrolysates was up to 192. 77 mgKOH/g and the hydrolysis rate of palm oil was 91. 96%. A circulated hydrolysis process was designed, then the recycling of hydrolysates was real-ized,and the content of glycerin in the aqueous phase increased.

  7. Nuclear Lipid Microdomain as Place of Interaction between Sphingomyelin and DNA during Liver Regeneration

    Directory of Open Access Journals (Sweden)

    Samuela Cataldi

    2013-03-01

    Full Text Available Nuclear sphingomyelin is a key molecule for cell proliferation. This molecule is organized with cholesterol and proteins to form specific lipid microdomains bound to the inner nuclear membrane where RNA is synthesized. Here, we have reported the ability of the sphingomyelin present in the nuclear microdomain to bind DNA and regulate its synthesis, and to highlight its role in cell proliferation induced by partial hepatectomy. During G1/S transition of the cell cycle, sphingomyelin and DNA content is very high and it is strongly reduced after exogenous sphingomyelinase treatment. During the S-phase of the cell cycle, the stimulation of sphingomyelinase and inhibition of sphingomyelin–synthase are accompanied by the DNA synthesis start. To assess the specificity of the results, experiments were repeated with trifluoperazine, a drug known to affect the synthesis of lipids and DNA and to stimulate sphingomyelinase activity. The activity of sphingomyelinase is stimulated in the first hour after hepatectomy and sphingomyelin–DNA synthesis is strongly attenuated. It may be hypothesized that the nuclear microdomain represents a specific area of the inner nuclear membrane that acts as an active site of chromatin anchorage thanks to the stabilizing action of sphingomyelin. Thus, sphingomyelin metabolism in nuclear lipid microdomains is suggested to regulate cell proliferation.

  8. Kinetic α secondary deuterium isotope effects for O-ethyl S-phenyl benzaldehyde acetal hydrolysis

    International Nuclear Information System (INIS)

    Ferraz, J.P.; Cordes, E.H.

    1979-01-01

    The rate of hydrolysis of O-ethyl S-phenyl benzaldehyde acetal at 25 0 C in 20% dioxane--80% water is independent of pH over the range pH6-12; k/sub obsd/ = 1.9 x 10 -7 s -1 . Under more acidic conditions, the rate increases linearly with the activity of the hydrated proton; k 2 = 2.95 x 10 -2 M -1 s -1 . The kinetic α secondary deuterium isotope effect for acid-catalyzed hydrolysis of O-ethyl S-phenyl benzaldehyde acetal, measured at 25 0 C in 20% aqueous dioxane containing 0.05 M HCl, is k/sub H//k/sub D/ = 1.038 +- 0.008, a value consistent with a transition state in which the C--S bond is stretched rather little. In contrast, the corresponding isotope effect for the pH-independent hydrolysis of this substrate, measured at 42.5 0 C in 20% dioxane, is 1.13 +- 0.02, a value consistent with complete C--S bond cleavage in the transition state and rate-determining diffusion apart of the ion-pair formed as the initial intermediate, in accord with the suggestion of Jensen and Jencks. 1 figure, 4 tables

  9. Neomysin inhibits Ca2+-stimulated phosphatidylinositol hydrolysis and protects cultured rat cardiomyocytes from Ca2+-dependent cell injury

    International Nuclear Information System (INIS)

    Babson, J.R.; Dougherty, J.M.

    1991-01-01

    Exposure of cultured rat cardiomyocytes to ionomycin and extracellular Ca 2+ leads to a rapid, sustained increase in intracellular free Ca 2+ as monitored by Ca 2+ -dependent phosphorylase a activation and to a subsequent loss of cardiomyocyte viability as determined by lactate dehydrogenase (LDH) leakage. The intracellular free Ca 2+ increase coincided with a rapid hydrolysis of phosphatidylinositol that preceded cell death. Phosphatidylinositol hydrolysis was monitored by the release of radiolabeled phosphoinositides from cardiomyocytes prelabeled with [2- 3 H]-myo-inositol. Neomycin, a known inhibitor of phospholipase C, inhibited the phosphatidylinositol hydrolysis and markedly reduced the extent of cell injury. Inhibitors of other Ca 2+ -activated processes, including intracellular proteases and phospholipase A 2 , had no effect on ionomycin-mediated cell injury. These data suggest that ionomycin-induced Ca 2+ -dependent cell injury in cultured cardiomyocytes may be due in part to the stimulation of phosphatidylinositol hydrolysis, presumably catalyzed by a Ca 2+ -dependent phospholipase C

  10. Cholinesterase catalyzed hydrolysis of O-acyl derivatives of serotonin

    International Nuclear Information System (INIS)

    Makhaeva, G.F.; Suvorov, N.N.; Ginodman, L.N.; Antonov, V.K.; AN SSSR, Moscow. Inst. Bioorganicheskoj Khimii)

    1977-01-01

    Hydrolysis of O acyl serotonin derivatives containing the residues of monocarbon dicarbon and amino acids under the effect of horse serum butyryl cholinesterase and bull erythrocytic acetylcholinesterase has been studied. It has been established, that acetylcholinesterase hydrolizes O acetylserotonin only; butyrylcholinesterase hydrolizes all the compounds investigated, except for 5,5'-terephthaloildioxytriptamine. The kinetic parameters of hydrolysis were determined. O acyl serotonin derivatives turned out good substrates of butylrylcholinesterase; serotonin and 5.5'-terephtaloildioxytriptamine are effective competitine inhibitors of the enzyme. Estimating of resistance of O acyl serotonin derivatines to blood cholinesterase effect under physiological conditions shows that the compounds investigated with the exception of 5,5'-terephthaloildioxytriptamine must be quickly hydrolyzed under butyrylcholinesterase action. 5,5'-terephthaloildioxytriptamine is suggested as a radioprotective preparation with the prolonged effect, which agrees with the biological test results

  11. On-line characterization using ultrasound of pectin hydrolysis catalyzed by the enzyme pectinmethylesterase

    Science.gov (United States)

    Aparicio, C.; Resa, P.; Sierra, C.; Elvira, L.

    2012-12-01

    The major problem in the fruit juice industry is associated with juice quality deterioration due to the cloud loss of juice concentrates by the enzymatic reaction of pectinmethylesterase enzyme (PME, EC 3.1.1.11). During pectin hydrolysis, pectin and water are transformed into polygalacturonic acid (pectate) and methanol by the action of PME. In this work, a low-intensity ultrasonic technique is used to monitor this enzymatic reaction, with PME both from orange peel and from Aspergillus niger. Changes in sound velocity during pectin hydrolysis (1% concentration of pectin, T = 30°C and pH = 4.5 and 7) with 0.25 ml of enzyme solution (PME) have been measured using a through-transmission technique. Sound velocity decreases as pectin is transformed into pectate and methanol and at the end of the process, the change in sound velocity reaches 0.3 m/s with PME from orange peel and 0.33 m/s with PME from Aspergillus niger.

  12. On-line characterization using ultrasound of pectin hydrolysis catalyzed by the enzyme pectinmethylesterase

    International Nuclear Information System (INIS)

    Aparicio, C; Resa, P; Sierra, C; Elvira, L

    2012-01-01

    The major problem in the fruit juice industry is associated with juice quality deterioration due to the cloud loss of juice concentrates by the enzymatic reaction of pectinmethylesterase enzyme (PME, EC 3.1.1.11). During pectin hydrolysis, pectin and water are transformed into polygalacturonic acid (pectate) and methanol by the action of PME. In this work, a low-intensity ultrasonic technique is used to monitor this enzymatic reaction, with PME both from orange peel and from Aspergillus niger. Changes in sound velocity during pectin hydrolysis (1% concentration of pectin, T = 30°C and pH = 4.5 and 7) with 0.25 ml of enzyme solution (PME) have been measured using a through-transmission technique. Sound velocity decreases as pectin is transformed into pectate and methanol and at the end of the process, the change in sound velocity reaches 0.3 m/s with PME from orange peel and 0.33 m/s with PME from Aspergillus niger.

  13. The rabbit liver microsomal biotransformation of 1,1-dialkylethylenes: enantioface selection of epoxidation and enantioselectivity of epoxide hydrolysis.

    Science.gov (United States)

    Bellucci, G; Chiappe, C; Cordoni, A; Marioni, F

    1994-01-01

    The rabbit liver microsomal biotransformation of alpha-methylstyrene (1a), 2-methyl-1-hexene (1b), 2,4,4-trimethyl-1-pentene (1c), and 1,3,3-trimethyl-1-butene (1d) has been investigated with the aim at establishing the enantioface selection of the cytochrome P-450-promoted epoxidation of the double bond and the enantioselectivity of microsomal epoxide hydrolase(mEH)-catalyzed hydrolysis of the resulting epoxides. GLC on a Chiraldex G-TA (ASTEC) column was used to determine the enantiomeric composition of the products. The epoxides 2 first produced in incubations carried out in the presence of an NADPH regenerating system were not detected, being rapidly hydrolyzed by mEH to diols 3. The enantiomeric composition of the latter showed that no enantioface selection occurred in the epoxidation of 1c and 1d, and a very low (8%) ee of the (R)-epoxide was formed from 1b. Incubation of racemic epoxides 2b-d with the microsomal fraction showed that the mEH-catalyzed hydrolysis of 2c and 2d was practically nonenantioselective, while that of 2b exhibited a selectivity E = 4.9 favoring the hydrolysis of the (S)-enantiomer. A comparison of these results with those previously obtained for linear and branched chain alkyl monosubstituted oxiranes shows that the introduction of the second alkyl substituent suppresses the selectivity of the mEH reaction of the latter and reverses that of the former substrates.

  14. Hydrolysis of Selected Tropical Plant Wastes Catalyzed by a Magnetic Carbonaceous Acid with Microwave

    Science.gov (United States)

    Su, Tong-Chao; Fang, Zhen; Zhang, Fan; Luo, Jia; Li, Xing-Kang

    2015-12-01

    In this study, magnetic carbonaceous acids were synthesized by pyrolysis of the homogeneous mixtures of glucose and magnetic Fe3O4 nanoparticles, and subsequent sulfonation. The synthesis conditions were optimized to obtain a catalyst with both high acid density (0.75 mmol g-1) and strong magnetism [magnetic saturation, Ms = 19.5 Am2 kg-1]. The screened catalyst (C-SO3H/Fe3O4) was used to hydrolyze ball-milled cellulose in a microwave reactor with total reducing sugar (TRS) yield of 25.3% under the best conditions at 190 °C for 3.5 h. It was cycled for at least seven times with high catalyst recovery rate (92.8%), acid density (0.63 mmol g-1) and magnetism (Ms = 12.9 Am2 kg-1), as well as high TRS yield (20.1%) from the hydrolysis of ball-milled cellulose. The catalyst was further successfully tested for the hydrolysis of tropical biomass with high TRS and glucose yields of 79.8% and 58.3% for bagasse, 47.2% and 35.6% for Jatropha hulls, as well as 54.4% and 35.8% for Plukenetia hulls.

  15. Rhodium(III)-Catalyzed Amidation of Unactivated C(sp(3) )-H Bonds.

    Science.gov (United States)

    Wang, He; Tang, Guodong; Li, Xingwei

    2015-10-26

    Nitrogenation by direct functionalization of C-H bonds represents an important strategy for constructing C-N bonds. Rhodium(III)-catalyzed direct amidation of unactivated C(sp(3) )-H bonds is rare, especially under mild reaction conditions. Herein, a broad scope of C(sp(3) )-H bonds are amidated under rhodium catalysis in high efficiency using 3-substituted 1,4,2-dioxazol-5-ones as the amide source. The protocol broadens the scope of rhodium(III)-catalyzed C(sp(3) )-H activation chemistry, and is applicable to the late-stage functionalization of natural products. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Beta-D-xylosidase from Selenomonas ruminantium: thermodynamics of enzyme-catalyzed and noncatalyzed reactions

    Science.gov (United States)

    Beta-D-xylosidase/alpha-L-arabinofuranosidase from Selenomonas ruminantium (SXA) is the most active enzyme known for catalyzing hydrolysis of 1,4-beta-D-xylooligosaccharides to D-xylose. Temperature dependence for hydrolysis of 4-nitrophenyl-beta-D-xylopyranoside (4NPX), 4-nitrophenyl-alpha-L-arabi...

  17. Formation and hydrolysis of amide bonds by lipase A from Candida antarctica; exceptional features.

    Science.gov (United States)

    Liljeblad, Arto; Kallio, Pauli; Vainio, Marita; Niemi, Jarmo; Kanerva, Liisa T

    2010-02-21

    Various commercial lyophilized and immobilized preparations of lipase A from Candida antarctica (CAL-A) were studied for their ability to catalyze the hydrolysis of amide bonds in N-acylated alpha-amino acids, 3-butanamidobutanoic acid (beta-amino acid) and its ethyl ester. The activity toward amide bonds is highly untypical of lipases, despite the close mechanistic analogy to amidases which normally catalyze the corresponding reactions. Most CAL-A preparations cleaved amide bonds of various substrates with high enantioselectivity, although high variations in substrate selectivity and catalytic rates were detected. The possible role of contaminant protein species on the hydrolytic activity toward these bonds was studied by fractionation and analysis of the commercial lyophilized preparation of CAL-A (Cat#ICR-112, Codexis). In addition to minor impurities, two equally abundant proteins were detected, migrating on SDS-PAGE a few kDa apart around the calculated size of CAL-A. Based on peptide fragment analysis and sequence comparison both bands shared substantial sequence coverage with CAL-A. However, peptides at the C-terminal end constituting a motile domain described as an active-site flap were not identified in the smaller fragment. Separated gel filtration fractions of the two forms of CAL-A both catalyzed the amide bond hydrolysis of ethyl 3-butanamidobutanoate as well as the N-acylation of methyl pipecolinate. Hydrolytic activity towards N-acetylmethionine was, however, solely confined to the fractions containing the truncated form of CAL-A. These fractions were also found to contain a trace enzyme impurity identified in sequence analysis as a serine carboxypeptidase. The possible role of catalytic impurities versus the function of CAL-A in amide bond hydrolysis is further discussed in the paper.

  18. Applications of Palladium-Catalyzed C-N Cross-Coupling Reactions.

    Science.gov (United States)

    Ruiz-Castillo, Paula; Buchwald, Stephen L

    2016-10-12

    Pd-catalyzed cross-coupling reactions that form C-N bonds have become useful methods to synthesize anilines and aniline derivatives, an important class of compounds throughout chemical research. A key factor in the widespread adoption of these methods has been the continued development of reliable and versatile catalysts that function under operationally simple, user-friendly conditions. This review provides an overview of Pd-catalyzed N-arylation reactions found in both basic and applied chemical research from 2008 to the present. Selected examples of C-N cross-coupling reactions between nine classes of nitrogen-based coupling partners and (pseudo)aryl halides are described for the synthesis of heterocycles, medicinally relevant compounds, natural products, organic materials, and catalysts.

  19. Gold-Catalyzed Formal C-C Bond Insertion Reaction of 2-Aryl-2-diazoesters with 1,3-Diketones.

    Science.gov (United States)

    Ren, Yuan-Yuan; Chen, Mo; Li, Ke; Zhu, Shou-Fei

    2018-06-29

    The transition-metal-catalyzed formal C-C bond insertion reaction of diazo compounds with monocarbonyl compounds is well established, but the related reaction of 1,3-diketones instead gives C-H bond insertion products. Herein, we report a protocol for a gold-catalyzed formal C-C bond insertion reaction of 2-aryl-2-diazoesters with 1,3-diketones, which provides efficient access to polycarbonyl compounds with an all-carbon quaternary center. The aryl ester moiety plays a crucial role in the unusual chemoselectivity, and the addition of a Brønsted acid to the reaction mixture improves the yield of the C-C bond insertion product. A reaction mechanism involving cyclopropanation of a gold carbenoid with an enolate and ring-opening of the resulting donor-acceptor-type cyclopropane intermediate is proposed. This mechanism differs from that of the traditional Lewis-acid-catalyzed C-C bond insertion reaction of diazo compounds with monocarbonyl compounds, which involves a rearrangement of a zwitterion intermediate as a key step. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Iron-Catalyzed C-O Bond Activation: Opportunity for Sustainable Catalysis.

    Science.gov (United States)

    Bisz, Elwira; Szostak, Michal

    2017-10-23

    Oxygen-based electrophiles have emerged as some of the most valuable cross-coupling partners in organic synthesis due to several major strategic and environmental benefits, such as abundance and potential to avoid toxic halide waste. In this context, iron-catalyzed C-O activation/cross-coupling holds particular promise to achieve sustainable catalytic protocols due to its natural abundance, inherent low toxicity, and excellent economic and ecological profile. Recently, tremendous progress has been achieved in the development of new methods for functional-group-tolerant iron-catalyzed cross-coupling reactions by selective C-O cleavage. These methods establish highly attractive alternatives to traditional cross-coupling reactions by using halides as electrophilic partners. In particular, new easily accessible oxygen-based electrophiles have emerged as substrates in iron-catalyzed cross-coupling reactions, which significantly broaden the scope of this catalysis platform. New mechanistic manifolds involving iron catalysis have been established; thus opening up vistas for the development of a wide range of unprecedented reactions. The synthetic potential of this sustainable mode of reactivity has been highlighted by the development of new strategies in the construction of complex motifs, including in target synthesis. The most recent advances in sustainable iron-catalyzed cross-coupling of C-O-based electrophiles are reviewed, with a focus on both mechanistic aspects and synthetic utility. It should be noted that this catalytic manifold provides access to motifs that are often not easily available by other methods, such as the assembly of stereodefined dienes or C(sp 2 )-C(sp 3 ) cross-couplings, thus emphasizing the synthetic importance of this mode of reactivity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Cytochrome c catalyzes the in vitro synthesis of arachidonoyl glycine

    International Nuclear Information System (INIS)

    McCue, Jeffrey M.; Driscoll, William J.; Mueller, Gregory P.

    2008-01-01

    Long chain fatty acyl glycines are an emerging class of biologically active molecules that occur naturally and produce a wide array of physiological effects. Their biosynthetic pathway, however, remains unknown. Here we report that cytochrome c catalyzes the synthesis of N-arachidonoyl glycine (NAGly) from arachidonoyl coenzyme A and glycine in the presence of hydrogen peroxide. The identity of the NAGly product was verified by isotope labeling and mass analysis. Other heme-containing proteins, hemoglobin and myoglobin, were considerably less effective in generating arachidonoyl glycine as compared to cytochrome c. The reaction catalyzed by cytochrome c in vitro points to its potential role in the formation of NAGly and other long chain fatty acyl glycines in vivo

  2. Modeling the mechanisms of biological GTP hydrolysis

    DEFF Research Database (Denmark)

    Carvalho, Alexandra T.P.; Szeler, Klaudia; Vavitsas, Konstantinos

    2015-01-01

    Enzymes that hydrolyze GTP are currently in the spotlight, due to their molecular switch mechanism that controls many cellular processes. One of the best-known classes of these enzymes are small GTPases such as members of the Ras superfamily, which catalyze the hydrolysis of the γ-phosphate bond...... in GTP. In addition, the availability of an increasing number of crystal structures of translational GTPases such as EF-Tu and EF-G have made it possible to probe the molecular details of GTP hydrolysis on the ribosome. However, despite a wealth of biochemical, structural and computational data, the way...

  3. Rhodium-catalyzed C-H functionalization with N-acylsaccharins.

    Science.gov (United States)

    Wu, Hongxiang; Liu, Tingting; Cui, Ming; Li, Yue; Jian, Junsheng; Wang, Hui; Zeng, Zhuo

    2017-01-18

    A rhodium-catalyzed C-H functionalization with activated amides by decarbonylation has been developed. Notably, this is the first C-H arylation employing N-acylsaccharins as coupling partners to give biaryls in good to excellent yields. The highlight of the work is the high tolerance of functional groups such as formyl, ester, and vinyl and the use of a removable directing group.

  4. Vinyl ether hydrolysis. VII. Isotope effects on catalysis by aqueous hydrofluoric acid

    International Nuclear Information System (INIS)

    Kresge, A.J.; Chen, H.J.; Chiang, Y.

    1977-01-01

    Comparison of rates of hydrolysis of three vinyl ethers catalyzed by HF in H 2 O and DF in D 2 O at 25 0 C gives primary isotope effects in the range k/sub H//k/sub D/ = 3.3 to 3.5. The unexpectedly small size of these effects may be attributed to strong, ω = 1325 to 1450 cm -1 , hydrogenic bending vibrations in the proton transfer transition states of these reactions along with the lack of compensatory bending vibrations in the diatomic proton donor

  5. Investigation of the complex reaction coordinate of acid catalyzed amide hydrolysis from molecular dynamics simulations

    International Nuclear Information System (INIS)

    Zahn, Dirk

    2004-01-01

    The rate-determining step of acid catalyzed peptide hydrolysis is the nucleophilic attack of a water molecule to the carbon atom of the amide group. Therein the addition of the hydroxyl group to the amide carbon atom involves the association of a water molecule transferring one of its protons to an adjacent water molecule. The protonation of the amide nitrogen atom follows as a separate reaction step. Since the nucleophilic attack involves the breaking and formation of several bonds, the underlying reaction coordinate is rather complex. We investigate this reaction step from path sampling Car-Parrinello molecular dynamics simulations. This approach does not require the predefinition of reaction coordinates and is thus particularly suited for investigating reaction mechanisms. From our simulations the most relevant components of the reaction coordinate are elaborated. Though the C···O distance of the oxygen atom of the water molecule performing the nucleophilic attack and the corresponding amide carbon atom is a descriptor of the reaction progress, a complete picture of the reaction coordinate must include all three molecules taking part in the reaction. Moreover, the proton transfer is found to depend on favorable solvent configurations. Thus, also the arrangement of non-reacting, i.e. solvent water molecules needs to be considered in the reaction coordinate

  6. Palladium-catalyzed aryl C-H olefination with unactivated, aliphatic alkenes.

    Science.gov (United States)

    Deb, Arghya; Bag, Sukdev; Kancherla, Rajesh; Maiti, Debabrata

    2014-10-01

    Palladium-catalyzed coupling between aryl halides and alkenes (Mizoroki-Heck reaction) is one of the most popular reactions for synthesizing complex organic molecules. The limited availability, problematic synthesis, and higher cost of aryl halide precursors (or their equivalents) have encouraged exploration of direct olefination of aryl carbon-hydrogen (C-H) bonds (Fujiwara-Moritani reaction). Despite significant progress, the restricted substrate scope, in particular noncompliance of unactivated aliphatic olefins, has discouraged the use of this greener alternative. Overcoming this serious limitation, we report here a palladium-catalyzed chelation-assisted ortho C-H bond olefination of phenylacetic acid derivatives with unactivated, aliphatic alkenes in good to excellent yields with high regio- and stereoselectivities. The versatility of this operationally simple method has been demonstrated through drug diversification and sequential C-H olefination for synthesizing divinylbenzene derivatives.

  7. Reversible formation of intermediates during H3O+-catalyzed hydrolysis of amides. Observation of substantial 18O exchange accompanying the hydrolysis of acetanilide and N-cyclohexylacetamide

    International Nuclear Information System (INIS)

    Slebocka-Tilk, H.; Brown, R.S.; Olekszyk, J.

    1987-01-01

    Careful mass spectrometric analysis of the 18 O content of ∼ 50% enriched acetanilide (2) and N-cyclohexylacetamide (3) recovered from acidic media during the course of hydrolysis reveals that both species suffer 18 O loss. The percent of 18 O exchange per t/sub 1/2/ of hydrolysis increases as [H 3 O + ] decreases. For 2 at 72 0 C the amount of exchange increases from 0.5 +/- 0.5% (per t/sub 1/2/) in 1 M HCl to 9.4 +/- 0.5% in glycine buffer, [H 3 O + ] = 0.003 M. For 3 at 100 0 C the exchange is 1.05 +/- 0.3% (per t/sub 1/2/) at 1 M HCl and 9.0 +/- 0.4% in 0.01 M HCl. When these data are used to compute k/sub ex/ (the exchange rate constant), it shows a first-order dependence on [H 3 O + ] followed by a plateau at high [H 3 O + ] for both 2 and 3

  8. Pd(II)-Catalyzed Enantioselective C-H Olefination of Diphenylacetic Acids

    Science.gov (United States)

    Shi, Bing-Feng; Zhang, Yang-Hui; Lam, Jonathan K.; Wang, Dong-Hui; Yu, Jin-Quan

    2009-01-01

    Pd(II)-catalyzed enantioselective C-H olefination of diphenylacetic acid substrates has been achieved through the use of mono-protected chiral amino acid ligands. The absolute configuration of the resulting olefinated products is consistent with that of a proposed C-H insertion intermediate. PMID:20017549

  9. Altered levels of acylcarnitines, phosphatidylcholines, and sphingomyelins in peritoneal fluid from ovarian endometriosis patients.

    Science.gov (United States)

    Vouk, Katja; Ribič-Pucelj, Martina; Adamski, Jerzy; Rižner, Tea Lanišnik

    2016-05-01

    Endometriosis is a complex, polygenic, and estrogen-dependent disease that affects 6% to 10% of women of reproductive age, and 30% to 50% of women with infertility and/or pelvic pain. Surgical diagnosis of endometriosis is still the gold standard, as there are currently no diagnostic biomarkers available. Due to the invasive diagnostics, it can take up to 11 years before affected women are diagnosed and receive the appropriate treatment. We performed a targeted metabolomics study to search for potential semi-invasive biomarkers in peritoneal fluid from endometriosis patients. Our case-control study comprised 29 ovarian endometriosis patients and 36 healthy control women. The 148 metabolites included acylcarnitines, glycerophospholipids, and sphingolipids, which were quantified by electrospray ionization tandem mass spectrometry. The strength of association between the metabolites and the metabolite ratios and disease was assessed using crude and adjusted odds ratios. The best combination of biomarkers was then selected by performing step-wise logistic regression. Our analysis reveals significantly decreased concentrations of 10 metabolites, of carnitine and acylcarnitines (C0, C8:1, C6C4:1 DC, C10:1), phosphatidylcholines (PC aa C38:3, PC aa C38:4, PC aa C40:4, PC aa C40:5), and sphingomyelins (SM C16:1, SM C18:1), and 125 significantly altered metabolite ratios in patients versus control women. The best model includes two ratios: a carnitine to a phosphatidylcholine (C0/PC ae C36:0); and between two phosphatidylcholines (PC aa C30:0/PC ae C32:2). When adjusted for age, this provides sensitivity of 82.8% and specificity of 94.4%, with AUC of 0.944. Our study supports the importance of carnitine, phosphatidylcholine, and sphingomyelin metabolites in the pathophysiology of endometriosis, and confirms the potential for the combination of individual metabolite ratios to provide biomarkers for semi-invasive diagnostics. Copyright © 2016 Elsevier Ltd. All rights

  10. Synthesis and spectral characterization of 2,2-diphenylethyl glucosinolate and HPLC-based reaction progress curve data for the enzymatic hydrolysis of glucosinolates by Sinapis alba myrosinase

    Directory of Open Access Journals (Sweden)

    Chase A. Klingaman

    2017-02-01

    Full Text Available The data presented in this article are related to the research article, “HPLC-based enzyme kinetics assay for glucosinolate hydrolysis facilitate analysis of systems with both multiple reaction products and thermal enzyme denaturation” (C.K. Klingaman, M.J. Wagner, J.R. Brown, J.B. Klecker, E.H. Pauley, C.J. Noldner, J.R. Mays, [1]. This data article describes (1 the synthesis and spectral characterization data of a non-natural glucosinolate analogue, 2,2-diphenylethyl glucosinolate, (2 HPLC standardization data for glucosinolate, isothiocyanate, nitrile, and amine analytes, (3 reaction progress curve data for enzymatic hydrolysis reactions with variable substrate concentration, enzyme concentration, buffer pH, and temperature, and (4 normalized initial velocities of hydrolysis/formation for analytes. These data provide a comprehensive description of the enzyme-catalyzed hydrolysis of 2,2-diphenylethyl glucosinolate (5 and glucotropaeolin (6 under widely varied conditions.

  11. Nitrile-specifier Proteins Involved in Glucosinolate Hydrolysis in Arabidopsis thaliana*S⃞

    Science.gov (United States)

    Kissen, Ralph; Bones, Atle M.

    2009-01-01

    Glucosinolates are plant secondary metabolites present in Brassicaceae plants such as the model plant Arabidopsis thaliana. Intact glucosinolates are believed to be biologically inactive, whereas degradation products after hydrolysis have multiple roles in growth regulation and defense. The degradation of glucosinolates is catalyzed by thioglucosidases called myrosinases and leads by default to the formation of isothiocyanates. The interaction of a protein called epithiospecifier protein (ESP) with myrosinase diverts the reaction toward the production of epithionitriles or nitriles depending on the glucosinolate structure. Here we report the identification of a new group of nitrile-specifier proteins (AtNSPs) in A. thaliana able to generate nitriles in conjunction with myrosinase and a more detailed characterization of one member (AtNSP2). Recombinant AtNSP2 expressed in Escherichia coli was used to test its impact on the outcome of glucosinolate hydrolysis using a gas chromatography-mass spectrometry approach. AtNSP proteins share 30–45% sequence homology with A. thaliana ESP. Although AtESP and AtNSP proteins can switch myrosinase-catalyzed degradation of 2-propenylglucosinolate from isothiocyanate to nitrile, only AtESP generates the corresponding epithionitrile. Using the aromatic benzylglucosinolate, recombinant AtNSP2 is also able to direct product formation to the nitrile. Analysis of glucosinolate hydrolysis profiles of transgenic A. thaliana plants overexpressing AtNSP2 confirms its nitrile-specifier activity in planta. In silico expression analysis reveals distinctive expression patterns of AtNSPs, which supports a biological role for these proteins. In conclusion, we show that AtNSPs belonging to a new family of A. thaliana proteins structurally related to AtESP divert product formation from myrosinase-catalyzed glucosinolate hydrolysis and, thereby, likely affect the biological consequences of glucosinolate degradation. We discuss similarities and

  12. Effects of brefeldin A on sphingomyelin transport and lipid synthesis in BHK21 cells.

    OpenAIRE

    Kallen, K J; Quinn, P; Allan, D

    1993-01-01

    1. Addition of brefeldin A (BFA) to BHK cells incubated for 4 h with [3H]acetate led to a 3-4-fold increase in incorporation of label into sphingomyelin, monoglucosylceramide and cholesterol ester compared with untreated controls. There was a similar increase in incorporation of [3H]choline into sphingomyelin. The level of cholesterol ester increased 3-fold when BFA was added to cells labelled to equilibrium with [3H]acetate, but no statistically significant changes in the levels of other lip...

  13. Raft-based sphingomyelin interactions revealed by new fluorescent sphingomyelin analogs

    Science.gov (United States)

    Kinoshita, Masanao; Suzuki, Kenichi G.N.; Takada, Misa; Ano, Hikaru; Abe, Mitsuhiro; Makino, Asami; Kobayashi, Toshihide; Hirosawa, Koichiro M.; Fujiwara, Takahiro K.; Murata, Michio

    2017-01-01

    Sphingomyelin (SM) has been proposed to form cholesterol-dependent raft domains and sphingolipid domains in the plasma membrane (PM). How SM contributes to the formation and function of these domains remains unknown, primarily because of the scarcity of suitable fluorescent SM analogs. We developed new fluorescent SM analogs by conjugating a hydrophilic fluorophore to the SM choline headgroup without eliminating its positive charge, via a hydrophilic nonaethylene glycol linker. The new analogs behaved similarly to the native SM in terms of their partitioning behaviors in artificial liquid order-disorder phase-separated membranes and detergent-resistant PM preparations. Single fluorescent molecule tracking in the live-cell PM revealed that they indirectly interact with each other in cholesterol- and sphingosine backbone–dependent manners, and that, for ∼10–50 ms, they undergo transient colocalization-codiffusion with a glycosylphosphatidylinositol (GPI)-anchored protein, CD59 (in monomers, transient-dimer rafts, and clusters), in CD59-oligomer size–, cholesterol-, and GPI anchoring–dependent manners. These results suggest that SM continually and rapidly exchanges between CD59-associated raft domains and the bulk PM. PMID:28330937

  14. Microwave-assisted Weak Acid Hydrolysis of Proteins

    Directory of Open Access Journals (Sweden)

    Miyeong Seo

    2012-06-01

    Full Text Available Myoglobin was hydrolyzed by microwave-assisted weak acid hydrolysis with 2% formic acid at 37 oC, 50 oC, and100 oC for 1 h. The most effective hydrolysis was observed at 100 oC. Hydrolysis products were investigated using matrixassistedlaser desorption/ionization time-of-flight mass spectrometry. Most cleavages predominantly occurred at the C-termini ofaspartyl residues. For comparison, weak acid hydrolysis was also performed in boiling water for 20, 40, 60, and 120 min. A 60-min weak acid hydrolysis in boiling water yielded similar results as a 60-min microwave-assisted weak acid hydrolysis at100 oC. These results strongly suggest that microwave irradiation has no notable enhancement effect on acid hydrolysis of proteinsand that temperature is the major factor that determines the effectiveness of weak acid hydrolysis.

  15. Gas phase hydrolysis of formaldehyde to form methanediol: impact of formic acid catalysis.

    Science.gov (United States)

    Hazra, Montu K; Francisco, Joseph S; Sinha, Amitabha

    2013-11-21

    We find that formic acid (FA) is very effective at facilitating diol formation through its ability to reduce the barrier for the formaldehyde (HCHO) hydrolysis reaction. The rate limiting step in the mechanism involves the isomerization of a prereactive collision complex formed through either the HCHO···H2O + FA and/or HCHO + FA···H2O pathways. The present study finds that the effective barrier height, defined as the difference between the zero-point vibrational energy (ZPE) corrected energy of the transition state (TS) and the HCHO···H2O + FA and HCHO + FA···H2O starting reagents, are respectively only ∼1 and ∼4 kcal/mol. These barriers are substantially lower than the ∼17 kcal/mol barrier associated with the corresponding step in the hydrolysis of HCHO catalyzed by a single water molecule (HCHO + H2O + H2O). The significantly lower barrier heights for the formic acid catalyzed pathway reveal a new important role that organic acids play in the gas phase hydrolysis of atmospheric carbonyl compounds.

  16. Low frequency ultrasonic-assisted hydrolysis of starch in the presence of α-amylase.

    Science.gov (United States)

    Gaquere-Parker, Anne; Taylor, Tamera; Hutson, Raihannah; Rizzo, Ashley; Folds, Aubrey; Crittenden, Shastina; Zahoor, Neelam; Hussein, Bilal; Arruda, Aaron

    2018-03-01

    Hydrolysis of starch is an important process in the food industry and in the production of bioethanol or smaller carbohydrate molecules that can be used as starting blocks for chemical synthesis. Such hydrolysis can be enhanced by lowering the pH, heating the reaction mixture or catalyzing the reaction with enzymes. This study reports the effect of sonication on the reaction rate of starch hydrolysis at different temperatures, in the presence or absence of alpha-amylase. Starch Azure, a commercially available potato starch covalently linked with Remazol Brilliant Blue, has been chosen since its hydrolysis releases a blue dye, which concentration can be monitored by UV Vis spectroscopy. Ultrasounds, regardless of experimental conditions, provide the highest reaction rate for such hydrolysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Cardiovascular effects of sphingosine-1-phosphate and other sphingomyelin metabolites

    NARCIS (Netherlands)

    Alewijnse, Astrid E.; Peters, Stephan L. M.; Michel, Martin C.

    2004-01-01

    1 Upon various stimuli, cells metabolize sphingomyelin from the cellular plasma membrane to form sphingosylphosphorylcholine (SPC) or ceramide. The latter can be further metabolized to sphingosine and then sphingosine-1-phosphate (S1P). Apart from local formation, S1P and SPC are major constituents

  18. Sphingomyelin Synthase 1 Is Essential for Male Fertility in Mice.

    Directory of Open Access Journals (Sweden)

    Anke Wittmann

    Full Text Available Sphingolipids and the derived gangliosides have critical functions in spermatogenesis, thus mutations in genes involved in sphingolipid biogenesis are often associated with male infertility. We have generated a transgenic mouse line carrying an insertion in the sphingomyelin synthase gene Sms1, the enzyme which generates sphingomyelin species in the Golgi apparatus. We describe the spermatogenesis defect of Sms1-/- mice, which is characterized by sloughing of spermatocytes and spermatids, causing progressive infertility of male homozygotes. Lipid profiling revealed a reduction in several long chain unsaturated phosphatidylcholins, lysophosphatidylcholins and sphingolipids in the testes of mutants. Multi-Spectral Optoacoustic Tomography indicated blood-testis barrier dysfunction. A supplementary diet of the essential omega-3 docosahexaenoic acid and eicosapentaenoic acid diminished germ cell sloughing from the seminiferous epithelium and restored spermatogenesis and fertility in 50% of previously infertile mutants. Our findings indicate that SMS1 has a wider than anticipated role in testis polyunsaturated fatty acid homeostasis and for male fertility.

  19. Iridium/Bipyridine-Catalyzed ortho-Selective C-H Borylation of Phenol and Aniline Derivatives.

    Science.gov (United States)

    Li, Hong-Liang; Kanai, Motomu; Kuninobu, Yoichiro

    2017-11-03

    An iridium-catalyzed ortho-selective C-H borylation of phenol and aniline derivatives has been successfully developed. Iridium/bipyridine-catalyzed C-H borylation generally occurred at the meta- and para-positions of aromatic substrates. Introduction of an electron-withdrawing substituent on the bipyridine-type ligand and a methylthiomethyl group on the hydroxy and amino groups of the phenol and aniline substrates, however, dramatically altered the regioselectivity, affording exclusively ortho-borylated products. The reaction proceeded in good to excellent yields with good functional group tolerance. C-H borylation was applied to the synthesis of a calcium receptor modulator.

  20. Borane-catalyzed cracking of C-C bonds in coal; Boran-katalysierte C-C-Bindungungsspaltung in Steinkohle

    Energy Technology Data Exchange (ETDEWEB)

    Narangerel, J; Haenel, M W [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany)

    1998-09-01

    Coal, especially coking coal, was reacted with hydrogen at comparatively mild reaction conditions (150-280 degrees centigrade, 20 MPa hydrogen pressure) in the presence of catalysts consisting of borange reagents and certain transition metal halides to obtaine more than 80 percent of pyridine-soluble products. The influence of the degree of coalification, catalyst and temperature on the borane-catalyzed hydrogenolysis of C-C bonds in coal was investigated. (orig.) [Deutsch] Steinkohlen, insbesondere im Inkohlungsbereich der Fettkohlen (Kokskohlen), werden in Gegenwart von Katalysatoren aus Boran-Reagentien und bestimmten Uebergangsmetallhalogeniden mit Wasserstoff bei vergleichsweise milden Reaktionsbedingungen (250-280 C, 20 MPa Wasserstoffdruck) in zu ueber 80% pyridinloesliche Produkte umgewandelt. Der Einfluss von Inkohlungsgrad, Katalysator und Temperatur auf die Boran-katalysierte C-C-Bindungshydrogenolyse in Kohle wurde untersucht. (orig.)

  1. Mild and Efficient Nickel-Catalyzed Heck Reactions with Electron-Rich Olefins

    DEFF Research Database (Denmark)

    Gøgsig, Thomas; Kleimark, Jonatan; Lill, Sten O. Nilsson

    2012-01-01

    proved compatible, and the corresponding aryl methyl ketone could be secured after hydrolysis in yields approaching quantitative. Good functional group tolerance was observed matching the characteristics of the analogous Pd-catalyzed Heck reaction. The high levels of catalytic activity were explained...

  2. Efficient asymmetric hydrolysis of styrene oxide catalyzed by Mung bean epoxide hydrolases in ionic liquid-based biphasic systems.

    Science.gov (United States)

    Chen, Wen-Jing; Lou, Wen-Yong; Zong, Min-Hua

    2012-07-01

    The asymmetric hydrolysis of styrene oxide to (R)-1-phenyl-1,2-ethanediol using Mung bean epoxide hydrolases was, for the first time, successfully conducted in an ionic liquid (IL)-containing biphasic system. Compared to aqueous monophasic system, IL-based biphasic systems could not only dissolve the substrate, but also effectively inhibit the non-enzymatic hydrolysis, and therefore markedly improve the reaction efficiency. Of all the tested ILs, the best results were observed in the biphasic system containing C(4)MIM·PF(6), which exhibited good biocompatibility with the enzyme and was an excellent solvent for the substrate. In the C(4)MIM·PF(6)/buffer biphasic system, it was found that the optimal volume ratio of IL to buffer, reaction temperature, buffer pH and substrate concentration were 1/6, 35°C, 6.5 and 100 mM, respectively, under which the initial reaction rate, the yield and the product e.e. were 18.4 mM/h, 49.4% and 97.0%. The biocatalytic process was shown to be feasible on a 500-mL preparative scale. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Development of a mathematical model describing hydrolysis and co-fermentation of C6 and C5 sugars

    DEFF Research Database (Denmark)

    Morales Rodriguez, Ricardo; Gernaey, Krist; Meyer, Anne S.

    2010-01-01

    saccharification and co-fermentation (SSCF) of C6 and C5 sugars. Model construction has been carried out by combining existing mathematical models for enzymatic hydrolysis on the one hand and co-fermentation on the other hand. An inhibition of ethanol on cellulose conversion was introduced in order to increase...

  4. Cu(II)-catalyzed esterification reaction via aerobic oxidative cleavage of C(CO)-C(alkyl) bonds.

    Science.gov (United States)

    Ma, Ran; He, Liang-Nian; Liu, An-Hua; Song, Qing-Wen

    2016-02-04

    A novel Cu(II)-catalyzed aerobic oxidative esterification of simple ketones for the synthesis of esters has been developed with wide functional group tolerance. This process is assumed to go through a tandem sequence consisting of α-oxygenation/esterification/nucleophilic addition/C-C bond cleavage and carbon dioxide is released as the only byproduct.

  5. Calcium-dependent hydrolysis of supported planar lipids was triggered by honey bee venom phospholipase A2 with the right orientation at the interface.

    Science.gov (United States)

    Kai, Siqi; Li, Xu; Li, Bolin; Han, Xiaofeng; Lu, Xiaolin

    2017-12-20

    Hydrolysis of planar phospholipids catalyzed by honey bee venom phospholipase A 2 (bvPLA 2 ) was studied. Experiments demonstrated that Ca 2+ ions mediated between the lipids and bvPLA 2 , induced reorientation of bvPLA 2 , and activated hydrolysis. One of the hydrolysis products, fatty acids, was desorbed, and the other one, lysophospholipids, self-organized at the interface.

  6. Selective ultrasound-enhanced enzymatic hydrolysis of oleuropein to its aglycon in olive (Olea europaea L.) leaf extracts.

    Science.gov (United States)

    Delgado-Povedano, María Del Mar; Priego-Capote, Feliciano; Luque de Castro, María Dolores

    2017-04-01

    Hydrolysis of oleuropein, the main phenol in olive (Olea europaea L.) leaf extracts, to oleuropein aglycon and other subsequent products in the hydrolytic pathway can be catalyzed by different enzymes. Three of the most used hydrolases were assayed to catalyze the process, and β-glucosidase from Aspergillus niger was selected. Acceleration of the enzymatic hydrolysis by ultrasound (US) was studied using a Box-Behnken design (duty cycle, amplitude, cycle time) and an oleuropein standard, and the optimum US conditions for achieving maximum yield of oleuropein aglycon were 0.5s/s duty cycle, 50% amplitude and 45s cycle. The method was applied to obtain oleuropein aglycon from commercial and laboratory extracts from olive leaves, which may have a pharmacological use as deduced by its healthy properties. The kinetics of the US-assisted enzymatic hydrolysis was monitored by analysis of the target compounds using liquid chromatography-tandem mass spectrometry. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Manganese-Catalyzed Aminomethylation of Aromatic Compounds with Methanol as a Sustainable C1 Building Block.

    Science.gov (United States)

    Mastalir, Matthias; Pittenauer, Ernst; Allmaier, Günter; Kirchner, Karl

    2017-07-05

    This study represents the first example of a manganese-catalyzed environmentally benign, practical three-component aminomethylation of activated aromatic compounds including naphtols, phenols, pyridines, indoles, carbazoles, and thiophenes in combination with amines and MeOH as a C1 source. These reactions proceed with high atom efficiency via a sequence of dehydrogenation and condensation steps which give rise to selective C-C and C-N bond formations, thereby releasing hydrogen and water. A well-defined hydride Mn(I) PNP pincer complex, recently developed in our laboratory, catalyzes this process in a very efficient way, and a total of 28 different aminomethylated products were synthesized and isolated yields of up to 91%. In a preliminary study, a related Fe(II) PNP pincer complex was shown to catalyze the methylation of 2-naphtol rather than its aminomethylation displaying again the divergent behavior of isoelectronic Mn(I) and Fe(II) PNP pincer systems.

  8. Palladium catalyzed selective distal C-H olefination of biaryl systems.

    Science.gov (United States)

    Maity, Soham; Hoque, Ehtasimul; Dhawa, Uttam; Maiti, Debabrata

    2016-11-29

    Palladium catalyzed selective distal C-H activation with nitrile based templates has been of significant research interest in recent times. In this report, we disclose the distal C-H olefination of biphenyl systems with high regio- and stereo-selectivity and useful synthetic yields. The utility of this method has been demonstrated through its wide olefin scope, its operation at the gram scale and the easy removal/recovery of the directing group.

  9. pH catalyzed pretreatment of corn bran for enhanced enzymatic arabinoxylan degradation

    DEFF Research Database (Denmark)

    Agger, Jane; Johansen, Katja Salomon; Meyer, Anne S.

    2011-01-01

    Corn bran is mainly made up of the pericarp of corn kernels and is a byproduct stream resulting from the wet milling step in corn starch processing. Through statistic modeling this study examined the optimization of pretreatment of corn bran for enzymatic hydrolysis. A low pH pretreatment (pH 2......, 150°C, 65min) boosted the enzymatic release of xylose and glucose and maximized biomass solubilization. With more acidic pretreatment followed by enzymatic hydrolysis the total xylose release was maximized (at pH 1.3) reaching ∼50% by weight of the original amount present in destarched corn bran......, but the enzyme catalyzed xylose release was maximal after pretreatment at approx. pH 2. The total glucose release peaked after pretreatment of approx. pH 1.5 with an enzymatic release of approx. 68% by weight of the original amounts present in destarched corn bran. For arabinose the enzymatic release...

  10. Copper-catalyzed transformation of ketones to amides via C(CO)-C(alkyl) bond cleavage directed by picolinamide.

    Science.gov (United States)

    Ma, Haojie; Zhou, Xiaoqiang; Zhan, Zhenzhen; Wei, Daidong; Shi, Chong; Liu, Xingxing; Huang, Guosheng

    2017-09-13

    Copper catalyzed chemoselective cleavage of the C(CO)-C(alkyl) bond leading to C-N bond formation with chelation assistance of N-containing directing groups is described. Inexpensive Cu(ii)-acetate serves as a convenient catalyst for this transformation. This method highlights the emerging strategy to transform unactivated alkyl ketones into amides in organic synthesis and provides a new strategy for C-C bond cleavage.

  11. Rhodium(III)- and iridium(III)-catalyzed C7 alkylation of indolines with diazo compounds.

    Science.gov (United States)

    Ai, Wen; Yang, Xueyan; Wu, Yunxiang; Wang, Xuan; Li, Yuanchao; Yang, Yaxi; Zhou, Bing

    2014-12-22

    A Rh(III)-catalyzed procedure for the C7-selective C-H alkylation of various indolines with α-diazo compounds at room temperature is reported. The advantages of this process are: 1) simple, mild, and pH-neutral reaction conditions, 2) broad substrate scope, 3) complete regioselectivity, 4) no need for an external oxidant, and 5) N2 as the sole byproduct. Furthermore, alkylation and bis-alkylation of carbazoles at the C1 and C8 positions have also been developed. More significantly, for the first time, a successful Ir(III)-catalyzed intermolecular insertion of arene C-H bonds into α-diazo compounds is reported. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Hydrolysis and formation constants at 250C

    International Nuclear Information System (INIS)

    Phillips, S.L.

    1982-05-01

    A database consisting of hydrolysis and formation constants for about 20 metals associated with the disposal of nuclear waste is given. Complexing ligands for the various ionic species of these metals include OH, F, Cl, SO 4 , PO 4 and CO 3 . Table 1 consists of tabulated calculated and experimental values of log K/sub xy/, mainly at 25 0 C and various ionic strengths together with references to the origin of the data. Table 2 consists of a column of recommended stability constants at 25 0 C and zero ionic strength tabulated in the column headed log K/sub xy/(0); other columns contain coefficients for an extended Debye-Huckel equation to permit calculations of stability constants up to 3 ionic strength, and up to 0.7 ionic strength using the Davies equation. Selected stability constants calculated with these coefficients for various ionic strengths agree to an average of +- 2% when compared with published experimental and calculated values

  13. Behavior of sphingomyelin and ceramide in a tear film lipid layer model

    Czech Academy of Sciences Publication Activity Database

    Olžyńska, A.; Cwiklik, Lukasz

    2017-01-01

    Roč. 210, March (2017), s. 128-134 ISSN 0940-9602 Institutional support: RVO:61388963 Keywords : tear film lipid layer * molecular dynamics simulations * Langmuir balance * sphingomyelin * ceramide Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.864, year: 2016

  14. Switching catalysis from hydrolysis to perhydrolysis in P. fluorescens esterase

    Science.gov (United States)

    Yin, De Lu (Tyler); Bernhardt, Peter; Morley, Krista L.; Jiang, Yun; Cheeseman, Jeremy D.; Purpero, Vincent; Schrag, Joseph D.; Kazlauskas, Romas J.

    2010-01-01

    Many serine hydrolases catalyze perhydrolysis – the reversible formation of per-acids from carboxylic acids and hydrogen peroxide. Recently we showed that a single amino acid substitution in the alcohol binding pocket - L29P - in Pseudomonas fluorescens (SIK WI) aryl esterase (PFE) increased the specificity constant of PFE for peracetic acid formation >100-fold [Bernhardt et al. Angew. Chem. Intl. Ed. 2005, 44, 2742]. In this paper, we extend this work to address the three following questions. First, what is the molecular basis of the increase in perhydrolysis activity? We previously proposed that the L29P substitution creates a hydrogen bond between the enzyme and hydrogen peroxide in the transition state. Here we report two x-ray structures of L29P PFE that support this proposal. Both structures show a main chain carbonyl oxygen closer to the active-site serine as expected. One structure further shows acetate in the active site in an orientation consistent with reaction by an acyl-enzyme mechanism. We also detected an acyl-enzyme intermediate in the hydrolysis of ε-caprolactone by mass spectrometry. Second, can we further increase perhydrolysis activity? We discovered that the reverse reaction – hydrolysis of peracetic acid to acetic acid and hydrogen peroxide – occurs at nearly the diffusion limited rate. Since the reverse reaction cannot increase further, neither can the forward reaction. Consistent with this prediction, two variants with additional amino acid substitutions showed two fold higher kcat, but Km also increased so the specificity constant, kcat/Km, remained similar. Third, how does the L29P substitution change the esterase activity? Ester hydrolysis decreased for most esters (75-fold for ethyl acetate), but not for methyl esters. In contrast, L29P PFE catalyzed hydrolysis of ε-caprolactone five times more efficiently than wild-type PFE. Molecular modeling suggests that moving the carbonyl group closer to the active site blocks access for

  15. Switching Catalysis from Hydrolysis to Perhydrolysis in Pseudomonas fluorescens Esterase

    Energy Technology Data Exchange (ETDEWEB)

    Yin, D.; Bernhardt, P; Morley, K; Jiang, Y; Cheeseman, J; Purpero, V; Schrag, J; Kazlauskas, R

    2010-01-01

    Many serine hydrolases catalyze perhydrolysis, the reversible formation of peracids from carboxylic acids and hydrogen peroxide. Recently, we showed that a single amino acid substitution in the alcohol binding pocket, L29P, in Pseudomonas fluorescens (SIK WI) aryl esterase (PFE) increased the specificity constant of PFE for peracetic acid formation >100-fold [Bernhardt et al. (2005) Angew. Chem., Int. Ed. 44, 2742]. In this paper, we extend this work to address the three following questions. First, what is the molecular basis of the increase in perhydrolysis activity? We previously proposed that the L29P substitution creates a hydrogen bond between the enzyme and hydrogen peroxide in the transition state. Here we report two X-ray structures of L29P PFE that support this proposal. Both structures show a main chain carbonyl oxygen closer to the active site serine as expected. One structure further shows acetate in the active site in an orientation consistent with reaction by an acyl-enzyme mechanism. We also detected an acyl-enzyme intermediate in the hydrolysis of {var_epsilon}-caprolactone by mass spectrometry. Second, can we further increase perhydrolysis activity? We discovered that the reverse reaction, hydrolysis of peracetic acid to acetic acid and hydrogen peroxide, occurs at nearly the diffusion limited rate. Since the reverse reaction cannot increase further, neither can the forward reaction. Consistent with this prediction, two variants with additional amino acid substitutions showed 2-fold higher k{sub cat}, but K{sub m} also increased so the specificity constant, k{sub cat}/K{sub m}, remained similar. Third, how does the L29P substitution change the esterase activity? Ester hydrolysis decreased for most esters (75-fold for ethyl acetate) but not for methyl esters. In contrast, L29P PFE catalyzed hydrolysis of {var_epsilon}-caprolactone five times more efficiently than wild-type PFE. Molecular modeling suggests that moving the carbonyl group closer to the

  16. Coal liquefaction by base-catalyzed hydrolysis with CO.sub.2 capture

    Science.gov (United States)

    Xiao, Xin

    2014-03-18

    The one-step hydrolysis of diverse biomaterials including coal, cellulose materials such as lumber and forestry waste, non-food crop waste, lignin, vegetable oils, animal fats and other source materials used for biofuels under mild processing conditions which results in the formation of a liquid fuel product along with the recovery of a high purity CO.sub.2 product is provided.

  17. Sphingomyelin synthases regulate protein trafficking and secretion.

    Directory of Open Access Journals (Sweden)

    Marimuthu Subathra

    Full Text Available Sphingomyelin synthases (SMS1 and 2 represent a class of enzymes that transfer a phosphocholine moiety from phosphatidylcholine onto ceramide thus producing sphingomyelin and diacylglycerol (DAG. SMS1 localizes at the Golgi while SMS2 localizes both at the Golgi and the plasma membrane. Previous studies from our laboratory showed that modulation of SMS1 and, to a lesser extent, of SMS2 affected the formation of DAG at the Golgi apparatus. As a consequence, down-regulation of SMS1 and SMS2 reduced the localization of the DAG-binding protein, protein kinase D (PKD, to the Golgi. Since PKD recruitment to the Golgi has been implicated in cellular secretion through the trans golgi network (TGN, the effect of down-regulation of SMSs on TGN-to-plasma membrane trafficking was studied. Down regulation of either SMS1 or SMS2 significantly retarded trafficking of the reporter protein vesicular stomatitis virus G protein tagged with GFP (VSVG-GFP from the TGN to the cell surface. Inhibition of SMSs also induced tubular protrusions from the trans Golgi network reminiscent of inhibited TGN membrane fission. Since a recent study demonstrated the requirement of PKD activity for insulin secretion in beta cells, we tested the function of SMS in this model. Inhibition of SMS significantly reduced insulin secretion in rat INS-1 cells. Taken together these results provide the first direct evidence that both enzymes (SMS1 and 2 are capable of regulating TGN-mediated protein trafficking and secretion, functions that are compatible with PKD being a down-stream target for SMSs in the Golgi.

  18. Selectivity control in pd-catalyzed c-h functionalization reactions

    OpenAIRE

    Flores Gaspar, Areli

    2013-01-01

    Benzocyclobutenones are an intriguing four-membered ring ketone. In the present thesis, we have developed a new protocol for selectively preparing benzocyclobutenones through intramolecular acylation of aryl bromides via palladium catalyzed C-H bond functionalization reactions based on rac-BINAP ligand. We also found that a subtle modification on the ligand backbone lead to a new catalytic manifold for preparing configurationally-pure styrene derivatives, when using dcpp (bis-dicyclohexylphos...

  19. Cellulose pretreatment with 1-n-butyl-3-methylimidazolium chloride for solid acid-catalyzed hydrolysis.

    Science.gov (United States)

    Kim, Soo-Jin; Dwiatmoko, Adid Adep; Choi, Jae Wook; Suh, Young-Woong; Suh, Dong Jin; Oh, Moonhyun

    2010-11-01

    This study has been focused on developing a cellulose pretreatment process using 1-n-butyl-3-methylimidazolium chloride ([bmim]Cl) for subsequent hydrolysis over Nafion(R) NR50. Thus, several pretreatment variables such as the pretreatment period and temperature, and the [bmim]Cl amount were varied. Additionally, the [bmim]Cl-treated cellulose samples were characterized by X-ray diffraction analysis, and their crystallinity index values including CI(XD), CI(XD-CI) and CI(XD-CII) were then calculated. When correlated with these values, the concentrations of total reducing sugars (TRS) obtained by the pretreatment of native cellulose (NC) and glucose produced by the hydrolysis reaction were found to show a distinct relationship with the [CI(NC)-CI(XD)] and CI(XD-CII) values, respectively. Consequently, the cellulose pretreatment step with [bmim]Cl is to loosen a crystalline cellulose through partial transformation of cellulose I to cellulose II and, furthermore, the TRS release, while the subsequent hydrolysis of [bmim]Cl-treated cellulose over Nafion(R) NR50 is effective to convert cellulose II to glucose. Copyright 2010 Elsevier Ltd. All rights reserved.

  20. Palladium-Catalyzed Enantioselective C-H Olefination of Diaryl Sulfoxides through Parallel Kinetic Resolution and Desymmetrization.

    Science.gov (United States)

    Zhu, Yu-Chao; Li, Yan; Zhang, Bo-Chao; Zhang, Feng-Xu; Yang, Yi-Nuo; Wang, Xi-Sheng

    2018-03-07

    The first example of Pd II -catalyzed enantioselective C-H olefination with non-chiral or racemic sulfoxides as directing groups was developed. A variety of chiral diaryl sulfoxides were synthesized with high enantioselectivity (up to 99 %) through both desymmetrization and parallel kinetic resolution (PKR). This is the first report of Pd II -catalyzed enantioselective C(sp 2 )-H functionalization through PKR, and it represents a novel strategy to construct sulfur chiral centers. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Enzymatic Hydrolysis of Pretreated Fibre Pressed Oil Palm Frond by using Sacchariseb C6

    Science.gov (United States)

    Hashim, F. S.; Yussof, H. W.; Zahari, M. A. K. M.; Rahman, R. A.; Illias, R. M.

    2017-06-01

    Enzymatic hydrolysis becomes a prominent technology for conversion of cellulosic biomass to its glucose monomers that requires an action of cellulolytic enzymes in a sequential and synergistic manner. In this study, the effect of agitation speed, glucan loading, enzyme loading, temperature and reaction time on the production of glucose from fibre pressed oil palm frond (FPOPF) during enzymatic hydrolysis was screened by a half factorial design 25-1 using Response Surface Methodology (RSM). The FPOPF sample was first delignified by alkaline pretreatment at 4.42 (w/v) sodium hydroxide for an hour prior to enzymatic hydrolysis using commercial cellulase enzyme, Sacchariseb C6. The effect of enzymatic hydrolysis on the structural of FPOPF has been evaluated by Scanning Electron Microscopy (SEM) analysis. Characterization of raw FPOPF comprised of 4.5 extractives, 40.7 glucan, 26.1 xylan, 26.2 lignin and 1.8 ash, whereas for pretreated FPOPF gave 0.3 extractives, 61.4 glucan, 20.4 xylan, 13.3 lignin and 1.3 ash. From this study, it was found that the best enzymatic hydrolysis condition yielded 33.01 ± 0.73 g/L of glucose when performed at 200 rpm of agitation speed, 60 FPU/mL of enzyme loading, 4 (w/w) of glucan loading, temperature at 55 □ and 72 hours of reaction time. The model obtained was significant with p-value enzymatic hydrolysis from pretreated FPOPF produce high amount of glucose that enhances it potential for industrial application. This glucose can be further used to produce high-value products.

  2. General synthesis of C-glycosyl amino acids via proline-catalyzed direct electrophilic alpha-amination of C-glycosylalkyl aldehydes.

    Science.gov (United States)

    Nuzzi, Andrea; Massi, Alessandro; Dondoni, Alessandro

    2008-10-16

    Non-natural axially and equatorially linked C-glycosyl alpha-amino acids (glycines, alanines, and CH2-serine isosteres) with either S or R alpha-configuration were prepared by D- and L-proline-catalyzed (de >95%) alpha-amination of C-glycosylalkyl aldehydes using dibenzyl azodicarboxylate as the electrophilic reagent.

  3. S,O-Ligand-Promoted Palladium-Catalyzed C-H Functionalization Reactions of Nondirected Arenes

    NARCIS (Netherlands)

    Naksomboon, K.; Valderas, C.; Gomez-Martinez, M.; Alvarez-Casao, Y.; Fernández Ibáñez, M.A.

    Pd(II)-catalyzed C-H functionalization of non directed arenes has been realized using an inexpensive and easily accessible type of bidentate S,O-ligand. The catalytic system shows high efficiency in the C-H olefination reaction of electron-rich and electron-poor arenes. This methodology is

  4. Cobalt-catalyzed C-H olefination of aromatics with unactivated alkenes.

    Science.gov (United States)

    Manoharan, Ramasamy; Sivakumar, Ganesan; Jeganmohan, Masilamani

    2016-08-18

    A cobalt-catalyzed C-H olefination of aromatic and heteroaromatic amides with unactivated alkenes, allyl acetates and allyl alcohols is described. This method offers an efficient route for the synthesis of vinyl and allyl benzamides in a highly stereoselective manner. It is observed that the ortho substituent on the benzamide moiety is crucial for the observation of allylated products in unactivated alkenes.

  5. Copper-catalyzed aerobic oxidative C-H functionalization of substituted pyridines: synthesis of imidazopyridine derivatives.

    Science.gov (United States)

    Yu, Jipan; Jin, Yunhe; Zhang, Hao; Yang, Xiaobo; Fu, Hua

    2013-12-02

    A novel, efficient, and practical method for the synthesis of imidazopyridine derivatives has been developed through the copper-catalyzed aerobic oxidative C-H functionalization of substituted pyridines with N-(alkylidene)-4H-1,2,4-triazol-4-amines. The procedure occurs by cleavage of the N-N bond in the N-(alkylidene)-4H-1,2,4-triazol-4-amines and activation of an aryl C-H bond in the substituted pyridines. This is the first example of the preparation of imidazopyridine derivatives by using pyridines as the substrates by transition-metal-catalyzed C-H functionalization. This method should provide a novel and efficient strategy for the synthesis of other nitrogen heterocycles. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Behavior of sphingomyelin and ceramide in a tear film lipid layer model

    Czech Academy of Sciences Publication Activity Database

    Olžyńska, Agnieszka; Cwiklik, Lukasz

    2017-01-01

    Roč. 210, MAR 2017 (2017), s. 128-134 ISSN 0940-9602 R&D Projects: GA ČR GA15-14292S Institutional support: RVO:61388955 Keywords : Molecular dynamics simulations * Sphingomyelin * Tear film lipid layer Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.864, year: 2016

  7. Influence of thermal processing on hydrolysis and stability of folate poly-gamma-glutamates in broccoli (Brassica oleracea var. italica), carrot (Daucus carota) and tomato (Lycopersicon esculentum).

    Science.gov (United States)

    Munyaka, Ann Wambui; Verlinde, Philippe; Mukisa, Ivan Muzira; Oey, Indrawati; Van Loey, Ann; Hendrickx, Marc

    2010-04-14

    The folate poly-gamma-glutamate profile, their concentrations, and hydrolysis by endogenous gamma-glutamyl hydrolase (GGH) were evaluated in broccoli, carrot and tomato. Further studies on the effect of time and temperature on folate poly-gamma-glutamate hydrolysis and stability were carried out in broccoli since this vegetable showed the highest long-chain and total folate poly-gamma-glutamate concentration. The evolution of l-ascorbic acid, total phenols and Trolox equivalent antioxidant capacity (TEAC) values was evaluated in parallel. Upon thermal inactivation of GGH prior to crushing, it was observed that broccoli, carrot and tomato contained poly-gamma-glutamates with one to seven glutamate residues but differed in the predominant poly-gamma-glutamates. Crushing of raw broccoli, carrot and tomato resulted in significant poly-gamma-glutamate profile changes in broccoli and carrot (indicating GGH-catalyzed hydrolysis) but not in tomato. In this study, the actual crushing of raw broccoli matrix had a greater effect on folate poly-gamma-glutamate hydrolysis than incubation conditions (0-30 min at 25-55 degrees C). During treatments at 25-140 degrees C, folate retention was higher at 80 and 100 degrees C than at the other temperatures. A similar trend in thermal stability was observed for folates, vitamin C, total phenols and TEAC value, an indication that conditions that result in endogenous antioxidants degradation might also result in folate degradation.

  8. Sphingomyelin exhibits greatly enhanced protection compared with egg yolk phosphatidylcholine against detergent bile salts

    NARCIS (Netherlands)

    Moschetta, A.; vanBerge-Henegouwen, G. P.; Portincasa, P.; Palasciano, G.; Groen, A. K.; van Erpecum, K. J.

    2000-01-01

    Inclusion of phosphatidylcholine within bile salt micelles protects against bile salt-induced cytotoxicity. In addition to phosphatidylcholine, bile may contain significant amounts of sphingomyelin, particularly under cholestatic conditions. We compared protective effects of egg yolk

  9. Enzymatic hydrolysis of 1-monoacyl-SN-glycerol-3-phosphoryl-choline (1-lysolecithin) by phospholipases from peanut seeds.

    Science.gov (United States)

    Strauss, H; Leibovitz-Ben Gershon, Z; Heller, M

    1976-06-01

    Hydrolysis of 1-lysolecithin (1-acyl glycerophosphorylcholine [1-acyl GPC]) by preparations of phospholipase D from peanut seeds was investigated. 1-Lysolecithin was hydrolyzed at a much slower rate than phosphatidylcholine (lecithin). Although Ca+2 ions are required for the cleavage of lecithin by the enzyme, their effect on the hydrolysis of lysolecithin depended upon the concentration of the substrate: at 0.2 mM 1-lysolecithin, Ca+2 ions increased the reaction rates, whereas at concentrations of the substrate lower than 0.1 mM, Ca+2 ions were inhibitory. A broad pH activity curve between 5 and 8 was obtained with higher rates in the alkaline range, both in the absence and presence of Ca+2 ions. The increased hydrolysis of lysolecithin due to Ca+2 was noticed over the entire pH range. Upon storage of the enzyme solutions at 4 C, decreased rates of hydrolysis of lecithin were observed, with t 1/2 values of ca. 50 and 100 days depending on the purity of the preparation. During the same period, no reduction occurred in the activity of these preparations on lysolecithin as substrate. The effects of Ca+2 ions and the analysis of the products of 1-acyl GPC cleavage by the enzyme preparations revealed the presence of more than one enzyme and the formation of the following compounds: lysophosphatidic acids (1 acyl glycerophosphoric acids), free fatty acids, glycerophosphorylcholine, and choline. The possible pathways leading to the degradation of lysolecithin and the formation of these products include reactions catalyzed by lysophospholipase A1 (lysophosphatidylcholine 1-acyl hydrolase, E.C. 3.1.1.5) and a phosphodiesterase (L-3-glycerylphosphorylcholine glycerophosphohydrolase, E.C.3.1.4.2), in addition to phospholipase D (phosphatidyl-choline phosphatidohydrolase, E.C. 3.1.4.4).

  10. Transgalactosylation/Hydrolysis Ratios of Various β-Galactosidases Catalyzing Alkyl-β-Galactoside Synthesis in Single-Phased Alcohol Media

    Directory of Open Access Journals (Sweden)

    Eleonora Winkelhausen

    2008-01-01

    Full Text Available Three microbial galactosidases, Aspergillus oryzae, Escherichia coli and Kluyveromyces marxianus β-galactosidase, were used as catalysts for transgalactosylation synthesis of alkyl-β-galactosides in single-phased alcohol media. Their selectivity towards different alcohol nucleophiles was quantified by determining the transgalactosylation/hydrolysis ratio in the water/alcohol mixtures containing water in concentrations below the level of saturation. p-Nitrophenyl-β-galactoside was used as a glycosyl donor at a concentration of 10 mM. Both the total reaction rate (transgalactosylation+hydrolysis and the ratio between the transgalactosylation (alcoholysis and hydrolysis increased with the increase of water activity. Although the A. oryzae β-galactosidase showed relatively low total activity (3.13 μmol/(min·mg protein, it exhibited the highest selectivity towards the hexanol nucleophile among the examined enzymes (0.65. The selectivity values in all the examined cases were below one, which implies that the hydrolysis, and not the synthesis, was the dominating reaction. The total reaction rate (transgalactosylation+hydrolysis was strongly affected by the water activity, and for the specific water activity in the different alcohols, it increased in the following order: n-octanol, n-hexanol, n-butanol.

  11. ENZYMATIC HYDROLYSIS OF SWITCHGRASS AND COASTAL BERMUDA GRASS PRETREATED USING DIFFERENT CHEMICAL METHODS

    Directory of Open Access Journals (Sweden)

    Jiele Xu

    2011-06-01

    Full Text Available To investigate the effects of biomass feedstock and pretreatment method on the enzyme requirement during hydrolysis, swichgrass and coastal Bermuda grass pretreated using H2SO4, NaOH, and Ca(OH2 at the optimal conditions were subjected to enzymatic hydrolysis using two enzyme combinations: NS 50013 + NS 50010 and Cellic CTec + Cellic HTec. The enzyme loadings were optimized, and correlations between feedstock property, pretreatment strategy, and enzyme usage were evaluated. The results show that pretreatment methods resulting in greater lignin contents in the pretreated biomass were generally associated with higher enzyme requirements. More sugars could be recovered from alkaline-pretreated biomass during enzymatic hydrolysis due to the better carbohydrate preservation achieved at mild pretreatment temperatures. The cellulase enzyme, Cellic CTec, was more efficient in catalyzing the hydrolysis of coastal Bermuda grass, a feedstock more digestible than the pretreated swichgrass, following pretreatment with NaOH or Ca(OH2.

  12. Kinetic study of the hydrolysis of 1-(4-nitrophenyl)-3-methyltriazene in aqueous solution and in the presence of surfactants.

    Science.gov (United States)

    Ebert, C; Lassiani, L; Linda, P; Lovrecich, M; Nisi, C; Rubessa, F

    1984-12-01

    The hydrolysis of 1-(4-nitrophenyl)-3-methyltriazene in aqueous solution has been studied over a pH range of 3-14. The effect of the anionic and cationic surfactants (sodium lauryl sulfate and hexadecyltrimethylammonium bromide) on the rate of hydrolysis was investigated. The quaternary ammonium bromide causes a rate decrease at all pH values studied, while sodium lauryl sulfate enhances the acid-catalyzed hydrolysis and decreases the observed rate constants in the pH-independent region. The results are discussed in terms of the current theory of micellar effects.

  13. Laccase-catalyzed C-S and C-C coupling for a one-pot synthesis of 1,4-naphthoquinone sulfides and 1,4-naphthoquinone sulfide dimers

    CSIR Research Space (South Africa)

    Wellington, Kevin W

    2013-06-01

    Full Text Available Oxidative C-S and C-C bond formation with aryl and alkyl thiols was catalyzed under mild conditions in a reaction vessel open to air at pH 4.5 in the presence of a commercial laccase (Novozym 51003 or Suberase) and a cosolvent (DMF) to afford 1...

  14. Microwave Energy Increases Fatty Acid Methyl Ester Yield in Human Whole Blood Due to Increased Sphingomyelin Transesterification.

    Science.gov (United States)

    Metherel, Adam H; Aristizabal Henao, Juan J; Ciobanu, Flaviu; Taha, Ameer Y; Stark, Ken D

    2015-09-01

    Dried blood spots (DBS) by fingertip prick collection for fatty acid profiling are becoming increasingly popular due to ease of collection, minimal invasiveness and its amenability to high-throughput analyses. Herein, we assess a microwave-assisted direct transesterification method for the production of fatty acid methyl esters (FAME) from DBS. Technical replicates of human whole blood were collected and 25-μL aliquots were applied to chromatography strips prior to analysis by a standard 3-h transesterification method or microwave-assisted direct transesterification method under various power (variable vs constant), time (1-5 min) and reagent (1-10% H2SO4 in methanol) conditions. In addition, a standard method was compared to a 5-min, 30-W power microwave in 1% H2SO4 method for FAME yield from whole blood sphingomyelin, and sphingomyelin standards alone and spiked in whole blood. Microwave-assisted direct transesterification yielded no significant differences in both quantitative (nmol/100 µL) and qualitative (mol%) fatty acid assessments after as little as 1.5- and 1-min reaction times, respectively, using the variable power method and 5% H2SO4 in methanol. However, 30-W power for 5 min increased total FAME yield of the technical replicates by 14%. This increase appears largely due to higher sphingomyelin-derived FAME yield of up to 109 and 399% compared to the standard method when determined from whole blood or pure standards, respectively. In conclusion, microwave-assisted direct transesterification of DBS achieved in as little as 1-min, and 5-min reaction times increase total fatty acids primarily by significantly improving sphingomyelin-derived fatty acid yield.

  15. Rh(III)-Catalyzed Synthesis of N-Unprotected Indoles from Imidamides and Diazo Ketoesters via C-H Activation and C-C/C-N Bond Cleavage.

    Science.gov (United States)

    Qi, Zisong; Yu, Songjie; Li, Xingwei

    2016-02-19

    The synthesis of N-unprotected indoles has been realized via Rh(III)-catalyzed C-H activation/annulation of imidamides with α-diazo β-ketoesters. The reaction occurs with the release of an amide coproduct, which originates from both the imidamide and the diazo as a result of C═N cleavage of the imidamide and C-C(acyl) cleavage of the diazo. A rhodacyclic intermediate has been isolated and a plausible mechanism has been proposed.

  16. Rhodium-Catalyzed C-C Bond Formation via Heteroatom-Directed C-H Bond Activation

    Energy Technology Data Exchange (ETDEWEB)

    Colby, Denise; Bergman, Robert; Ellman, Jonathan

    2010-05-13

    Once considered the 'holy grail' of organometallic chemistry, synthetically useful reactions employing C-H bond activation have increasingly been developed and applied to natural product and drug synthesis over the past decade. The ubiquity and relative low cost of hydrocarbons makes C-H bond functionalization an attractive alternative to classical C-C bond forming reactions such as cross-coupling, which require organohalides and organometallic reagents. In addition to providing an atom economical alternative to standard cross - coupling strategies, C-H bond functionalization also reduces the production of toxic by-products, thereby contributing to the growing field of reactions with decreased environmental impact. In the area of C-C bond forming reactions that proceed via a C-H activation mechanism, rhodium catalysts stand out for their functional group tolerance and wide range of synthetic utility. Over the course of the last decade, many Rh-catalyzed methods for heteroatom-directed C-H bond functionalization have been reported and will be the focus of this review. Material appearing in the literature prior to 2001 has been reviewed previously and will only be introduced as background when necessary. The synthesis of complex molecules from relatively simple precursors has long been a goal for many organic chemists. The ability to selectively functionalize a molecule with minimal pre-activation can streamline syntheses and expand the opportunities to explore the utility of complex molecules in areas ranging from the pharmaceutical industry to materials science. Indeed, the issue of selectivity is paramount in the development of all C-H bond functionalization methods. Several groups have developed elegant approaches towards achieving selectivity in molecules that possess many sterically and electronically similar C-H bonds. Many of these approaches are discussed in detail in the accompanying articles in this special issue of Chemical Reviews. One approach

  17. Cu-catalyzed esterification reaction via aerobic oxygenation and C-C bond cleavage: an approach to α-ketoesters.

    Science.gov (United States)

    Zhang, Chun; Feng, Peng; Jiao, Ning

    2013-10-09

    The Cu-catalyzed novel aerobic oxidative esterification reaction of 1,3-diones for the synthesis of α-ketoesters has been developed. This method combines C-C σ-bond cleavage, dioxygen activation and oxidative C-H bond functionalization, as well as provides a practical, neutral, and mild synthetic approach to α-ketoesters which are important units in many biologically active compounds and useful precursors in a variety of functional group transformations. A plausible radical process is proposed on the basis of mechanistic studies.

  18. Rh(I) -Catalyzed Intramolecular Carbonylative C-H/C-I Coupling of 2-Iodobiphenyls Using Furfural as a Carbonyl Source.

    Science.gov (United States)

    Furusawa, Takuma; Morimoto, Tsumoru; Nishiyama, Yasuhiro; Tanimoto, Hiroki; Kakiuchi, Kiyomi

    2016-08-19

    Synthesis of fluoren-9-ones by a Rh-catalyzed intramolecular C-H/C-I carbonylative coupling of 2-iodobiphenyls using furfural as a carbonyl source is presented. The findings indicate that the rate-determining step is not a C-H bond cleavage but, rather, the oxidative addition of the C-I bond to a Rh(I) center. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Hydrolysis of Letrozole catalyzed by macrocyclic Rhodium (I) Schiff-base complexes.

    Science.gov (United States)

    Reddy, P Muralidhar; Shanker, K; Srinivas, V; Krishna, E Ravi; Rohini, R; Srikanth, G; Hu, Anren; Ravinder, V

    2015-03-15

    Ten mononuclear Rhodium (I) complexes were synthesized by macrocyclic ligands having N4 and N2O2 donor sites. Square planar geometry is assigned based on the analytical and spectral properties for all complexes. Rh(I) complexes were investigated as catalysts in hydrolysis of Nitrile group containing pharmaceutical drug Letrozole. A comparative study showed that all the complexes are efficient in the catalysis. The percent yields of all the catalytic reaction products viz. drug impurities were determined by spectrophotometric procedures and characterized by spectral studies. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Rhodium(I)-catalyzed cycloisomerization of benzylallene-alkynes through C-H activation.

    Science.gov (United States)

    Kawaguchi, Yasuaki; Yasuda, Shigeo; Kaneko, Akira; Oura, Yuki; Mukai, Chisato

    2014-07-14

    The efficient Rh(I)-catalyzed cycloisomerization of benzylallene-alkynes produced the tricyclo[9.4.0.0(3,8)]pentadecapentaene skeleton through a C(sp2)-H bond activation in good yields. A plausible reaction mechanism proceeds via oxidative addition of the acetylenic C-H bond to Rh(I), an ene-type cyclization to the vinylidenecarbene-Rh(I) intermediate, and an electrophilic aromatic substitution with the vinylidenecarbene species. It was proposed based on deuteration and competition experiments. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Phospholipid transfer from vesicles to high density lipoproteins, catalyzed by human plasma phospholipid transfer protein

    International Nuclear Information System (INIS)

    Sweeny, S.A.

    1985-01-01

    Human plasma phospholipid transfer protein (PLTP) catalyzes the mass transfer of phosphatidylcholine (PC). Partial purification of PLTP yielded proteins with apparent M/sub r/ = 59,000 and 40,000 by SDS-PAGE. PLTP activity was measured by transfer of [ 14 C]L-α-dipalmitoyl PC from egg-PC vesicles to HDL. Activity was enhanced at low pH (4.5) upon addition of β-mercaptoethanol while Ca +2 and Na + had no effect. E/sub act/ for facilitated PC transfer was 18.2 +/- 2 kcal/mol. The donor specificity of PLTP was examined using vesicles containing egg-PC plus cholesterol or sphingomyelin. The fluidity of the donor membrane (measured by fluorescence polarization of diphenylhexatriene) correlated strongly with a decrease in PLTP activity. Phosphatidic acid did not affect activity. Increase in vesicle size reduced activity. The acceptor specificity of PLTP was examined using chemically modified HDL. PLTP activity increased up to 1.7-fold with an initial increase in negative charge and then decreased upon extensive modification. A mechanism is proposed where PLTP binds to vesicls and enhances the diffusion of PC into the medium where it is adsorbed by HDL

  2. 40 CFR 796.3500 - Hydrolysis as a function of pH at 25 °C.

    Science.gov (United States)

    2010-07-01

    ... Procedure 1 or 2 were employed in making concentration measurements, use a linear regression analysis with....3500 Hydrolysis as a function of pH at 25 °C. (a) Introduction—(1) Background and purpose. (i) Water is...

  3. Rhodium-catalyzed C-H alkynylation of arenes at room temperature.

    Science.gov (United States)

    Feng, Chao; Loh, Teck-Peng

    2014-03-03

    The rhodium(III)-catalyzed ortho C-H alkynylation of non-electronically activated arenes is disclosed. This process features a straightforward and highly effective protocol for the synthesis of functionalized alkynes and represents the first example of merging a hypervalent iodine reagent with rhodium(III) catalysis. Notably, this reaction proceeds at room temperature, tolerates a variety of functional groups, and more importantly, exhibits high selectivity for monoalkynylation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Adsorption and catalytic hydrolysis of carbaryl and atrazine on pig manure-derived biochars: Impact of structural properties of biochars

    International Nuclear Information System (INIS)

    Zhang, Peng; Sun, Hongwen; Yu, Li; Sun, Tieheng

    2013-01-01

    Highlights: ► High ash content biochar can increase solution pH and released metal ions. ► Ash in biochar can combine pesticide through specific interactions. ► Composition and structure of biochar is favor for the hydrolysis of pesticides. -- Abstract: Biochars were produced from pig manure to elucidate the influence of biochars with high ash contents on the fate of pesticides. Adsorption and catalytic hydrolysis of carbaryl and atrazine on original biochars and deashed biochars were investigated. The two pesticides were substantially adsorbed by the biochars, with organic carbon normalized sorption coefficient (K oc ) values of 10 2.65 –10 3.66 L/kg for carbaryl and 10 1.90 –10 3.57 L/kg for atrazine at C e of 0.5 mg/L. Hydrophobic effect alone could not explain the sorption, and several other processes including pore-filling and π–π electron donor–acceptor interactions were involved in pesticide adsorption. Adsorption increased greatly on the deashed biochar, indicating that some organic sorption sites in the original biochars were blocked or difficult to access due to their interactions with inorganic moiety. The pesticides were found to hydrolyze faster in the presence of biochars, and in the presence of biochar pyrolyzed at 700 °C, carbaryl and atrazine were decomposed by 71.8% and 27.9% in 12 h, respectively. The elevated solution pH was the main reason for the enhanced hydrolysis; however both the mineral surface and dissolved metal ions released from the biochars were confirmed to catalyze the hydrolysis

  5. Adsorption and catalytic hydrolysis of carbaryl and atrazine on pig manure-derived biochars: Impact of structural properties of biochars

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Peng, E-mail: phevos1983@yahoo.com.cn [MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071 (China); Sun, Hongwen, E-mail: sunhongwen@nankai.edu.cn [MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071 (China); Yu, Li [MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071 (China); Sun, Tieheng [Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016 (China)

    2013-01-15

    Highlights: ► High ash content biochar can increase solution pH and released metal ions. ► Ash in biochar can combine pesticide through specific interactions. ► Composition and structure of biochar is favor for the hydrolysis of pesticides. -- Abstract: Biochars were produced from pig manure to elucidate the influence of biochars with high ash contents on the fate of pesticides. Adsorption and catalytic hydrolysis of carbaryl and atrazine on original biochars and deashed biochars were investigated. The two pesticides were substantially adsorbed by the biochars, with organic carbon normalized sorption coefficient (K{sub oc}) values of 10{sup 2.65}–10{sup 3.66} L/kg for carbaryl and 10{sup 1.90}–10{sup 3.57} L/kg for atrazine at C{sub e} of 0.5 mg/L. Hydrophobic effect alone could not explain the sorption, and several other processes including pore-filling and π–π electron donor–acceptor interactions were involved in pesticide adsorption. Adsorption increased greatly on the deashed biochar, indicating that some organic sorption sites in the original biochars were blocked or difficult to access due to their interactions with inorganic moiety. The pesticides were found to hydrolyze faster in the presence of biochars, and in the presence of biochar pyrolyzed at 700 °C, carbaryl and atrazine were decomposed by 71.8% and 27.9% in 12 h, respectively. The elevated solution pH was the main reason for the enhanced hydrolysis; however both the mineral surface and dissolved metal ions released from the biochars were confirmed to catalyze the hydrolysis.

  6. Kinetics of aggregation growth with competition between catalyzed birth and catalyzed death

    International Nuclear Information System (INIS)

    Wang Haifeng; Gao Yan; Lin Zhenquan

    2008-01-01

    An aggregation growth model of three species A, B and C with the competition between catalyzed birth and catalyzed death is proposed. Irreversible aggregation occurs between any two aggregates of the like species with the constant rate kernels I n (n = 1,2,3). Meanwhile, a monomer birth of an A species aggregate of size k occurs under the catalysis of a B species aggregate of size j with the catalyzed birth rate kernel K(k,j) = Kkj v and a monomer death of an A species aggregate of size k occurs under the catalysis of a C species aggregate of size j with the catalyzed death rate kernel L(k,j)=Lkj v , where v is a parameter reflecting the dependence of the catalysis reaction rates of birth and death on the size of catalyst aggregate. The kinetic evolution behaviours of the three species are investigated by the rate equation approach based on the mean-field theory. The form of the aggregate size distribution of A species a k (t) is found to be dependent crucially on the competition between the catalyzed birth and death of A species, as well as the irreversible aggregation processes of the three species: (1) In the v k (t) satisfies the conventional scaling form; (2) In the v ≥ 0 case, the competition between the catalyzed birth and death dominates the process. When the catalyzed birth controls the process, a k (t) takes the conventional or generalized scaling form. While the catalyzed death controls the process, the scaling description of the aggregate size distribution breaks down completely

  7. Stoichiometry of ATP hydrolysis and chlorophyllide formation of dark-operative protochlorophyllide oxidoreductase from Rhodobacter capsulatus

    Energy Technology Data Exchange (ETDEWEB)

    Nomata, Jiro [Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601 (Japan); Terauchi, Kazuki [Department of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577 (Japan); Fujita, Yuichi, E-mail: fujita@agr.nagoya-u.ac.jp [Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601 (Japan)

    2016-02-12

    Dark-operative protochlorophyllide (Pchlide) oxidoreductase (DPOR) is a nitrogenase-like enzyme catalyzing a reduction of the C17 = C18 double bond of Pchlide to form chlorophyllide a (Chlide) in bacteriochlorophyll biosynthesis. DPOR consists of an ATP-dependent reductase component, L-protein (a BchL dimer), and a catalytic component, NB-protein (a BchN–BchB heterotetramer). The L-protein transfers electrons to the NB-protein to reduce Pchlide, which is coupled with ATP hydrolysis. Here we determined the stoichiometry of ATP hydrolysis and the Chlide formation of DPOR. The minimal ratio of ATP to Chlide (ATP/2e{sup –}) was 4, which coincides with that of nitrogenase. The ratio increases with increasing molar ratio of L-protein to NB-protein. This profile differs from that of nitrogenase. These results suggest that DPOR has a specific intrinsic property, while retaining the common features shared with nitrogenase. - Highlights: • The stoichiometry of nitrogenase-like protochlorophyllide reductase was determined. • The minimal ATP/2e{sup –} ratio was 4, which coincides with that of nitrogenase. • The ATP/2e{sup –} ratio increases with increasing L-protein/NB-protein molar ratio. • DPOR has an intrinsic property, but retains features shared with nitrogenase.

  8. Hydrolysis of uranium monocarbide

    International Nuclear Information System (INIS)

    Hajek, B.; Karen, P.; Brozek, V.

    1984-01-01

    The substoichiometric uranium monocarbide UCsub(0.95) was hydrolyzed in acid medium at 80 degC. The composition of the products of hydrolysis corresponds to published data but it correlates better with the stoichiometric composition of the hydrolyzable carbide. The mechanisms of the hydrolytic reaction are discussed and a modified radical mechanism is suggested based on the concept of initiation of the radical process by Hsup(.) radicals formed owing to the nonstoichiometry of the substance. A relation is proposed for calculating the content of free hydrogen in the hydrolysis products of carbides of metallic nature for which a radical mechanism of their reaction with water can be assumed. Some effects occurring during the hydrolysis of uranium carbide, as described in literature, are explained in terms of the concept suggested. The results obtained by the authors for carbides of manganese (Mn 7 C 3 ) and for rare earth elements are discussed. (author)

  9. Ruthenium-catalyzed direct C3 alkylation of indoles with α,β-unsaturated ketones.

    Science.gov (United States)

    Li, Shuai-Shuai; Lin, Hui; Zhang, Xiao-Mei; Dong, Lin

    2015-01-28

    In this paper, a simple and highly efficient ruthenium-catalyzed direct C3 alkylation of indoles with various α,β-unsaturated ketones without chelation assistance has been developed. This novel C-H activation methodology exhibits a broad substrate scope such as different substituted indoles, pyrroles, and other azoles. Further synthetic applications of the alkylation products can lead to more attractive 3,4-fused tricyclic indoles.

  10. Poly(N-vinyl-2-pyrrolidone)-stabilized palladium-platinum nanoparticles-catalyzed hydrolysis of ammonia borane for hydrogen generation

    Science.gov (United States)

    Rakap, Murat

    2015-02-01

    The catalytic use of highly efficient poly(N-vinyl-2-pyrrolidone)-stabilized palladium-platinum nanoparticles (4.2 ± 1.9 nm) in the hydrolysis of ammonia-borane is reported. The catalyst is prepared by co-reduction of two metal ions in ethanol/water mixture by an alcohol reduction method and characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and UV-Vis spectroscopy. They are recyclable and highly active for hydrogen generation from the hydrolysis of ammonia-borane even at very low concentrations and temperature, providing a record numbers of average turnover frequency value (125 mol H2/mol cat.min-1) and maximum hydrogen generation rate (3468 L H2 min-1 (mol cat)-1). They also provide activation energy of 51.7 ± 2 kJ/mol for the hydrolysis of ammonia borane.

  11. Data characterizing the energetics of enzyme-catalyzed hydrolysis and transglycosylation reactions by DFT cluster model calculations

    Directory of Open Access Journals (Sweden)

    Jitrayut Jitonnom

    2018-04-01

    Full Text Available The data presented in this paper are related to the research article entitled “QM/MM modeling of the hydrolysis and transfructosylation reactions of fructosyltransferase from Aspergillus japonicas, an enzyme that produces prebiotic fructooligosaccharide” (Jitonnom et al., 2018 [1]. This paper presents the procedure and data for characterizing the whole relative energy profiles of hydrolysis and transglycosylation reactions whose elementary steps differ in chemical composition. The data also reflects the choices of the QM cluster model, the functional/basis set method and the equations in determining the reaction energetics.

  12. Highly enantioselective rhodium(I)-catalyzed carbonyl carboacylations initiated by C-C bond activation.

    Science.gov (United States)

    Souillart, Laetitia; Cramer, Nicolai

    2014-09-01

    The lactone motif is ubiquitous in natural products and pharmaceuticals. The Tishchenko disproportionation of two aldehydes, a carbonyl hydroacylation, is an efficient and atom-economic access to lactones. However, these reaction types are limited to the transfer of a hydride to the accepting carbonyl group. The transfer of alkyl groups enabling the formation of CC bonds during the ester formation would be of significant interest. Reported herein is such asymmetric carbonyl carboacylation of aldehydes and ketones, thus affording complex bicyclic lactones in excellent enantioselectivities. The rhodium(I)-catalyzed transformation is induced by an enantiotopic CC bond activation of a cyclobutanone and the formed rhodacyclic intermediate reacts with aldehyde or ketone groups to give highly functionalized lactones. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Rhodium Catalyzed Annulation of N-Benzoylsulfonamide with Isocyanide via C-H Activation

    Science.gov (United States)

    Zhu, Chen; Xie, Weiqing; Falck, John R.

    2012-01-01

    Isocyanide insertion: the first rhodium-catalyzed annulation of N-benzoylsulfonamide incorporating with isocyanide via C-H activation is described. The transformation is broadly compatible with N-benzoylsulfonamides bearing various electron-properties as well as isocyanides. From practical point of view, this methodology provides the most straightforward approach to a series of 3-(imino)isoindolinones. PMID:21972033

  14. By-Product Carrying Humidified Hydrogen: An Underestimated Issue in the Hydrolysis of Sodium Borohydride.

    Science.gov (United States)

    Petit, Eddy; Miele, Philippe; Demirci, Umit B

    2016-07-21

    Catalyzed hydrolysis of sodium borohydride generates up to four molecules of hydrogen, but contrary to what has been reported so far, the humidified evolved gas is not pure hydrogen. Elemental and spectroscopic analyses show, for the first time, that borate by-products pollute the stream as well as the vessel. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Rhodium-Catalyzed Regioselective C7-Olefination of Indazoles Using an N-Amide Directing Group.

    Science.gov (United States)

    Guo, Lei; Chen, Yanyu; Zhang, Rong; Peng, Qiujun; Xu, Lanting; Pan, Xianhua

    2017-02-01

    A rhodium-catalyzed regioselective C-H olefination of indazole is described. This protocol relies on the use of an efficient and removable N,N-diisopropylcarbamoyl directing group, which offers facile access to C7-olefinated indazoles with high regioselectivity, ample substrate scope and broad functional group tolerance. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Site-specific DNA transesterification catalyzed by a restriction enzyme

    OpenAIRE

    Sasnauskas, Giedrius; Connolly, Bernard A.; Halford, Stephen E.; Siksnys, Virginijus

    2007-01-01

    Most restriction endonucleases use Mg2+ to hydrolyze phosphodiester bonds at specific DNA sites. We show here that BfiI, a metal-independent restriction enzyme from the phospholipase D superfamily, catalyzes both DNA hydrolysis and transesterification reactions at its recognition site. In the presence of alcohols such as ethanol or glycerol, it attaches the alcohol covalently to the 5′ terminus of the cleaved DNA. Under certain conditions, the terminal 3′-OH of one DNA strand can attack the t...

  17. Hydrolysis of alkaline pretreated banana peel

    Science.gov (United States)

    Fatmawati, A.; Gunawan, K. Y.; Hadiwijaya, F. A.

    2017-11-01

    Banana peel is one of food wastes that are rich in carbohydrate. This shows its potential as fermentation substrate including bio-ethanol. This paper presented banana peel alkaline pretreatment and enzymatic hydrolysis. The pretreatment was intended to prepare banana peel in order to increase hydrolysis performance. The alkaline pretreatment used 10, 20, and 30% w/v NaOH solution and was done at 60, 70 and 80°C for 1 hour. The hydrolysis reaction was conducted using two commercial cellulose enzymes. The reaction time was varied for 3, 5, and 7 days. The best condition for pretreatment process was one conducted using 30% NaOH solution and at 80°C. This condition resulted in cellulose content of 90.27% and acid insoluble lignin content of 2.88%. Seven-day hydrolysis time had exhibited the highest reducing sugar concentration, which was7.2869 g/L.

  18. Polymeric amylase nanoparticles as a new semi-synthetic enzyme system for hydrolysis of starch

    International Nuclear Information System (INIS)

    Say, R.; Şenay, R. Hilal; Biçen, Özlem; Ersöz, Arzu; Şişman Yılmaz, Filiz; Akgöl, Sinan; Denizli, Adil

    2013-01-01

    α-Amylase (EC 3.2.1.1; α-D-1,4,glucan glucanohydrolase) catalyzes the hydrolysis of α-D-(1,4)-glucosidic linkages in starch, glycogen, and various malto-oligosaccharides, by releasing α-anomeric products. In this study, a novel method has been developed to prepare nanoprotein particles that carry α-amylase as a monomer by using a photosensitive microemulsion polymerization process. The nanostructured α-amylase with photosensitive features have been characterized by fluorescence spectroscopy, transmission electron microscopy (TEM) and Zeta Sizer. The fluorescence intensity of amylase nanoparticles was determined to be 658 a.u. at 610 nm and the average particle size of nanoamylase was found to be about 71.8 nm. Both free α-amylase and nanoparticles were used in the hydrolysis of starch under varying reaction conditions such as pH and temperature that affect enzyme activity and the results were compared to each other. K m values were 0.26 and 0.87 mM and V max values were 0.36 IU mg −1 and 22.32 IU mg −1 for nanoenzyme and free enzyme, respectively. Then, thermal stability, storage stability and reusability were investigated and according to the results, activity was preserved 60% at 60 °C; 20% at 70–80 °C temperature values and 80% after 105 days storage. Finally after 10 cycles, the activity was preserved 90% and this novel enzymatic polymeric amylase nanoparticle has showed considerable potential as reusable catalyst. - Highlights: ► Developing to prepare nanoprotein particles carrying α-amylase ► Characterization of nanostructured α-amylase ► Usability of α-amylase nanoparticles in hydrolysis of starch

  19. Polymeric amylase nanoparticles as a new semi-synthetic enzyme system for hydrolysis of starch

    Energy Technology Data Exchange (ETDEWEB)

    Say, R. [Anadolu University, Faculty of Science, Chemistry Department, Yunus Emre Campus, Eskişehir (Turkey); Şenay, R. Hilal [Ege University, Faculty of Science, Biochemistry Department, 35100 Bornova-Izmir (Turkey); Biçen, Özlem; Ersöz, Arzu; Şişman Yılmaz, Filiz [Anadolu University, Faculty of Science, Chemistry Department, Yunus Emre Campus, Eskişehir (Turkey); Akgöl, Sinan, E-mail: sinanakgol@yahoo.co.uk [Ege University, Faculty of Science, Biochemistry Department, 35100 Bornova-Izmir (Turkey); Denizli, Adil [Hacettepe University, Faculty of Science, Chemistry Department, 06532 Ankara (Turkey)

    2013-05-01

    α-Amylase (EC 3.2.1.1; α-D-1,4,glucan glucanohydrolase) catalyzes the hydrolysis of α-D-(1,4)-glucosidic linkages in starch, glycogen, and various malto-oligosaccharides, by releasing α-anomeric products. In this study, a novel method has been developed to prepare nanoprotein particles that carry α-amylase as a monomer by using a photosensitive microemulsion polymerization process. The nanostructured α-amylase with photosensitive features have been characterized by fluorescence spectroscopy, transmission electron microscopy (TEM) and Zeta Sizer. The fluorescence intensity of amylase nanoparticles was determined to be 658 a.u. at 610 nm and the average particle size of nanoamylase was found to be about 71.8 nm. Both free α-amylase and nanoparticles were used in the hydrolysis of starch under varying reaction conditions such as pH and temperature that affect enzyme activity and the results were compared to each other. K{sub m} values were 0.26 and 0.87 mM and V{sub max} values were 0.36 IU mg{sup −1} and 22.32 IU mg{sup −1} for nanoenzyme and free enzyme, respectively. Then, thermal stability, storage stability and reusability were investigated and according to the results, activity was preserved 60% at 60 °C; 20% at 70–80 °C temperature values and 80% after 105 days storage. Finally after 10 cycles, the activity was preserved 90% and this novel enzymatic polymeric amylase nanoparticle has showed considerable potential as reusable catalyst. - Highlights: ► Developing to prepare nanoprotein particles carrying α-amylase ► Characterization of nanostructured α-amylase ► Usability of α-amylase nanoparticles in hydrolysis of starch.

  20. Modulation of cellulase activity by charged lipid bilayers with different acyl chain properties for efficient hydrolysis of ionic liquid-pretreated cellulose.

    Science.gov (United States)

    Mihono, Kai; Ohtsu, Takeshi; Ohtani, Mai; Yoshimoto, Makoto; Kamimura, Akio

    2016-10-01

    The stability of cellulase activity in the presence of ionic liquids (ILs) is critical for the enzymatic hydrolysis of insoluble cellulose pretreated with ILs. In this work, cellulase was incorporated in the liposomes composed of negatively charged 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) and zwitterionic phosphatidylcholines (PCs) with different length and degree of unsaturation of the acyl chains. The liposomal cellulase-catalyzed reaction was performed at 45°C in the acetate buffer solution (pH 4.8) with 2.0g/L CC31 as cellulosic substrate. The crystallinity of CC31 was reduced by treating with 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) at 120°C for 30min. The liposomal cellulase continuously catalyzed hydrolysis of the pretreated CC31 for 48h producing glucose in the presence of 15wt% [Bmim]Cl. The charged lipid membranes were interactive with [Bmim](+), as elucidated by the [Bmim]Cl-induced alterations in fluorescence polarization of the membrane-embedded 1,6-diphenyl-1,3,5-hexatriene (DPH) molecules. The charged membranes offered the microenvironment where inhibitory effects of [Bmim]Cl on the cellulase activity was relieved. The maximum glucose productivity GP of 10.8 mmol-glucose/(hmol-lipid) was obtained at the reaction time of 48h with the cellulase incorporated in the liposomes ([lipid]=5.0mM) composed of 50mol% POPG and 1,2-dilauroyl-sn-glycero-3-phosohocholine (DLPC) with relatively short and saturated acyl chains. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. The Golgi localization of phosphatidylinositol transfer protein beta requires the protein kinase C-dependent phosphorylation of serine 262 and is essential for maintaining plasma membrane sphingomyelin levels.

    Science.gov (United States)

    van Tiel, Claudia M; Westerman, Jan; Paasman, Marten A; Hoebens, Martha M; Wirtz, Karel W A; Snoek, Gerry T

    2002-06-21

    Recombinant mouse phosphatidylinositol transfer protein (PI-TP)beta is a substrate for protein kinase C (PKC)-dependent phosphorylation in vitro. Based on site-directed mutagenesis and two-dimensional tryptic peptide mapping, Ser(262) was identified as the major site of phosphorylation and Ser(165) as a minor phosphorylation site. The phospholipid transfer activities of wild-type PI-TP beta and PI-TP beta(S262A) were identical, whereas PI-TP beta(S165A) was completely inactive. PKC-dependent phosphorylation of Ser(262) also had no effect on the transfer activity of PI-TP beta. To investigate the role of Ser(262) in the functioning of PI-TP beta, wtPI-TP beta and PI-TP beta(S262A) were overexpressed in NIH3T3 fibroblast cells. Two-dimensional PAGE analysis of cell lysates was used to separate PI-TP beta from its phosphorylated form. After Western blotting, wtPI-TP beta was found to be 85% phosphorylated, whereas PI-TP beta(S262A) was not phosphorylated. In the presence of the PKC inhibitor GF 109203X, the phosphorylated form of wtPI-TP beta was strongly reduced. Immunolocalization showed that wtPI-TP beta was predominantly associated with the Golgi membranes. In the presence of the PKC inhibitor, wtPI-TP beta was distributed throughout the cell similar to what was observed for PI-TP beta(S262A). In contrast to wtPI-TP beta overexpressors, cells overexpressing PI-TP beta(S262A) were unable to rapidly replenish sphingomyelin in the plasma membrane upon degradation by sphingomyelinase. This implies that PKC-dependent association with the Golgi complex is a prerequisite for PI-TP beta to express its effect on sphingomyelin metabolism.

  2. Acid-functionalized nanoparticles for biomass hydrolysis

    Science.gov (United States)

    Pena Duque, Leidy Eugenia

    Cellulosic ethanol is a renewable source of energy. Lignocellulosic biomass is a complex material composed mainly of cellulose, hemicellulose, and lignin. Biomass pretreatment is a required step to make sugar polymers liable to hydrolysis. Mineral acids are commonly used for biomass pretreatment. Using acid catalysts that can be recovered and reused could make the process economically more attractive. The overall goal of this dissertation is the development of a recyclable nanocatalyst for the hydrolysis of biomass sugars. Cobalt iron oxide nanoparticles (CoFe2O4) were synthesized to provide a magnetic core that could be separated from reaction using a magnetic field and modified to carry acid functional groups. X-ray diffraction (XRD) confirmed the crystal structure was that of cobalt spinel ferrite. CoFe2O4 were covered with silica which served as linker for the acid functions. Silica-coated nanoparticles were functionalized with three different acid functions: perfluoropropyl-sulfonic acid, carboxylic acid, and propyl-sulfonic acid. Transmission electron microscope (TEM) images were analyzed to obtain particle size distributions of the nanoparticles. Total carbon, nitrogen, and sulfur were quantified using an elemental analyzer. Fourier transform infra-red spectra confirmed the presence of sulfonic and carboxylic acid functions and ion-exchange titrations accounted for the total amount of catalytic acid sites per nanoparticle mass. These nanoparticles were evaluated for their performance to hydrolyze the beta-1,4 glycosidic bond of the cellobiose molecule. Propyl-sulfonic (PS) and perfluoropropyl-sulfonic (PFS) acid functionalized nanoparticles catalyzed the hydrolysis of cellobiose significantly better than the control. PS and PFS were also evaluated for their capacity to solubilize wheat straw hemicelluloses and performed better than the control. Although PFS nanoparticles were stronger acid catalysts, the acid functions leached out of the nanoparticle during

  3. Cobalt-Catalyzed, Aminoquinoline-Directed sp2 C-H Bond Alkenylation by Alkynes**

    Science.gov (United States)

    Grigorjeva, Liene; Daugulis, Olafs

    2014-01-01

    We have developed a method for cobalt-catalyzed, aminoquinoline- and picolinamide-directed sp2 C-H bond alkenylation by alkynes. Method shows excellent functional group tolerance and both internal and terminal alkynes are competent substrates for the coupling. The reaction employs Co(OAc)2*4H2O catalyst, Mn(OAc)2 cocatalyst, and oxygen from air as a terminal oxidant. PMID:25060365

  4. Palladium-catalyzed C-H olefination of uracils and caffeines using molecular oxygen as the sole oxidant.

    Science.gov (United States)

    Zhang, Xinyu; Su, Lv; Qiu, Lin; Fan, Zhenwei; Zhang, Xiaofeng; Lin, Shen; Huang, Qiufeng

    2017-04-18

    The palladium-catalyzed oxidative C-H olefination of uracils or caffeines with alkenes using an atmospheric pressure of molecular oxygen as the sole oxidant has been disclosed. This novel strategy offers an efficient and environmentally friendly method to biologically important C5-alkene uracil derivatives or C8-alkene caffeine derivatives.

  5. Catalytic versatility of Bacillus pumilus β-xylosidase: glycosyl transfer and hydrolysis promoted with α- and β-D-xylosyl fluoride

    International Nuclear Information System (INIS)

    Kasumi, T.; Tsumuraya, Y.; Brewer, C.F.; Kersters-Hilderson, H.; Claeyssens, M.; Hehre, E.J.

    1987-01-01

    Bacillus pumilus β-xylosidase, an enzyme considered restricted to hydrolyzing a narrow range of β-D-xylosidic substrates with inversion of configuration, was found to catalyze different stereochemical, essentially irreversible, glycosylation reactions with α- and β-D-xylopyranosyl fluoride. The enzyme promoted the hydrolysis of β-D-xylopyranosyl fluoride at a high rate, V = 6.25 μmol min -1 mg -1 at 0 0 C, in a reaction that obeyed Michaelis-Menten kinetics. In contrast, its action upon α-D-xylopyranosyl fluoride was slow and characterized by an unusual relation between the rate of fluoride release and the substrate concentration, suggesting the possible need for two substrate molecules to be bound at the active center in order for reaction to occur. Moreover, 1 H NMR spectra of a digest of α-D-xylosyl fluoride showed the substrate to be specifically converted to α-D-xylose by the enzyme. The observed retention of configuration is not consistent with direct hydrolysis by this inverting enzyme but is strongly indicative of the occurrence of two successive inverting reactions: xylosyl transfer from α-D-xylosyl fluoride to form a β-D-xylosidic product, followed by hydrolysis of the latter to produce α-D-xylose. The transient intermediate product formed enzymically from α-D-xylosyl fluoride in the presence of [ 14 C]xylose was isolated and shown by its specific radioactivity and 1 H NMR spectrum as well as by methylatino and enzymic analyses to be 4-O-β-D-xylopyranosyl-D-xylopyranose containing one [ 14 C]xylose residue

  6. Initial Stages in the Rhodium(III)-Catalyzed C-H Bond Activation of Primary Alcohols in Aqueous Solution

    DEFF Research Database (Denmark)

    Eriksen, J.; Monsted, L.; Monsted, O.

    2010-01-01

    The mechanism of the catalytic HID exchange in primary alcohol substrates derived from aldopentoses, promoted by a macrocyclic rhodium(III) complex, has been shown to occur by a reversible redox reaction that gives aldehyde and a rhodium hydride complex. Hydride exchange in the latter complex...... promotes the introduction of solvent hydrogen in the primary alcohol formed by the reverse reaction. The hydride complex has been crystallographically characterized as a trifluoromethanesulfonate salt that contains the trans-[Rh(cycb)(H)(OH2)](2+) (cycb = rac-5,5,7,12,12,14-hexamethyl-1......,4,8,11-tetraazacyclotetradecane) cation. The hydride complex is stable for extended periods of time in acidic solution in the absence of oxidants. In basic solutions a series of base-catalyzed reactions take place to yield ultimately the same mixture of [Rh(cycb)(OH)(2)](+) isomers as produced by base hydrolysis of the trans...

  7. Synthesis of heterocycles via transition-metal-catalyzed hydroarylation of alkynes.

    Science.gov (United States)

    Yamamoto, Yoshihiko

    2014-03-07

    Transition-metal (TM)-catalyzed hydroarylation reactions of alkynes have received much attention, because they enable the net insertion of alkyne C-C triple bonds into C-H bonds of aromatic precursors, resulting in regio- and stereo-selective formation of synthetically useful arylalkenes. Taking advantage of this feature, TM-catalyzed alkyne hydroarylations have been successfully used for the synthesis of heterocycles. TM-catalyzed alkyne hydroarylations can be classified into three major categories depending on the type of reaction and precursors involved: (1) palladium-catalyzed reductive Heck reactions of alkynes with aryl halides, (2) TM-catalyzed conjugate arylation reactions of activated alkynes with arylboronic acids, and (3) TM-catalyzed aromatic C-H alkenylations with alkynes. This review surveys heterocycle synthesis via TM-catalyzed hydroarylation of alkynes according to the above classification, with an emphasis on the scope and limitations, as well as the underlying mechanisms.

  8. Pd-Catalyzed C-H activation/oxidative cyclization of acetanilide with norbornene: concise access to functionalized indolines.

    Science.gov (United States)

    Gao, Yang; Huang, Yubing; Wu, Wanqing; Huang, Kefan; Jiang, Huanfeng

    2014-08-07

    An efficient Pd-catalyzed oxidative cyclization reaction for the synthesis of functionalized indolines by direct C-H activation of acetanilide has been developed. The norbornylpalladium species formed via direct ortho C-H activation of acetanilides is supposed to be a key intermediate in this transformation.

  9. Chloride-catalyzed corrosion of plutonium in glovebox atmospheres

    International Nuclear Information System (INIS)

    Burgess, M.; Haschke, J.M.; Allen, T.H.; Morales, L.A.; Jarboe, D.M.; Puglisi, C.V.

    1998-04-01

    Characterization of glovebox atmospheres and the black reaction product formed on plutonium surfaces shows that the abnormally rapid corrosion of components in the fabrication line is consistent with a complex salt-catalyzed reaction involving gaseous hydrogen chloride (HCl) and water. Analytical data verify that chlorocarbon and HCl vapors are presented in stagnant glovebox atmospheres. Hydrogen chloride concentrations approach 7 ppm at some locations in the glovebox line. The black corrosion product is identified as plutonium monoxide monohydride (PuOH), a product formed by hydrolysis of plutonium in liquid water and salt solutions at room temperature. Plutonium trichloride (PuCl 3 ) produced by reaction of HCl at the metal surface is deliquescent and apparently forms a highly concentrated salt solution by absorbing moisture from the glovebox atmosphere. Rapid corrosion is attributed to the ensuing salt-catalyzed reaction between plutonium and water. Experimental results are discussed, possible involvement of hydrogen fluoride (HF) is examined, and methods of corrective action are presented in this report

  10. Improvements on enzymatic hydrolysis of human hair for illicit drug determination by gas chromatography/mass spectrometry.

    Science.gov (United States)

    Míguez-Framil, Martha; Moreda-Piñeiro, Antonio; Bermejo-Barrera, Pilar; López, Patricia; Tabernero, María Jesús; Bermejo, Ana María

    2007-11-15

    The use of ultrasound energy for accelerating the pronase E enzymatic hydrolysis of human hair for extracting illicit drugs has been novelty tested. The enzymatic extracts obtained after 30 min of sonication in an ultrasonic water bath were subjected to an optimized solid-phase extraction process, which involved a solution of 2.0% (v/v) acetic acid in methanol as eluting solution and concentration by N2 stream evaporation. A gas chromatography/mass spectrometry method was used to separate and determine cocaine, benzoylecgonine, codeine, morphine, and 6-monoacethylmorphine in 20 min. Variables affecting ultrasound-assisted pronase E hydrolysis such as hydrolysis temperature, hydrolysis time, enzyme concentration, catalyzer (1,4-dithiothreitol) concentration, ionic strength, pH, and ultrasound frequency were simultaneously evaluated by a Plackett-Burman design 2(8) PBD of resolution III. The most statistically significant variables were ionic strength and pH, which means that analyte extraction is mainly attributed to pronase E activity. The optimization or evaluation of all the factors has led to an accelerated pronase E hydrolysis of human hair, which can be completed in 30 min. Results have been found to be statistically similar to those obtained with conventional pronase E hydrolysis. The accelerated method was finally applied to several human hair samples from multidrug abusers.

  11. Hydrolysis of lactose with -D-galactosidase

    Directory of Open Access Journals (Sweden)

    Vesna Stehlik-Tomas

    2001-06-01

    Full Text Available The conditions of lactose hydrolysis with enzyme preparation of D-galactosidase were investigated. The aim of this work was to considered the use of whey in fermentative processes with yeast Saccharomyces cerevisiae. Enzymatic hydrolysis was conducted at different temperatures, with different lactose concentrations in medium and different concentrations of added enzyme. The results show that optimal temperature for hydrolysis was 40°C. The optimal amount of enzyme preparation was 2 gL-1 in lactose medium with 5-10 % lactose.

  12. Effect of hydrolysis enzymatic process of corn using protease crude (Rhizopus oligosporus-C1) to produce corn hydrolisate rich folic acid

    Science.gov (United States)

    Maryati, Yati; Susilowati, Agustine; Melanie, Hakiki; Lotulung, Puspa D.

    2017-11-01

    Corn hydrolyzate (Zea mays L) as a functional food fortificant derived from natural folic acid has been evaluated through a hydrolysis process using protease enzyme Rhizopus oligosporus strain C1. Enzymatic hydrolysis was carried out on two types of corn; yellow and white pearl variety corn, at concentration of protease enzyme (rough) 0.025; 0.125; and 0.225% (v/w of soluble nixtamal corn protein) with a hydrolysis time of 24 h at 30 °C, and pH 5.0. The results showed that the concentration of protease enzymes can increase the folic acid to the optimum condition, from the beginning to the end of the process time. Folic acid optimization of hydrolysis results in each corn was at the concentration of protease enzyme 0.225% (v/w of soluble nixtamal corn protein) in white corn and yellow corn at 24 hours hydrolysis, with folic acid composition, 283.56 µg/mL and 412.52 µg/mL, 1.07 and 1.04 mg/mL of soluble proteins, proteolytic activity 2.09 and 2.06 U/mL, total solids of 21.74 and 17.85%, total sugars of 0.56 and 2.22 mg/mL, and reducing sugar 91.72 and 48.47 mg/mL. In this condition, the increase of optimum folic acid for white corn was 33.57% and for yellow corn was 71.60% after hydrolysis.

  13. Production of alkyl esters from macaw palm oil by a sequential hydrolysis/esterification process using heterogeneous biocatalysts: optimization by response surface methodology.

    Science.gov (United States)

    Bressani, Ana Paula P; Garcia, Karen C A; Hirata, Daniela B; Mendes, Adriano A

    2015-02-01

    The present study deals with the enzymatic synthesis of alkyl esters with emollient properties by a sequential hydrolysis/esterification process (hydroesterification) using unrefined macaw palm oil from pulp seeds (MPPO) as feedstock. Crude enzymatic extract from dormant castor bean seeds was used as biocatalyst in the production of free fatty acids (FFA) by hydrolysis of MPPO. Esterification of purified FFA with several alcohols in heptane medium was catalyzed by immobilized Thermomyces lanuginosus lipase (TLL) on poly-hydroxybutyrate (PHB) particles. Under optimal experimental conditions (mass ratio oil:buffer of 35% m/m, reaction temperature of 35 °C, biocatalyst concentration of 6% m/m, and stirring speed of 1,000 rpm), complete hydrolysis of MPPO was reached after 110 min of reaction. Maximum ester conversion percentage of 92.4 ± 0.4% was reached using hexanol as acyl acceptor at 750 mM of each reactant after 15 min of reaction. The biocatalyst retained full activity after eight successive cycles of esterification reaction. These results show that the proposed process is a promising strategy for the synthesis of alkyl esters of industrial interest from macaw palm oil, an attractive option for the Brazilian oleochemical industry.

  14. Morphological transitions of brain sphingomyelin are determined by the hydration protocol: ripples re-arrange in plane, and sponge-like networks disintegrate into small vesicles.

    Science.gov (United States)

    Meyer, H W; Bunjes, H; Ulrich, A S

    1999-06-01

    The phase transition of hydrated brain sphingomyelin occurs at around 35 degrees C, which is close to the physiological temperature. Freeze-fracture electron microscopy is used to characterize different gel state morphologies in terms of solid-ordered and liquid-ordered phase states, according to the occurrence of ripples and other higher-dimensional bilayer deformations. Evidently, the natural mixed-chain sphingomyelin does not assume the flat L beta, phase but instead the rippled P beta, phase, with symmetric and asymmetric ripples as well as macroripples and an egg-carton pattern, depending on the incubation conditions. An unexpected difference was observed between samples that are hydrated above and below the phase transition temperature. When the lipid is hydrated at low temperature, a sponge-like network of bilayers is formed in the gel state, next to some normal lamellae. The network loses its ripples during cold-incubation, which indicates the formation of a liquid-ordered (lo) gel phase. Ripples re-appear upon warming and the sponge-like network disintegrates spontaneously and irreversibly into small vesicles above the phase transition.

  15. Bioreversible Derivatives of Phenol. 2. Reactivity of Carbonate Esters with Fatty Acid-like Structures Towards Hydrolysis in Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Claus Larsen

    2007-10-01

    Full Text Available A series of model phenol carbonate ester prodrugs encompassing derivatives with fatty acid-like structures were synthesized and their stability as a function of pH (range 0.4 – 12.5 at 37°C in aqueous buffer solutions investigated. The hydrolysis rates in aqueous solutions differed widely, depending on the selected pro-moieties (alkyl and aryl substituents. The observed reactivity differences could be rationalized by the inductive and steric properties of the substituent groups when taking into account that the mechanism of hydrolysis may change when the type of pro-moiety is altered, e.g. n-alkyl vs. t-butyl. Hydrolysis of the phenolic carbonate ester 2-(phenoxycarbonyloxy-acetic acid was increased due to intramolecular catalysis, as compared to the derivatives synthesized from ω-hydroxy carboxylic acids with longer alkyl chains. The carbonate esters appear to be less reactive towards specific acid and base catalyzed hydrolysis than phenyl acetate. The results underline that it is unrealistic to expect that phenolic carbonate ester prodrugs can be utilized in ready to use aqueous formulations. The stability of the carbonate ester derivatives with fatty acid-like structures, expected to interact with the plasma protein human serum albumin, proved sufficient for further in vitro and in vivo evaluation of the potential of utilizing HSA binding in combination with the prodrug approach for optimization of drug pharmacokinetics.

  16. Polysiloxanes derived from the controlled hydrolysis of tetraethoxysilane as precursors to silica for use in ceramic processing

    Science.gov (United States)

    Philipp, Warren H.

    1990-01-01

    Synthesis, properties, and potential applications in ceramic processing for two polysiloxane silica precursors derived from the controlled hydrolysis of tetraethoxysilane (TEOS) are presented. The higher molecular weight TEOS-A is a thick adhesive liquid of viscosity 8000 to 12,000 c.p. having a SiO2 char yield of about 55 percent. The lower molecular weight TEOS-B is a more fluid liquid of viscosity 150 to 200 c.p. having a SiO2 char yield of about 52 percent. The acid catalyzed hydrolysis of TEOS to hydrated silica gel goes through a series of polysiloxane intermediates. The rate of this transition increases with the quantity of water added to the TEOS; thus, for ease of polymer isolation, the amount of water added must be carefully determined so as to produce the desired polymer in a reasonable time. The water to TEOS mole ratio falls in the narrow range of 1.05 for TEOS-A and 0.99 for TEOS-B. Further polymerization or gelation is prevented by storing at -5 C in a freezer. Both polysiloxanes thermoset to a glassy solid at 115 C. The liquid polymers are organic in nature in that they are miscible with toluene and ethanol, slightly souble in heptane, but immiscible with water. For both polymers, results on viscosity versus time are given at several temperatures and water additions. Based on these results, some examples of practical utilization of the precursors for ceramic fabrication are given.

  17. Nickel-Catalyzed C sp2 –C sp3 Cross-Coupling via C–O Bond Activation

    KAUST Repository

    Guo, Lin

    2016-06-13

    A new and efficient nickel-catalyzed alkylation of CAr-O electrophiles with B-alkyl-9-BBNs is described. The transformation is characterized by its functional group tolerance and provides a practical and versatile access to various Csp2-Csp3 bonds through Csp2-O substitution, without the restriction of β-hydride elimination. Moreover, the advantage of the newly developed method was demonstrated in a selective and sequential C-O bond activation process. © 2016 American Chemical Society.

  18. Lipase Catalyzed Kinetic Resolution of rac-2-(3-Methoxy-4-methylphenyl) propan-1-ol and rac-2-(3-Hydroxy-4-methylphenyl)propyl propanoate for S-(+)-Xanthorrhizol

    International Nuclear Information System (INIS)

    Shafioul, Azam Sharif Mohammed; Cheong, Chan Seong

    2012-01-01

    Xanthorrhizol is a bisabolane type of natural sesquiterpene, the major component of essential oils of Curcuma xanthorrhiza. 2-(3-Methoxy-4-methylphenyl)propan-1-ol and 2-(3-hydroxy-4-methyl phenyl)propan-1-ol could be essential building block for enantioselective synthesis of xanthorrhizol. Enantioselective (c = 53%, E = 80 ± 3) for R-(+)-2-(3-hydroxy-4-methylphenyl) propan-1-ol and (c = 58%, E = 27 ± 1) for R-(+)-2-(3- methoxy-4-methylphenyl) propan-1-ol resolution processes were developed via lipase-catalyzed reaction. We found lipase Aspergillus oryzae (AOL) and Porcine pancreas (PPL) are selective to transesterification and hydrolysis in organic and aqueous phase. Modified demethylated substrate is appropriate for enantioselective hydrolysis reaction without any additives. Enantiopure chiral alcohol was crystallized from ethyl acetate/ n-hexane co-solvent system. Gram scale resolved chiral intermediate will facilitate the synthesis of the unnatural S-(+)-xanthorrhizol, the corresponding isomer of the natural one

  19. Lipase Catalyzed Kinetic Resolution of rac-2-(3-Methoxy-4-methylphenyl) propan-1-ol and rac-2-(3-Hydroxy-4-methylphenyl)propyl propanoate for S-(+)-Xanthorrhizol

    Energy Technology Data Exchange (ETDEWEB)

    Shafioul, Azam Sharif Mohammed [University of Science and Technology, Daejeon (Korea, Republic of); Cheong, Chan Seong [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2012-02-15

    Xanthorrhizol is a bisabolane type of natural sesquiterpene, the major component of essential oils of Curcuma xanthorrhiza. 2-(3-Methoxy-4-methylphenyl)propan-1-ol and 2-(3-hydroxy-4-methyl phenyl)propan-1-ol could be essential building block for enantioselective synthesis of xanthorrhizol. Enantioselective (c = 53%, E = 80 ± 3) for R-(+)-2-(3-hydroxy-4-methylphenyl) propan-1-ol and (c = 58%, E = 27 ± 1) for R-(+)-2-(3- methoxy-4-methylphenyl) propan-1-ol resolution processes were developed via lipase-catalyzed reaction. We found lipase Aspergillus oryzae (AOL) and Porcine pancreas (PPL) are selective to transesterification and hydrolysis in organic and aqueous phase. Modified demethylated substrate is appropriate for enantioselective hydrolysis reaction without any additives. Enantiopure chiral alcohol was crystallized from ethyl acetate/ n-hexane co-solvent system. Gram scale resolved chiral intermediate will facilitate the synthesis of the unnatural S-(+)-xanthorrhizol, the corresponding isomer of the natural one.

  20. Enzymatic Hydrolysis of Wheat Arabinoxylan by a Recombinant "Minimal" Enzyme Cocktail Containing beta-Xylosidase and Novel endo-1,4-beta-Xylanase and alpha-L-Arabinofuranosidase Activities

    DEFF Research Database (Denmark)

    Sørensen, Hanne R.; Pedersen, Sven; Jørgensen, Christel T.

    2007-01-01

    24 h at pH 5, 50 degrees C. A 10%:40%:50% mixture of Abf II, Abf III, and beta-xyl released 56 mg of arabinose and 91 mg of xylose per gram of vinasse dry matter after 24 h at pH 5, 50 degrees C. The optimal dosages of the "minimal" enzyme cocktails were determined to be 0.4, 0.3, and 0.2 g enzyme......This study describes the identification of the key enzyme activities required in a "minimal" enzyme cocktail able to catalyze hydrolysis of water-soluble and water-insoluble wheat arabinoxylan and whole vinasse, a fermentation effluent resulting from industrial ethanol manufacture from wheat...

  1. Hydrolysis, formation and ionization constants at 250C, and at high temperature-high ionic strength

    International Nuclear Information System (INIS)

    Phillips, S.L.; Phillips, C.A.; Skeen, J.

    1985-02-01

    Thermochemical data for nuclear waste disposal are compiled. The resulting computerized database consists of critically evaluated data on Gibbs energy of formation, enthalpy of formation, entropy and heat capacity of selected substances for about 16 elements at 25 0 C and zero ionic strength. Elements covered are Am, As, Br, C, Cl, F, I, Mo, Np, N, O, P, Pu, Si, Sr, S, and U. Values of these thermodynamic properties were used to calculate equilibrium quotients for hydrolysis, complexation and ionization reactions up to 300 0 C and 3 ionic strength, for selected chemical reactions

  2. Enzymatic Hydrolysis of Alkaline Pretreated Coconut Coir

    Directory of Open Access Journals (Sweden)

    Akbarningrum Fatmawati

    2013-06-01

    Full Text Available The purpose of this research is to study the effect of concentration and temperature on the cellulose and lignin content, and the reducing sugars produced in the enzymatic hydrolysis of coconut coir. In this research, the coconut coir is pretreated using 3%, 7%, and 11% NaOH solution at 60oC, 80oC, and 100oC. The pretreated coir were assayed by measuring the amount of cellulose and lignin and then hydrolysed using Celluclast and Novozyme 188 under various temperature (30oC, 40oC, 50oC and pH (3, 4, 5. The hydrolysis results were assayed for the reducing sugar content. The results showed that the alkaline delignification was effective to reduce lignin and to increase the cellulose content of the coir. The best delignification condition was observed at 11% NaOH solution and 100oC which removed 14,53% of lignin and increased the cellulose content up to 50,23%. The best condition of the enzymatic hydrolysis was obtained at 50oC and pH 4 which produced 7,57 gr/L reducing sugar. © 2013 BCREC UNDIP. All rights reservedReceived: 2nd October 2012; Revised: 31st January 2013; Accepted: 6th February 2013[How to Cite: Fatmawati, A., Agustriyanto, R., Liasari, Y. (2013. Enzymatic Hydrolysis of Alkaline Pre-treated Coconut Coir. Bulletin of Chemical Reaction Engineering & Catalysis, 8 (1: 34-39 (doi:10.9767/bcrec.8.1.4048.34-39[Permalink/DOI: http://dx.doi.org/10.9767/bcrec.8.1.4048.34-39] | View in  |

  3. Oxidant-free Rh(III)-catalyzed direct C-H olefination of arenes with allyl acetates.

    Science.gov (United States)

    Feng, Chao; Feng, Daming; Loh, Teck-Peng

    2013-07-19

    Rh(III)-catalyzed direct olefination of arenes with allyl acetate via C-H bond activation is described using N,N-disubstituted aminocarbonyl as the directing group. The catalyst undergoes a redox neutral process, and high to excellent yields of trans-products are obtained. This protocol exhibits a wide spectrum of functionality compatibility because of the simple reaction conditions employed and provides a highly effective synthetic method in the realm of C-H olefination.

  4. Polymeric amylase nanoparticles as a new semi-synthetic enzyme system for hydrolysis of starch.

    Science.gov (United States)

    Say, R; Şenay, R Hilal; Biçen, Özlem; Ersöz, Arzu; Şişman Yılmaz, Filiz; Akgöl, Sinan; Denizli, Adil

    2013-05-01

    α-Amylase (EC 3.2.1.1; α-D-1,4,glucan glucanohydrolase) catalyzes the hydrolysis of α-D-(1,4)-glucosidic linkages in starch, glycogen, and various malto-oligosaccharides, by releasing α-anomeric products. In this study, a novel method has been developed to prepare nanoprotein particles that carry α-amylase as a monomer by using a photosensitive microemulsion polymerization process. The nanostructured α-amylase with photosensitive features have been characterized by fluorescence spectroscopy, transmission electron microscopy (TEM) and Zeta Sizer. The fluorescence intensity of amylase nanoparticles was determined to be 658 a.u. at 610 nm and the average particle size of nanoamylase was found to be about 71.8 nm. Both free α-amylase and nanoparticles were used in the hydrolysis of starch under varying reaction conditions such as pH and temperature that affect enzyme activity and the results were compared to each other. Km values were 0.26 and 0.87 mM and Vmax values were 0.36 IU mg(-1) and 22.32 IU mg(-1) for nanoenzyme and free enzyme, respectively. Then, thermal stability, storage stability and reusability were investigated and according to the results, activity was preserved 60% at 60 °C; 20% at 70-80 °C temperature values and 80% after 105 days storage. Finally after 10 cycles, the activity was preserved 90% and this novel enzymatic polymeric amylase nanoparticle has showed considerable potential as reusable catalyst. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Phase Behavior and Domain Size in Sphingomyelin-Containing Lipid Bilayers

    Science.gov (United States)

    Petruzielo, Robin S.; Heberle, Frederick A.; Drazba, Paul; Katsaras, John; Feigenson, Gerald W.

    2013-01-01

    Membrane raft size measurements are crucial to understanding the stability and functionality of rafts in cells. The challenge of accurately measuring raft size is evidenced by the disparate reports of domain sizes, which range from nanometers to microns for the ternary model membrane system sphingomyelin (SM)/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/cholesterol (Chol). Using Förster resonance energy transfer (FRET) and differential scanning calorimetry (DSC), we established phase diagrams for porcine brain SM (bSM)/dioleoyl-sn-glycero-3-phosphocholine (DOPC)/Chol and bSM/POPC/Chol at 15 and 25°C. By combining two techniques with different spatial sensitivities, namely FRET and small-angle neutron scattering (SANS), we have significantly narrowed the uncertainty in domain size estimates for bSM/POPC/Chol mixtures. Compositional trends in FRET data revealed coexisting domains at 15 and 25°C for both mixtures, while SANS measurements detected no domain formation for bSM/POPC/Chol. Together these results indicate that liquid domains in bSM/POPC/Chol are between 2 and 7 nm in radius at 25°C: that is, domains must be on the order of the 2–6 nm Förster distance of the FRET probes, but smaller than the ~7 nm minimum cluster size detectable with SANS. However, for palmitoyl SM (PSM)/POPC/Chol at a similar composition, SANS detected coexisting liquid domains. This increase in domain size upon replacing the natural SM component (which consists of a mixture of chain lengths) with synthetic PSM, suggests a role for SM chain length in modulating raft size in vivo. PMID:23337475

  6. Development of C-reactive protein certified reference material NMIJ CRM 6201-b: optimization of a hydrolysis process to improve the accuracy of amino acid analysis.

    Science.gov (United States)

    Kato, Megumi; Kinumi, Tomoya; Yoshioka, Mariko; Goto, Mari; Fujii, Shin-Ichiro; Takatsu, Akiko

    2015-04-01

    To standardize C-reactive protein (CRP) assays, the National Metrology Institute of Japan (NMIJ) has developed a C-reactive protein solution certified reference material, CRM 6201-b, which is intended for use as a primary reference material to enable the SI-traceable measurement of CRP. This study describes the development process of CRM 6201-b. As a candidate material of the CRM, recombinant human CRP solution was selected because of its higher purity and homogeneity than the purified material from human serum. Gel filtration chromatography was used to examine the homogeneity and stability of the present CRM. The total protein concentration of CRP in the present CRM was determined by amino acid analysis coupled to isotope-dilution mass spectrometry (IDMS-AAA). To improve the accuracy of IDMS-AAA, we optimized the hydrolysis process by examining the effect of parameters such as the volume of protein samples taken for hydrolysis, the procedure of sample preparation prior to the hydrolysis, hydrolysis temperature, and hydrolysis time. Under optimized conditions, we conducted two independent approaches in which the following independent hydrolysis and liquid chromatography-isotope dilution mass spectrometry (LC-IDMS) were combined: one was vapor-phase acid hydrolysis (130 °C, 24 h) and hydrophilic interaction liquid chromatography-mass spectrometry (HILIC-MS) method, and the other was microwave-assisted liquid-phase acid hydrolysis (150 °C, 3 h) and pre-column derivatization liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. The quantitative values of the two different amino acid analyses were in agreement within their uncertainties. The certified value was the weighted mean of the results of the two methods. Uncertainties from the value-assignment method, between-method variance, homogeneity, long-term stability, and short-term stability were taken into account in evaluating the uncertainty for a certified value. The certified value and the

  7. Mild Palladium Catalyzed ortho C-H Bond Functionalizations of Aniline Derivatives.

    Science.gov (United States)

    Tischler, Ms Orsolya; Tóth, Mr Balázs; Novák, Zoltán

    2017-02-01

    This account collects the developments and transformations which avoid the utilization of harsh reaction conditions in the field of palladium catalyzed, ortho-directed C-H activation of aniline derivatives from the first attempts to up-to-date results, including the results of our research laboratory. The discussed functionalizations performed under mild conditions include acylation, olefination, arylation, alkylation, alkoxylation reactions. Beside the optimization studies and the synthetic applications mechanistic investigations are also presented. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Hydrolysis reactor for hydrogen production

    Science.gov (United States)

    Davis, Thomas A.; Matthews, Michael A.

    2012-12-04

    In accordance with certain embodiments of the present disclosure, a method for hydrolysis of a chemical hydride is provided. The method includes adding a chemical hydride to a reaction chamber and exposing the chemical hydride in the reaction chamber to a temperature of at least about 100.degree. C. in the presence of water and in the absence of an acid or a heterogeneous catalyst, wherein the chemical hydride undergoes hydrolysis to form hydrogen gas and a byproduct material.

  9. Palladium-Catalyzed ortho C-H Arylation of Benzaldehydes Using ortho-Sulfinyl Aniline Transient Auxiliary.

    Science.gov (United States)

    Mu, Delong; He, Gang; Chen, Gong

    2018-05-03

    A PdII-catalyzed ortho-(Csp2)-H arylation reaction of benzaldehydes using catalytic amount of 2-methylsulfinyl-aniline as transient auxiliary was developed. This reaction is compatible with a broad range of benzaldehyde and aryl iodide substrates. Compared with other related reaction systems, an excellent regioselectivity for ortho-C(sp2)-H bonds over benzylic C(sp3)-H bonds was obtained for ortho-alkyl-benzaldehyde substrates. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Palladium(II)-catalyzed ortho-C-H arylation/alkylation of N-benzoyl α-amino ester derivatives.

    Science.gov (United States)

    Misal Castro, Luis C; Chatani, Naoto

    2014-04-14

    The palladium-catalyzed arylation/alkylation of ortho-C-H bonds in N-benzoyl α-amino ester derivatives is described. In such a system both the NH-amido and the CO2R groups in the α-amino ester moieties play a role in successful C-H activation/C-C bond formation using iodoaryl coupling partners. A wide variety of functional groups and electron-rich/deficient iodoarenes are tolerated. The yields obtained range from 20 to 95%. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Palladium-catalyzed domino C,N-coupling/carbonylation/Suzuki coupling reaction: an efficient synthesis of 2-aroyl-/heteroaroylindoles.

    Science.gov (United States)

    Arthuis, Martin; Pontikis, Renée; Florent, Jean-Claude

    2009-10-15

    A convenient one-pot synthesis of 2-aroylindoles using a domino palladium-catalyzed C,N-coupling/carbonylation/C,C-coupling sequence is described. The reaction involved easily prepared 2-gem-dibromovinylanilines and boronic acids under carbon monoxide. Optimized reaction conditions allowed the construction of a wide variety of highly functionalized 2-aroyl-/heteroaroylindoles in satisfactory yields.

  12. Cobalt-catalyzed, aminoquinoline-directed C(sp²)-H bond alkenylation by alkynes.

    Science.gov (United States)

    Grigorjeva, Liene; Daugulis, Olafs

    2014-09-15

    A method for cobalt-catalyzed, aminoquinoline- and picolinamide-directed C(sp(2))-H bond alkenylation by alkynes was developed. The method shows excellent functional-group tolerance and both internal and terminal alkynes are competent substrates for the coupling. The reaction employs a Co(OAc)2⋅4 H2O catalyst, Mn(OAc)2 co-catalyst, and oxygen (from air) as a terminal oxidant. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Enhanced functional properties of tannic acid after thermal hydrolysis

    Science.gov (United States)

    Thermal hydrolysis processing of fresh tannic acid was carried out in a closed reactor at four different temperatures (65, 100, 150 and 200°C). Pressures reached in the system were 1.3 and 4.8 MPa at 150 and 200°C, respectively. Hydrolysis products (gallic acid and pyrogallol) were separated and qua...

  14. Hydrolysis of corn oil using subcritical water

    Directory of Open Access Journals (Sweden)

    Pinto Jair Sebastião S.

    2006-01-01

    Full Text Available This work presents the results of a study on the use of subcritical water as both solvent and reactant for the hydrolysis of corn oil without the use of acids or alkalis at temperatures of 150-280 degreesC. Corn oil hydrolysis leads to the formation of its respective fatty acids with the same efficiency of conventional methods. Fatty acids form an important group of products, which are used in a range of applications. The confirmation and identification of the hydrolysis products was done by HT-HRGC-FID and HRGC/MS.

  15. HYDROLYSIS OF CHEESEWHEY PROTEINSWITH TRYPSIN, CHYMOTRYPSINAND CARBOXYPEPTIDASEA

    Directory of Open Access Journals (Sweden)

    M. F. CUSTÓDIO

    2009-01-01

    Full Text Available

    This work presents a method for adding value to cheese whey residues by whey proteins hydrolysis, using trypsin, chymotrypsin and carboxypeptidase A as catalysts. Sweet cheese whey was dialyzed and filtered in kaolin. Lactose and protein contents were analyzed after each step. The activities of bovine pancreas trypsin and chymotrypsin were measured at different pHs and temperatures. The optimal pH for the hydrolysis of whey proteins was 9.0 for both enzymes. Optima temperatures were 60ºC for trypsin, and 50ºC for chymotrypsin. Trypsin exhibited typical Michaelis-Menten behavior, but chymotrypsin did not. Electrophoretic analysis showed that neither trypsin nor chymotrypsin alone hydrolyzed whey proteins in less than three hours. Hydrolysis rates of -lactalbumin by trypsin, and of bovine serum albumin by chymotrypsin were low. When these enzymes were combined, however, all protein fractions were attacked and rates of hydrolysis were enhanced by one order of magnitude. The addition of carboxypeptidase A to the others enzymes did not improve the process yield.

  16. Synthesis of heterocyclic compounds through palladium-catalyzed C-H cyclization processes.

    Science.gov (United States)

    Inamoto, Kiyofumi

    2013-01-01

    Herein, we describe our development of synthetic methods for heterocyclic compounds based on the palladium-catalyzed carbon-hydrogen bond (C-H) functionalization/intramolecular carbon-heteroatom (nitrogen or sulfur) bond formation process. By this C-H cyclization method, we efficiently prepared various N-heterocycles, including indazoles, indoles, and 2-quinolinones, as well as S-heterocycles such as benzothiazoles and benzo[b]thiophenes. Yields are typically good to high and good functional-group tolerance is observed for each process, thereby indicating that the method provides a novel, highly applicable synthetic route to the abovementioned biologically important heterocyclic frameworks. As an application of this approach, an auto-tandem-type, one-pot process involving the oxidative Heck reaction and subsequent C-H cyclization using cinnamamides and arylboronic acids as starting materials in the presence of a palladium catalyst was also developed for the rapid construction of the 2-quinolinone nucleus.

  17. Enzymatic hydrolysis of pretreated soybean straw

    International Nuclear Information System (INIS)

    Xu Zhong; Wang Qunhui; Jiang Zhaohua; Yang Xuexin; Ji Yongzhen

    2007-01-01

    In order to produce lactic acid, from agricultural residues such as soybean straw, which is a raw material for biodegradable plastic production, it is necessary to decompose the soybean straw into soluble sugars. Enzymatic hydrolysis is one of the methods in common use, while pretreatment is the effective way to increase the hydrolysis rate. The optimal conditions of pretreatment using ammonia and enzymatic hydrolysis of soybean straw were determined. Compared with the untreated straw, cellulose in straw pretreated by ammonia liquor (10%) soaking for 24 h at room temperature increased 70.27%, whereas hemicellulose and lignin in pretreated straw decreased to 41.45% and 30.16%, respectively. The results of infrared spectra (IR), scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis also showed that the structure and the surface of the straw were changed through pretreatment that is in favor of the following enzymatic hydrolysis. maximum enzymatic hydrolysis rate of 51.22% was achieved at a substrate concentration of 5% (w/v) at 50 deg. C and pH 4.8 using cellulase (50 fpu/g of substrate) for 36 h

  18. Isolation of plasma membranes from cultured glioma cells and application to evaluation of membrane sphingomyelin turnover

    International Nuclear Information System (INIS)

    Cook, H.W.; Palmer, F.B.; Byers, D.M.; Spence, M.W.

    1988-01-01

    A rapid and reliable method for the isolation of plasma membranes and microsomes of high purity and yield from cultured glioma cells is described. The procedure involves disruption by N2 cavitation, preliminary separation by centrifugation in Tricine buffer, and final separation on a gradient formed from 40% Percoll at pH 9.3. Enzyme and chemical markers indicated greater than 60% yield with six- to eightfold enrichment for plasma membranes and greater than 25% yield with three- to fourfold enrichment for a microsomal fraction consisting mainly of endoplasmic reticulum. The final fractions were obtained with high reproducibility in less than 1 h from the time of cell harvesting. Application of this procedure to human fibroblasts in culture is assessed. The isolation procedure was applied to investigations of synthesis and turnover of sphingomyelin and phosphatidylcholine in plasma membranes of glioma cells following incubation for 4-24 h with [methyl- 3 H]choline. These studies indicated that radioactivity from phosphatidylcholine synthesized in microsomes from exogenous choline may serve as a precursor of the head-group of sphingomyelin accumulating in the plasma membrane

  19. Expression of Trichoderma reesei β-mannanase in tobacco chloroplasts and its utilization in lignocellulosic woody biomass hydrolysis.

    Directory of Open Access Journals (Sweden)

    Pankaj Agrawal

    Full Text Available Lignocellulosic ethanol offers a promising alternative to conventional fossil fuels. One among the major limitations in the lignocellulosic biomass hydrolysis is unavailability of efficient and environmentally biomass degrading technologies. Plant-based production of these enzymes on large scale offers a cost-effective solution. Cellulases, hemicellulases including mannanases and other accessory enzymes are required for conversion of lignocellulosic biomass into fermentable sugars. β-mannanase catalyzes endo-hydrolysis of the mannan backbone, a major constituent of woody biomass. In this study, the man1 gene encoding β-mannanase was isolated from Trichoderma reesei and expressed via the chloroplast genome. PCR and Southern hybridization analysis confirmed site-specific transgene integration into the tobacco chloroplast genomes and homoplasmy. Transplastomic plants were fertile and set viable seeds. Germination of seeds in the selection medium showed inheritance of transgenes into the progeny without any Mendelian segregation. Expression of endo-β-mannanase for the first time in plants facilitated its characterization for use in enhanced lignocellulosic biomass hydrolysis. Gel diffusion assay for endo-β-mannanase showed the zone of clearance confirming functionality of chloroplast-derived mannanase. Endo-β-mannanase expression levels reached up to 25 units per gram of leaf (fresh weight. Chloroplast-derived mannanase had higher temperature stability (40 °C to 70 °C and wider pH optima (pH 3.0 to 7.0 than E.coli enzyme extracts. Plant crude extracts showed 6-7 fold higher enzyme activity than E.coli extracts due to the formation of disulfide bonds in chloroplasts, thereby facilitating their direct utilization in enzyme cocktails without any purification. Chloroplast-derived mannanase when added to the enzyme cocktail containing a combination of different plant-derived enzymes yielded 20% more glucose equivalents from pinewood than the

  20. Riccardin D-N induces lysosomal membrane permeabilization by inhibiting acid sphingomyelinase and interfering with sphingomyelin metabolism in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lin [Department of Natural Product Chemistry, Key Lab of Chemical Biology of MOE (Ministry of Education), Shandong University, Jinan 250012 (China); Niu, Huanmin [Department of Biochemistry and Molecular Biology, School of Medicine, Shandong University, Jinan 250012 (China); Sun, Bin [Department of Natural Product Chemistry, Key Lab of Chemical Biology of MOE (Ministry of Education), Shandong University, Jinan 250012 (China); Xiao, Yanan [School of Pharmaceutical Science, Shandong University, Jinan 250012 (China); Li, Wei [Department of Natural Product Chemistry, Key Lab of Chemical Biology of MOE (Ministry of Education), Shandong University, Jinan 250012 (China); Yuan, Huiqing [Department of Biochemistry and Molecular Biology, School of Medicine, Shandong University, Jinan 250012 (China); Lou, Hongxiang, E-mail: louhongxiang@sdu.edu.cn [Department of Natural Product Chemistry, Key Lab of Chemical Biology of MOE (Ministry of Education), Shandong University, Jinan 250012 (China)

    2016-11-01

    Lysosomes are important targets for anticancer drug discovery. Our previous study showed that Riccardin D-N (RD-N), a natural macrocylic bisbibenzyl derivative produced by Mannich reaction, induced cell death by accumulating in lysosomes. Experiments were performed on human lung squamous cell carcinoma tissue from left inferior lobar bronchus of patient xenografts and H460 cells. RD-N was administrated for 25 days. The specimens of xenografts in Balb/c athymic (nu +/nu +) male mice were removed for immunohistochemistry, subcellular fractionation, enzyme activities and Western blotting analysis. mRFP-GFP-LC3 reporter was used to examine autophagy in H460 cells. Sphingomyelin assay was evaluated by thin-layer chromatography and assay kit. Lysosomal membrane permeabilization (LMP) caused by acid sphingomyelinase (ASM) inhibition and subsequent changes of sphingomyelin (SM) metabolism selectively destabilized the cancer cell lysosomes in RD-N-treated H460 cells in vitro and tumor xenograft model in vivo. The destabilized lysosomes induced the release of cathepsins from the lysosomes into the cytosol and further triggered cell death. These results explain the underlying mechanism of RD-N induced LMP. It can be concluded that a more lysosomotropic derivative was synthesized by introduction of an amine group, which could have more potential applications in cancer therapy. - Highlights: • Riccardin D-N (RD-N) significantly downregulated LAMP1 expressions. • RD-N inhibited the acid sphingomyelinase activity. • RD-N induced lysosomal membrane permeabilization in vivo. • RD-N induced SM accumulation in the lysosomal membranes. • RD-N also induced the release of cathepsins from destabilized lysosomes.

  1. Riccardin D-N induces lysosomal membrane permeabilization by inhibiting acid sphingomyelinase and interfering with sphingomyelin metabolism in vivo

    International Nuclear Information System (INIS)

    Li, Lin; Niu, Huanmin; Sun, Bin; Xiao, Yanan; Li, Wei; Yuan, Huiqing; Lou, Hongxiang

    2016-01-01

    Lysosomes are important targets for anticancer drug discovery. Our previous study showed that Riccardin D-N (RD-N), a natural macrocylic bisbibenzyl derivative produced by Mannich reaction, induced cell death by accumulating in lysosomes. Experiments were performed on human lung squamous cell carcinoma tissue from left inferior lobar bronchus of patient xenografts and H460 cells. RD-N was administrated for 25 days. The specimens of xenografts in Balb/c athymic (nu +/nu +) male mice were removed for immunohistochemistry, subcellular fractionation, enzyme activities and Western blotting analysis. mRFP-GFP-LC3 reporter was used to examine autophagy in H460 cells. Sphingomyelin assay was evaluated by thin-layer chromatography and assay kit. Lysosomal membrane permeabilization (LMP) caused by acid sphingomyelinase (ASM) inhibition and subsequent changes of sphingomyelin (SM) metabolism selectively destabilized the cancer cell lysosomes in RD-N-treated H460 cells in vitro and tumor xenograft model in vivo. The destabilized lysosomes induced the release of cathepsins from the lysosomes into the cytosol and further triggered cell death. These results explain the underlying mechanism of RD-N induced LMP. It can be concluded that a more lysosomotropic derivative was synthesized by introduction of an amine group, which could have more potential applications in cancer therapy. - Highlights: • Riccardin D-N (RD-N) significantly downregulated LAMP1 expressions. • RD-N inhibited the acid sphingomyelinase activity. • RD-N induced lysosomal membrane permeabilization in vivo. • RD-N induced SM accumulation in the lysosomal membranes. • RD-N also induced the release of cathepsins from destabilized lysosomes.

  2. Probing the origins of catalytic discrimination between phosphate and sulfate monoester hydrolysis: comparative analysis of alkaline phosphatase and protein tyrosine phosphatases.

    Science.gov (United States)

    Andrews, Logan D; Zalatan, Jesse G; Herschlag, Daniel

    2014-11-04

    Catalytic promiscuity, the ability of enzymes to catalyze multiple reactions, provides an opportunity to gain a deeper understanding of the origins of catalysis and substrate specificity. Alkaline phosphatase (AP) catalyzes both phosphate and sulfate monoester hydrolysis reactions with a ∼10(10)-fold preference for phosphate monoester hydrolysis, despite the similarity between these reactions. The preponderance of formal positive charge in the AP active site, particularly from three divalent metal ions, was proposed to be responsible for this preference by providing stronger electrostatic interactions with the more negatively charged phosphoryl group versus the sulfuryl group. To test whether positively charged metal ions are required to achieve a high preference for the phosphate monoester hydrolysis reaction, the catalytic preference of three protein tyrosine phosphatases (PTPs), which do not contain metal ions, were measured. Their preferences ranged from 5 × 10(6) to 7 × 10(7), lower than that for AP but still substantial, indicating that metal ions and a high preponderance of formal positive charge within the active site are not required to achieve a strong catalytic preference for phosphate monoester over sulfate monoester hydrolysis. The observed ionic strength dependences of kcat/KM values for phosphate and sulfate monoester hydrolysis are steeper for the more highly charged phosphate ester with both AP and the PTP Stp1, following the dependence expected based on the charge difference of these two substrates. However, the dependences for AP were not greater than those of Stp1 and were rather shallow for both enzymes. These results suggest that overall electrostatics from formal positive charge within the active site is not the major driving force in distinguishing between these reactions and that substantial discrimination can be attained without metal ions. Thus, local properties of the active site, presumably including multiple positioned dipolar

  3. Asymmetric Brønsted acid-catalyzed aza-Diels–Alder reaction of cyclic C-acylimines with cyclopentadiene

    Directory of Open Access Journals (Sweden)

    Magnus Rueping

    2012-10-01

    Full Text Available A new chiral Brønsted acid-catalyzed aza-Diels–Alder reaction of cyclic C-acylimines with cyclopentadiene has been developed. The reaction provides optically active aza-tetracycles in good yields with high diastereo- and enantioselectivities under mild reaction conditions.

  4. DFT investigations of phosphotriesters hydrolysis in aqueous solution: a model for DNA single strand scission induced by N-nitrosoureas.

    Science.gov (United States)

    Liu, Tingting; Zhao, Lijiao; Zhong, Rugang

    2013-02-01

    DNA phosphotriester adducts are common alkylation products of DNA phosphodiester moiety induced by N-nitrosoureas. The 2-hydroxyethyl phosphotriester was reported to hydrolyze more rapidly than other alkyl phosphotriesters both in neutral and in alkaline conditions, which can cause DNA single strand scission. In this work, DFT calculations have been employed to map out the four lowest activation free-energy profiles for neutral and alkaline hydrolysis of triethyl phosphate (TEP) and diethyl 2-hydroxyethyl phosphate (DEHEP). All the hydrolysis pathways were illuminated to be stepwise involving an acyclic or cyclic phosphorane intermediate for TEP or DEHEP, respectively. The rate-limiting step for all the hydrolysis reactions was found to be the formation of phosphorane intermediate, with the exception of DEHEP hydrolysis in alkaline conditions that the decomposition process turned out to be the rate-limiting step, owing to the extraordinary low formation barrier of cyclic phosphorane intermediate catalyzed by hydroxide. The rate-limiting barriers obtained for the four reactions are all consistent with the available experimental information concerning the corresponding hydrolysis reactions of phosphotriesters. Our calculations performed on the phosphate triesters hydrolysis predict that the lower formation barriers of cyclic phosphorane intermediates compared to its acyclic counter-part should be the dominant factor governing the hydrolysis rate enhancement of DEHEP relative to TEP both in neutral and in alkaline conditions.

  5. An Efficient One-Pot Synthesis of Pyrano[3,2-c]quinolin-2,5-dione Derivatives Catalyzed by L-Proline

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2012-11-01

    Full Text Available A series of 4-aryl-6-methyl-3,4-dihydro-2H-pyrano[3,2-c]quinolin-2,5(6H-diones were synthesized via the three-component reactions of aromatic aldehydes, 4-hydroxy-1-methylquinolin-2(1H-one, and Meldrum’s acid catalyzed by L-proline. The structures of the products were identified by spectroscopic analysis. A mechanism for this three-component reaction catalyzed by L-proline was proposed.

  6. Mechanistic Study of the sPLA2 Mediated Hydrolysis of a Thio-ester Pro Anticancer Ether Lipid

    DEFF Research Database (Denmark)

    Linderoth, Lars; Fristrup, Peter; Hansen, Martin

    2009-01-01

    Secretory phospholipase A2 (sPLA2) is an interesting enzyme for triggered liposomal drug delivery to tumor tissue due the overexpression of sPLA2 in cancerous tissue. A drug delivery system based on the triggered release of therapeutics from sPLA2-sensitive liposomes constituted of pro anticancer...... ether lipids, which become cytotoxic upon sPLA2-catalyzed hydrolysis has previously been established. To optimize the hydrolysis rate of the lipids and thereby optimizing the release profile of the drugs from the liposomes, we have synthesized a thio-ester pro anticancer ether lipid. Liposomes...... constituted of this lipid showed an altered rate of hydrolysis by sPLA2. We have tested the cytotoxicity of the thio-ester pro anticancer ether lipids toward cancer cells, and the results showed that the cytotoxicity is indeed maintained upon sPLA2 exposure. To further understand the origin for the observed...

  7. Parameters affecting incorporation and by-product formation during the production of structured phospholipids by lipase-catalyzed acidolysis in solvent free system

    DEFF Research Database (Denmark)

    Vikbjerg, Anders Falk; Mu, Huiling; Xu, Xuebing

    2005-01-01

    By-product formation is a serious problem in the lipase-catalyzed acyl exchange of phospholipids (PL). By-products are formed due to parallel hydrolysis reactions and acyl migration in the reaction system. A clear elucidation of these side reactions is important for practical operation in order...... to minimize by-products during reaction. In the present study we examined the Lipozyme RM IM-catalyzed acidolysis for the production of structured phospholipids between phosphatidylcholine (PC) and caprylic acid in the solvent free system. A five-factor response surface design was used to evaluate...

  8. Kinetic study of hydrolysis of coconut fiber into glucose

    Science.gov (United States)

    Muhaimin, Sudiono, Sri

    2017-03-01

    Kinetic study of hydrolysis of coconut fiber into glucose has been done. The aim of this research was to study of the effect of time and temperature to the glucose as the result of the conversion of coconut fiber. The various temperature of the hydrolysis process were 30 °C, 48 °C, 72 °C and 95 °C and the various time of the hydrolysis process were 0, 15, 30, 60, 120, 180, 240, 300 minutes. A quantitative analysis was done by measured the concentration of the glucose as the result of the conversion of coconut fiber. The result showed that the rate constant from the various temperature were 3.10-4 minute-1; 8.10-4 minutees-1; 84.10-4 minute-1, and 205.10-4 minute-1, and the energy activation was 7,69. 103 kJ/mol.

  9. Molecular characterization and enzymatic hydrolysis of naringin extracted from kinnow peel waste.

    Science.gov (United States)

    Puri, Munish; Kaur, Aneet; Schwarz, Wolfgang H; Singh, Satbir; Kennedy, J F

    2011-01-01

    Kinnow peel, a waste rich in glycosylated phenolic substances, is the principal by-product of the citrus fruit processing industry and its disposal is becoming a major problem. This peel is rich in naringin and may be used for rhamnose production by utilizing α-L-rhamnosidase (EC 3.2.1.40), an enzyme that catalyzes the cleavage of terminal rhamnosyl groups from naringin to yield prunin and rhamnose. In this work, infrared (IR) spectroscopy confirmed molecular characteristics of naringin extracted from kinnow peel waste. Further, recombinant α-L-rhamnosidase purified from Escherichia coli cells using immobilized metal-chelate affinity chromatography (IMAC) was used for naringin hydrolysis. The purified enzyme was inhibited by Hg2+ (1 mM), 4-hydroxymercuribenzoate (0.1 mM) and cyanamide (0.1 mM). The purified enzyme established hydrolysis of naringin extracted from kinnow peel and thus endorses its industrial applicability for producing rhamnose. Copyright © 2010 Elsevier B.V. All rights reserved.

  10. Synthesis and Characterization of Si Oxide Coated Nano Ceria by Hydrolysis, and Hydrothermal Treatment at Low Temperature

    Directory of Open Access Journals (Sweden)

    Kong M.

    2017-06-01

    Full Text Available The purpose of this work was to the application of Si oxide coatings. This study deals with the preparation of ceria (CeO2 nanoparticles coating with SiO2 by water glass and hydrolysis reaction. First, the low temperature hydro-reactions were carried out at 30~100°C. Second, Silicon oxide-coated Nano compounds were obtained by the catalyzing synthesis. CeO2 Nano-powders have been successfully synthesized by means of the hydrothermal method, in a low temperature range of 100~200°C. In order to investigate the structure and morphology of the Nano-powders, scanning electron microscopy (SEM and X-ray diffraction (XRD were employed. The XRD results revealed the amorphous nature of silica nanoparticles. To analyze the quantity and properties of the compounds coated with Si oxide, transmission electron microscopy (TEM in conjunction with electron dispersive spectroscopy was used. Finally, it is suggested that the simple growth process is more favorable mechanism than the solution/aggregation process.

  11. Combined enzymatic hydrolysis and fermentation of hemicellulose to 2,3-butanediol

    Energy Technology Data Exchange (ETDEWEB)

    Yu, E.K.C.; Deschatelets, L.; Saddler, J.N.

    1984-06-01

    Hemicellulose-rich fractions from several agricultural residues were converted to 2,3-butanediol by a combined enzymatic hydrolysis and fermentation process. Culture filtrates from Trichoderma harzianum E58 were used to hydrolyze the substrates while Klebsiella pneumoniae fermented the liberated sugars to 2,3-butanediol. Approximately 50-60% of a 5% (w/v) xylan preparation could be hydrolyzed and quantitatively converted to 2,3-butanediol using this procedure. Although enzymatic hydrolysis was optimal at pH 5.0 and 50/sup 0/C, the combined hydrolysis and fermentation was most efficient at pH 6.5 and 30/sup 0/C. Combined hydrolysis and fermentation resulted in butanediol levels that were 20-40% higher than could be obtained with a separate hydrolysis and fermentation process. The hemicellulose-rich water-soluble fractions obtained from a variety of steam-exploded agricultural residues could be readily used by the combined hydrolysis and fermentation approach resulting in butanediol yields of 0.4-0.5 g/g of reducing sugar utilized.

  12. Ruthenium(II)-catalyzed direct addition of indole/pyrrole C2-H bonds to alkynes.

    Science.gov (United States)

    Liang, Libo; Fu, Shaomin; Lin, Dongen; Zhang, Xiao-Qi; Deng, Yuanfu; Jiang, Huanfeng; Zeng, Wei

    2014-10-17

    A ruthenium-catalyzed C2-hydroindolation of alkynes has been achieved. This protocol provides a rapid and concise access to kinds of 2-alkenyl-substituted N-(2-pyridyl)indoles in which the pyridyl moiety can be easily removed to afford free (N-H) indoles under mild conditions. Various arenes and alkynes, including electron-deficient and electron-rich internal alkynes and terminal alkynes, allow for this transformation.

  13. Platinum-Catalyzed, Terminal-Selective C(sp(3))-H Oxidation of Aliphatic Amines.

    Science.gov (United States)

    Lee, Melissa; Sanford, Melanie S

    2015-10-14

    This Communication describes the terminal-selective, Pt-catalyzed C(sp(3))-H oxidation of aliphatic amines without the requirement for directing groups. CuCl2 is employed as a stoichiometric oxidant, and the reactions proceed in high yield at Pt loadings as low as 1 mol%. These transformations are conducted in the presence of sulfuric acid, which reacts with the amine substrates in situ to form ammonium salts. We propose that protonation of the amine serves at least three important roles: (i) it renders the substrates soluble in the aqueous reaction medium; (ii) it limits binding of the amine nitrogen to Pt or Cu; and (iii) it electronically deactivates the C-H bonds proximal to the nitrogen center. We demonstrate that this strategy is effective for the terminal-selective C(sp(3))-H oxidation of a variety of primary, secondary, and tertiary amines.

  14. Synthesis of oxindole from acetanilide via Ir(iii)-catalyzed C-H carbenoid functionalization.

    Science.gov (United States)

    Patel, Pitambar; Borah, Gongutri

    2016-12-22

    Herein we disclose the first report on the synthesis of oxindole derivatives from acetanilide via Ir(iii)-catalyzed intermolecular C-H functionalization with diazotized Meldrum's acid. A broad range of substituted anilides were found to react smoothly under the Ir(iii)-catalytic system to afford the corresponding N-protected oxindoles. The N-protecting groups, such as Ac, Bz or Piv, can be easily removed to furnish the oxindole. Various synthetic applications of the synthesized oxindole were also demonstrated.

  15. Study of the hydrolysis of acetonitrile using different brønsted acid models : zeolite-type and HCl(H2O)x clusters

    NARCIS (Netherlands)

    Barbosa, Louis; Santen, van R.A.

    2000-01-01

    The hydrolysis of acetonitrile has been studied theoretically by different ab initio methods (RHF, DFT, and MP2). Two Brønsted acid catalysts have been compared: zeolite and HCl(H2O)x=2,1 clusters. Some interesting analogies have been found for the reaction path catalyzed by these different acids,

  16. Redox-neutral rhodium-catalyzed C-H functionalization of arylamine N-oxides with diazo compounds: primary C(sp(3))-H/C(sp(2))-H activation and oxygen-atom transfer.

    Science.gov (United States)

    Zhou, Bing; Chen, Zhaoqiang; Yang, Yaxi; Ai, Wen; Tang, Huanyu; Wu, Yunxiang; Zhu, Weiliang; Li, Yuanchao

    2015-10-05

    An unprecedented rhodium(III)-catalyzed regioselective redox-neutral annulation reaction of 1-naphthylamine N-oxides with diazo compounds was developed to afford various biologically important 1H-benzo[g]indolines. This coupling reaction proceeds under mild reaction conditions and does not require external oxidants. The only by-products are dinitrogen and water. More significantly, this reaction represents the first example of dual functiaonalization of unactivated a primary C(sp(3) )H bond and C(sp(2) )H bond with diazocarbonyl compounds. DFT calculations revealed that an intermediate iminium is most likely involved in the catalytic cycle. Moreover, a rhodium(III)-catalyzed coupling of readily available tertiary aniline N-oxides with α-diazomalonates was also developed under external oxidant-free conditions to access various aminomandelic acid derivatives by an O-atom-transfer reaction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Copper-Catalyzed Oxidative Reaction of β-Keto Sulfones with Alcohols via C-S Bond Cleavage: Reaction Development and Mechanism Study.

    Science.gov (United States)

    Du, Bingnan; Wang, Wenmin; Wang, Yang; Qi, Zhenghang; Tian, Jiaqi; Zhou, Jie; Wang, Xiaochen; Han, Jianlin; Ma, Jing; Pan, Yi

    2018-02-16

    A Cu-catalyzed cascade oxidative radical process of β-keto sulfones with alcohols has been achieved by using oxygen as an oxidant. In this reaction, β-keto sulfones were converted into sulfinate esters under the oxidative conditions via cleavage of C-S bond. Experimental and computational studies demonstrate that a new pathway is involved in this reaction, which proceeds through the formation of the key four-coordinated Cu II intermediate, O-O bond homolysis induced C-S bond cleavage and Cu-catalyzed esterification to form the final products. This reaction provides a new strategy to sulfonate esters and enriches the research content of C-S bond cleavage and transformations. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Glucose obtained from rice bran by ultrasound-assisted enzymatic hydrolysis

    Directory of Open Access Journals (Sweden)

    Raquel Cristine Kuhn

    2015-05-01

    Full Text Available In this work ultrasound-assisted solid-state enzymatic hydrolysis of rice bran to obtain fermentable sugars was investigated. For this purpose, process variables such as temperature, enzyme concentration and moisture content were evaluated during the enzymatic hydrolysis with and without ultrasound irradiation. The enzyme used is a blend of amylases derived from genetically modified strains of Trichoderma reesei. Kinetic of the enzymatic hydrolysis of rice bran at the constant-reaction rate period were measured. The best results for the ultrasound-assisted enzymatic hydrolysis was obtained using 3 wt% of enzyme, 60 oC and moisture content of 65 wt%, yielding 0.38 g sugar/g rice bran, whereas for the hydrolysis in the absence of ultrasound the highest yield was 0.20 g sugar/g rice bran using 3 wt% of enzyme, 60 oC and moisture content of 50 wt%. The use of ultrasound-assisted enzymatic hydrolysis of rice bran was intensified, obtaining around 74% more fermentable sugar than in the absence, showing that the use of ultrasound is a promising technology to be used in enzymatic reaction as an alternative of process intensification.

  19. Enzymatic hydrolysis of organic phosphorus in swine manure and soil.

    Science.gov (United States)

    He, Zhongqi; Griffin, Timothy S; Honeycutt, C Wayne

    2004-01-01

    Organic phosphorus (Po) exists in many chemical forms that differ in their susceptibility to hydrolysis and, therefore, bioavailability to plants and microorganisms. Identification and quantification of these forms may significantly contribute to effective agricultural P management. Phosphatases catalyze reactions that release orthophosphate (Pi) from Po compounds. Alkaline phosphatase in tris-HCl buffer (pH 9.0), wheat (Triticum aestivum L.) phytase in potassium acetate buffer (pH 5.0), and nuclease P1 in potassium acetate buffer (pH 5.0) can be used to classify and quantify Po in animal manure. Background error associated with different pH and buffer systems is observed. In this study, we improved the enzymatic hydrolysis approach and tested its applicability for investigating Po in soils, recognizing that soil and manure differ in numerous physicochemical properties. We applied (i) acid phosphatase from potato (Solanum tuberosum L.), (ii) acid phosphatases from both potato and wheat germ, and (iii) both enzymes plus nuclease P1 to identify and quantify simple labile monoester P, phytate (myo-inositol hexakis phosphate)-like P, and DNA-like P, respectively, in a single pH/buffer system (100 mM sodium acetate, pH 5.0). This hydrolysis procedure released Po in sequentially extracted H2O, NaHCO3, and NaOH fractions of swine (Sus scrofa) manure, and of three sandy loam soils. Further refinement of the approach may provide a universal tool for evaluating hydrolyzable Po from a wide range of sources.

  20. The hydrolysis of iron(III) and iron(ll) ions between 25 deg C and 375 deg C

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Derek

    1971-11-15

    Some data on the stabilities of the known iron (III) and iron (II) ions are presented, that have been obtained in a theoretical study of the iron-water system at temperatures up to the critical temperature. In this study, estimates of the stability constants of the various ions in dilute solution have been made by a method based on the equations of classical thermodynamics and empirical equations for the change with temperature of ionic heat capacity. The data indicate that hydrolysis increases so rapidly with temperature that the Fe+3 - ion is practically non-existent above about 150 deg C and, except in very acid solutions, the Fe+2 - ion is a relatively minor constituent above about 250 deg C. The most stable of the ions over a wide range of conditions are probably Fe(OH){sub 2}+ , Fe(OH)+ and HFeO{sub 2}-

  1. Linking Hydrolysis Performance to Trichoderma reesei Cellulolytic Enzyme Profile

    DEFF Research Database (Denmark)

    Lehmann, Linda Olkjær; Petersen, Nanna; I. Jørgensen, Christian

    2016-01-01

    Trichoderma reesei expresses a large number of enzymes involved in lignocellulose hydrolysis and the mechanism of how these enzymes work together is too complex to study by traditional methods, e.g. by spiking with single enzymes and monitoring hydrolysis performance. In this study a multivariate...... approach, partial least squares regression, was used to see if it could help explain the correlation between enzyme profile and hydrolysis performance. Diverse enzyme mixtures were produced by Trichoderma reesei Rut-C30 by exploiting various fermentation conditions and used for hydrolysis of washed...

  2. Kinetics of the hydrolysis of polysaccharide galacturonic acid and neutral sugars chains from flaxseed mucilage

    Directory of Open Access Journals (Sweden)

    Happi Emaga, T.

    2012-01-01

    Full Text Available Different hydrolysis procedures of flaxseed polysaccharides (chemical and enzymatic were carried out with H2SO4, HCl and TFA at different acid concentrations (0.2, 1 and 2 M and temperatures (80 and 100°C. Enzymatic and combined chemical and enzymatic hydrolyses of polysaccharide from flaxseed mucilage were also studied. Acid hydrolysis conditions (2 M H2SO4, 4 h, 100°C are required to quantify total monosaccharide content of flaxseed mucilage. The enzymatic pathway (Pectinex™ Ultra SP limits sugar destruction during hydrolysis, but it is also insufficient for complete depolymerization. The combination of the two treatments, i.e. moderate chemical hydrolysis (0.2 M H2SO4, 80°C, 48 h combined with enzymatic hydrolysis is not more effective compared to chemical hydrolysis in drastic conditions (2 M H2SO4 at 100°C. The strong interaction between the neutral and acid fractions of flaxseed mucilage may hinder total release of sugar residues. Physical treatment prior to the hydrolysis could be necessary to achieve complete depolymerisation of flaxseed mucilage.

  3. Cu-catalyzed C(sp³)-H bond activation reaction for direct preparation of cycloallyl esters from cycloalkanes and aromatic aldehydes.

    Science.gov (United States)

    Zhao, Jincan; Fang, Hong; Han, Jianlin; Pan, Yi

    2014-05-02

    Cu-catalyzed dehydrogenation-olefination and esterification of C(sp(3))-H bonds of cycloalkanes with TBHP as an oxidant has been developed. The reaction involves four C-H bond activations and gives cycloallyl ester products directly from cycloalkanes and aromatic aldehydes.

  4. Direct Functionalization of Nitrogen Heterocycles via Rh-Catalyzed C-H Bond Activation

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Jared; Bergman, Robert; Ellman, Jonathan

    2008-02-04

    Nitrogen heterocycles are present in many compounds of enormous practical importance, ranging from pharmaceutical agents and biological probes to electroactive materials. Direct funtionalization of nitrogen heterocycles through C-H bond activation constitutes a powerful means of regioselectively introducing a variety of substituents with diverse functional groups onto the heterocycle scaffold. Working together, our two groups have developed a family of Rh-catalyzed heterocycle alkylation and arylation reactions that are notable for their high level of functional-group compatibility. This Account describes their work in this area, emphasizing the relevant mechanistic insights that enabled synthetic advances and distinguished the resulting transformations from other methods. They initially discovered an intramolecular Rh-catalyzed C-2-alkylation of azoles by alkenyl groups. That reaction provided access to a number of di-, tri-, and tetracyclic azole derivatives. They then developed conditions that exploited microwave heating to expedite these reactions. While investigating the mechanism of this transformation, they discovered that a novel substrate-derived Rh-N-heterocyclic carbene (NHC) complex was involved as an intermediate. They then synthesized analogous Rh-NHC complexes directly by treating precursors to the intermediate [RhCl(PCy{sub 3}){sub 2}] with N-methylbenzimidazole, 3-methyl-3,4-dihydroquinazolein, and 1-methyl-1,4-benzodiazepine-2-one. Extensive kinetic analysis and DFT calculations supported a mechanism for carbene formation in which the catalytically active RhCl(PCy{sub 3}){sub 2} fragment coordinates to the heterocycle before intramolecular activation of the C-H bond occurs. The resulting Rh-H intermediate ultimately tautomerizes to the observed carbene complex. With this mechanistic information and the discovery that acid co-catalysts accelerate the alkylation, they developed conditions that efficiently and intermolecularly alkylate a variety of

  5. Lactose Hydrolysis in Milk and Dairy Whey Using Microbial β-Galactosidases

    Directory of Open Access Journals (Sweden)

    Michele Dutra Rosolen

    2015-01-01

    Full Text Available This work aimed at evaluating the influence of enzyme concentration, temperature, and reaction time in the lactose hydrolysis process in milk, cheese whey, and whey permeate, using two commercial β-galactosidases of microbial origins. We used Aspergillus oryzae (at temperatures of 10 and 55°C and Kluyveromyces lactis (at temperatures of 10 and 37°C β-galactosidases, both in 3, 6, and 9 U/mL concentrations. In the temperature of 10°C, the K. lactis β-galactosidase enzyme is more efficient in the milk, cheese whey, and whey permeate lactose hydrolysis when compared to A. oryzae. However, in the enzyme reaction time and concentration conditions evaluated, 100% lactose hydrolysis was not reached using the K. lactis β-galactosidase. The total lactose hydrolysis in whey and permeate was obtained with the A. oryzae enzyme, when using its optimum temperature (55°C, at the end of a 12 h reaction, regardless of the enzyme concentration used. For the lactose present in milk, this result occurred in the concentrations of 6 and 9 U/mL, with the same time and temperature conditions. The studied parameters in the lactose enzymatic hydrolysis are critical for enabling the application of β-galactosidases in the food industry.

  6. Palladium-Catalyzed C-H Functionalization Using Guanidine as a Directing Group: Ortho Arylation and Olefination of Arylguanidines

    Science.gov (United States)

    Shao, Jiaan; Chen, Wenteng; Giulianotti, Marc A.; Houghten, Richard A.; Yu, Yongping

    2012-01-01

    Palladium-catalyzed C-H functionalization using guanidine as the directing group was achieved under mild reaction conditions. Various guanidine derivatives were produced in moderate to good yields by using simple unactivated arenes or ethyl acrylate as the source of arylation or olefination respectively. PMID:23095022

  7. Expedient synthesis of C-aryl carbohydrates by consecutive biocatalytic benzoin and aldol reactions.

    Science.gov (United States)

    Hernández, Karel; Parella, Teodor; Joglar, Jesús; Bujons, Jordi; Pohl, Martina; Clapés, Pere

    2015-02-16

    The introduction of aromatic residues connected by a C-C bond into the non-reducing end of carbohydrates is highly significant for the development of innovative structures with improved binding affinity and selectivity (e.g., C-aril-sLex). In this work, an expedient asymmetric "de novo" synthetic route to new aryl carbohydrate derivatives based on two sequential stereoselectively biocatalytic carboligation reactions is presented. First, the benzoin reaction of aromatic aldehydes to dimethoxyacetaldehyde is conducted, catalyzed by benzaldehyde lyase from Pseudomonas fluorescens biovar I. Then, the α-hydroxyketones formed are reduced by using NaBH4 yielding the anti diol. After acetal hydrolysis, the aldol addition of dihydroxyacetone, hydroxyacetone, or glycolaldehyde catalyzed by the stereocomplementary D-fructose-6-phosphate aldolase and L-rhamnulose-1-phosphate aldolase is performed. Both aldolases accept unphosphorylated donor substrates, avoiding the need of handling the phosphate group that the dihydroxyacetone phosphate-dependent aldolases require. In this way, 6-C-aryl-L-sorbose, 6-C-aryl-L-fructose, 6-C-aryl-L-tagatose, and 5-C-aryl-L-xylose derivatives are prepared by using this methodology. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Electroless Nickel-Based Catalyst for Diffusion Limited Hydrogen Generation through Hydrolysis of Borohydride

    Directory of Open Access Journals (Sweden)

    Shannon P. Anderson

    2013-07-01

    Full Text Available Catalysts based on electroless nickel and bi-metallic nickel-molybdenum nanoparticles were synthesized for the hydrolysis of sodium borohydride for hydrogen generation. The catalysts were synthesized by polymer-stabilized Pd nanoparticle-catalyzation and activation of Al2O3 substrate and electroless Ni or Ni-Mo plating of the substrate for selected time lengths. Catalytic activity of the synthesized catalysts was tested for the hydrolyzation of alkaline-stabilized NaBH4 solution for hydrogen generation. The effects of electroless plating time lengths, temperature and NaBH4 concentration on hydrogen generation rates were analyzed and discussed. Compositional analysis and surface morphology were carried out for nano-metallized Al2O3 using Scanning Electron Micrographs (SEM and Energy Dispersive X-Ray Microanalysis (EDAX. The as-plated polymer-stabilized electroless nickel catalyst plated for 10 min and unstirred in the hydrolysis reaction exhibited appreciable catalytic activity for hydrolysis of NaBH4. For a zero-order reaction assumption, activation energy of hydrogen generation using the catalyst was estimated at 104.6 kJ/mol. Suggestions are provided for further work needed prior to using the catalyst for portable hydrogen generation from aqueous alkaline-stabilized NaBH4 solution for fuel cells.

  9. Cellulose accessibility limits the effectiveness of minimum cellulase loading on the efficient hydrolysis of pretreated lignocellulosic substrates

    Directory of Open Access Journals (Sweden)

    Saddler Jack N

    2011-02-01

    Full Text Available Abstract A range of lignocellulosic feedstocks (including agricultural, softwood and hardwood substrates were pretreated with either sulfur dioxide-catalyzed steam or an ethanol organosolv procedure to try to establish a reliable assessment of the factors governing the minimum protein loading that could be used to achieve efficient hydrolysis. A statistical design approach was first used to define what might constitute the minimum protein loading (cellulases and β-glucosidase that could be used to achieve efficient saccharification (defined as at least 70% glucan conversion of the pretreated substrates after 72 hours of hydrolysis. The likely substrate factors that limit cellulose availability/accessibility were assessed, and then compared with the optimized minimum amounts of protein used to obtain effective hydrolysis. The optimized minimum protein loadings to achieve efficient hydrolysis of seven pretreated substrates ranged between 18 and 63 mg protein per gram of glucan. Within the similarly pretreated group of lignocellulosic feedstocks, the agricultural residues (corn stover and corn fiber required significantly lower protein loadings to achieve efficient hydrolysis than did the pretreated woody biomass (poplar, douglas fir and lodgepole pine. Regardless of the substantial differences in the source, structure and chemical composition of the feedstocks, and the difference in the pretreatment technology used, the protein loading required to achieve efficient hydrolysis of lignocellulosic substrates was strongly dependent on the accessibility of the cellulosic component of each of the substrates. We found that cellulose-rich substrates with highly accessible cellulose, as assessed by the Simons' stain method, required a lower protein loading per gram of glucan to obtain efficient hydrolysis compared with substrates containing less accessible cellulose. These results suggest that the rate-limiting step during hydrolysis is not the catalytic

  10. Trapping of intermediates with substrate analog HBOCoA in the polymerizations catalyzed by class III polyhydroxybutyrate (PHB) synthase from Allochromatium vinosum.

    Science.gov (United States)

    Chen, Chao; Cao, Ruikai; Shrestha, Ruben; Ward, Christina; Katz, Benjamin B; Fischer, Christopher J; Tomich, John M; Li, Ping

    2015-05-15

    Polyhydroxybutyrate (PHB) synthases (PhaCs) catalyze the formation of biodegradable PHB polymers that are considered as an ideal alternative to petroleum-based plastics. To provide strong evidence for the preferred mechanistic model involving covalent and noncovalent intermediates, a substrate analog HBOCoA was synthesized chemoenzymatically. Substitution of sulfur in the native substrate HBCoA with an oxygen in HBOCoA enabled detection of (HB)nOCoA (n = 2-6) intermediates when the polymerization was catalyzed by wild-type (wt-)PhaECAv at 5.84 h(-1). This extremely slow rate is due to thermodynamically unfavorable steps that involve the formation of enzyme-bound PHB species (thioesters) from corresponding CoA oxoesters. Synthesized standards (HB)nOCoA (n = 2-3) were found to undergo both reacylation and hydrolysis catalyzed by the synthase. Distribution of the hydrolysis products highlights the importance of the penultimate ester group as previously suggested. Importantly, the reaction between primed synthase [(3)H]-sT-PhaECAv and HBOCoA yielded [(3)H]-sTet-O-CoA at a rate constant faster than 17.4 s(-1), which represents the first example that a substrate analog undergoes PHB chain elongation at a rate close to that of the native substrate (65.0 s(-1)). Therefore, for the first time with a wt-synthase, strong evidence was obtained to support our favored PHB chain elongation model.

  11. Adsorption of acetanilide herbicides on soil and its components. II. Adsorption and catalytic hydrolysis of diethatyl-ethyl on saturated Na(+)-, K(+)-, Ca(2+)-, and Mg(2+)-montmorillonite.

    Science.gov (United States)

    Liu, W P; Fang, Z; Liu, H J; Yang, W C

    2001-04-01

    Adsorption and catalytic hydrolysis of the herbicide diethatyl-ethyl [N-chloroacetyl-N-(2,6-diethylphenyl)glycine ethyl ester] on homoionic Na(+)-, K(+)-, Ca(2+)-, and Mg(2+)-montmorillonite clays were investigated in water solution. The Freundlich adsorption coefficient, Ki, got from isotherms on clay followed the order of Na+ approximately K+ > Mg2+ approximately Ca2+. Analysis of FT-IR spectra of diethatyl-ethyl adsorbed on clay suggests probable bonding at the carboxyl and amide carbonyl groups of the herbicide. The rate of herbicide hydrolysis in homoionic clay suspensions followed the same order as that for adsorption, indicating that adsorption may have preceded and thus caused hydrolysis. Preliminary product identification showed that hydrolysis occurred via nucleophilic substitution at the carboxyl carbon, causing the cleavage of the ester bond and formation of diethatyl and its dechlorinated derivative, and at the amide carbon, yielding an ethyl ester derivative and its acid. These pathways also suggest that hydrolysis of diethatyl-ethyl was catalyzed by adsorption on the clay surface.

  12. Bovine serum albumin-catalyzed deprotonation of [1-(13)C]glycolaldehyde: protein reactivity toward deprotonation of the alpha-hydroxy alpha-carbonyl carbon.

    Science.gov (United States)

    Go, Maybelle K; Malabanan, M Merced; Amyes, Tina L; Richard, John P

    2010-09-07

    Bovine serum albumin (BSA) in D(2)O at 25 degrees C and pD 7.0 was found to catalyze the deuterium exchange reactions of [1-(13)C]glycolaldehyde ([1-(13)C]GA) to form [1-(13)C,2-(2)H]GA and [1-(13)C,2,2-di-(2)H]GA. The formation of [1-(13)C,2-(2)H]GA and [1-(13)C,2,2-di-(2)H]GA in a total yield of 51 +/- 3% was observed at early reaction times, and at later times, [1-(13)C,2-(2)H]GA was found to undergo BSA-catalyzed conversion to [1-(13)C,2,2-di-(2)H]GA. The overall second-order rate constant for these deuterium exchange reactions [(k(E))(P)] equals 0.25 M(-1) s(-1). By comparison, (k(E))(P) values of 0.04 M(-1) s(-1) [Go, M. K., Amyes, T. L., and Richard, J. P. (2009) Biochemistry 48, 5769-5778] and 0.06 M(-1) s(-1) [Go, M. K., Koudelka, A., Amyes, T. L., and Richard, J. P. (2010) Biochemistry 49, 5377-5389] have been determined for the wild-type- and K12G mutant TIM-catalyzed deuterium exchange reactions of [1-(13)C]GA, respectively, to form [1-(13)C,2,2-di-(2)H]GA. These data show that TIM and BSA exhibit a modest catalytic activity toward deprotonation of the alpha-hydroxy alpha-carbonyl carbon. We suggest that this activity is intrinsic to many globular proteins, and that it must be enhanced to demonstrate meaningful de novo design of protein catalysts of proton transfer at alpha-carbonyl carbon.

  13. Mass Spectrometry Imaging Reveals Elevated Glomerular ATP/AMP in Diabetes/obesity and Identifies Sphingomyelin as a Possible Mediator

    Directory of Open Access Journals (Sweden)

    Satoshi Miyamoto

    2016-05-01

    Full Text Available AMP-activated protein kinase (AMPK is suppressed in diabetes and may be due to a high ATP/AMP ratio, however the quantitation of nucleotides in vivo has been extremely difficult. Via matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI to localize renal nucleotides we found that the diabetic kidney had a significant increase in glomerular ATP/AMP ratio. Untargeted MALDI-MSI analysis revealed that a specific sphingomyelin species (SM(d18:1/16:0 accumulated in the glomeruli of diabetic and high-fat diet-fed mice compared with wild-type controls. In vitro studies in mesangial cells revealed that exogenous addition of SM(d18:1/16:0 significantly elevated ATP via increased glucose consumption and lactate production with a consequent reduction of AMPK and PGC1α. Furthermore, inhibition of sphingomyelin synthases reversed these effects. Our findings suggest that AMPK is reduced in the diabetic kidney due to an increase in the ATP/AMP ratio and that SM(d18:1/16:0 could be responsible for the enhanced ATP production via activation of the glycolytic pathway.

  14. Sphingomyelin lipidosis (Niemann-Pick disease) in a juvenile raccoon (Procyon lotor).

    Science.gov (United States)

    Vapniarsky, N; Wenger, D A; Scheenstra, D; Mete, A

    2013-01-01

    A wild caught juvenile male raccoon with neurological disease was humanely destroyed due to poor prognosis. Necropsy examination revealed hepatomegaly, splenomegaly and multicentric lymphadenomegaly with diffuse hepatic pallor and pulmonary consolidation with pinpoint pale subpleural foci. Microscopically, there was marked pale cytoplasmic swelling of the central and peripheral neurons as well as the glial cells in the brain, accompanied by multiorgan infiltration by abundant foamy macrophages. Ultrastructural investigation revealed accumulation of concentrically arranged lamellar material within lysosomes of the affected neurons, macrophages and endothelial cells. Biochemical enzymatic analysis detected sphingomyelinase deficiency and lysosomal storage disease consistent with sphingomyelin lipidosis (Niemann-Pick disease [NPD]) was diagnosed. This is the first report of NPD in a raccoon. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. New Palladium-Catalyzed Approaches to Heterocycles and Carbocycles

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Qinhua [Iowa State Univ., Ames, IA (United States)

    2004-12-19

    The tert-butylimines of o-(1-alkynyl)benzaldehydes and analogous pyridinecarbaldehydes have been cyclized under very mild reaction conditions in the presence of I2, ICl, PhSeCl, PhSCl and p-O2NC6H4SCl to give the corresponding halogen-, selenium- and sulfur-containing disubstituted isoquinolines and naphthyridines, respectively. Monosubstituted isoquinolines and naphthyridines have been synthesized by the metal-catalyzed ring closure of these same iminoalkynes. This methodology accommodates a variety of iminoalkynes and affords the anticipated heterocycles in moderate to excellent yields. The Pd(II)-catalyzed cyclization of 2-(1-alkynyl)arylaldimines in the presence of various alkenes provides an efficient way to synthesize a variety of 4-(1-alkenyl)-3-arylisoquinolines in moderate to excellent yields. The introduction of an ortho-methoxy group on the arylaldimine promotes the Pd-catalyzed cyclization and stabilizes the resulting Pd(II) intermediate, improving the yields of the isoquinoline products. Highly substituted naphthalenes have been synthesized by the palladium-catalyzed annulation of a variety of internal alkynes, in which two new carbon-carbon bonds are formed in a single step under relatively mild reaction conditions. This method has also been used to synthesize carbazoles, although a higher reaction temperature is necessary. The process involves arylpalladation of the alkyne, followed by intramolecular Heck olefination and double bond isomerization. This method accommodates a variety of functional groups and affords the anticipated highly substituted naphthalenes and carbazoles in good to excellent yields. Novel palladium migratiodarylation methodology for the synthesis of complex fused polycycles has been developed, in which one or more sequential Pd-catalyzed intramolecular migration processes involving C-H activation are employed. The chemistry works best with electron-rich aromatics, which is in agreement

  16. Liposomes as potential masking agents in sport doping. Part 1: analysis of phospholipids and sphingomyelins in drugs and biological fluids by aqueous normal-phase liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Esposito, Simone; Colicchia, Sonia; de la Torre, Xavier; Mazzarino, Monica; Botrè, Francesco

    2017-01-01

    In the present work, aqueous normal-phase liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), in different acquisition modes, was employed for the direct analysis and profiling of nine phospholipid classes (phosphatidic acids, phosphatidylserines, phosphatidylethanolamines, lysophosphatidylethanolamines, phosphatidylglycerols, phosphatidylinositols, phosphatidylcholines, lysophosphatidylcholines, and sphingomyelins) in biological and pharmaceutical matrices. After chromatographic separation by a diol column, detection and elucidation of phospholipid and sphingomyelin classes and molecular species were performed by different scan acquisition modes. For screening analysis, molecular ions [M + H] + were detected in positive precursor ion scan of m/z 184 for the classes of phosphatidylcholines, lyso-phosphatidylcholines and sphingomyelins; while phosphatidylethanolamines and lyso-phosphatidylethanolamines were detected monitoring neutral loss scan of 141 Da; and phosphatidylserines detected using neutral loss scan of 184 Da. Molecular ions [M-H] - were instead acquired in negative precursor ion scan of m/z 153 for the classes of phosphatidic acids and phosphatidylglycerols; and of m/z 241 for the phosphatidylinositols. For the identification of the single molecular species, product ion scan mass spectra of the [M + HCOO] - ions for phosphatidylcholines and [M + H] + ions for the other phospholipids considered were determined for each class and compared with the fragmentation pattern of model phospholipid reference standard. By this approach, nearly 100 phospholipids and sphingomyelins were detected and identified. The optimized method was then used to characterize the phospholipid and sphingomyelin profiles in human plasma and urine samples and in two phospholipid-based pharmaceutical formulations, proving that it also allows to discriminate compounds of endogenous origin from those resulting from the intake of pharmaceutical products

  17. Room-temperature Pd-catalyzed C-H chlorination by weak coordination: one-pot synthesis of 2-chlorophenols with excellent regioselectivity.

    Science.gov (United States)

    Sun, Xiuyun; Sun, Yonghui; Zhang, Chao; Rao, Yu

    2014-02-07

    A room-temperature Pd(II)-catalyzed regioselective chlorination reaction has been developed for a facile one-pot synthesis of a broad range of 2-chlorophenols. The reaction demonstrates an excellent regioselectivity and reactivity for C-H chlorination. This reaction represents one of the rare examples of mild C-H functionalization at ambient temperature.

  18. Bioorthogonal Diversification of Peptides through Selective Ruthenium(II)-Catalyzed C-H Activation.

    Science.gov (United States)

    Schischko, Alexandra; Ren, Hongjun; Kaplaneris, Nikolaos; Ackermann, Lutz

    2017-02-01

    Methods for the chemoselective modification of amino acids and peptides are powerful techniques in biomolecular chemistry. Among other applications, they enable the total synthesis of artificial peptides. In recent years, significant momentum has been gained by exploiting palladium-catalyzed cross-coupling for peptide modification. Despite major advances, the prefunctionalization elements on the coupling partners translate into undesired byproduct formation and lengthy synthetic operations. In sharp contrast, we herein illustrate the unprecedented use of versatile ruthenium(II)carboxylate catalysis for the step-economical late-stage diversification of α- and β-amino acids, as well as peptides, through chemo-selective C-H arylation under racemization-free reaction conditions. The ligand-accelerated C-H activation strategy proved water-tolerant and set the stage for direct fluorescence labelling as well as various modes of peptide ligation with excellent levels of positional selectivity in a bioorthogonal fashion. The synthetic utility of our approach is further demonstrated by twofold C-H arylations for the complexity-increasing assembly of artificial peptides within a multicatalytic C-H activation manifold. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Direct Kinetic Evidence for the Formation of an Acylpyridinium Intermediate in Synthetic p-Nitrophenyl Esterase-Catalyzed Hydrolysis Reactions

    National Research Council Canada - National Science Library

    Wang, Guang-Jia

    1996-01-01

    .... The deacylation rate was also found to exhibit a maximum for the same substrate 2 (n=6). These results are similar to those previously reported with cholesterol esterase as catalyst for the same hydrolysis reaction...

  20. Orientation and Order of the Amide Group of Sphingomyelin in Bilayers Determined by Solid-State NMR

    Science.gov (United States)

    Matsumori, Nobuaki; Yamaguchi, Toshiyuki; Maeta, Yoshiko; Murata, Michio

    2015-01-01

    Sphingomyelin (SM) and cholesterol (Chol) are considered essential for the formation of lipid rafts; however, the types of molecular interactions involved in this process, such as intermolecular hydrogen bonding, are not well understood. Since, unlike other phospholipids, SM is characterized by the presence of an amide group, it is essential to determine the orientation of the amide and its order in the lipid bilayers to understand the nature of the hydrogen bonds in lipid rafts. For this study, 1′-13C-2-15N-labeled and 2′-13C-2-15N-labeled SMs were prepared, and the rotational-axis direction and order parameters of the SM amide in bilayers were determined based on 13C and 15N chemical-shift anisotropies and intramolecular 13C-15N dipole coupling constants. Results revealed that the amide orientation was minimally affected by Chol, whereas the order was enhanced significantly in its presence. Thus, Chol likely promotes the formation of an intermolecular hydrogen-bond network involving the SM amide without significantly changing its orientation, providing a higher order to the SM amide. To our knowledge, this study offers new insight into the significance of the SM amide orientation with regard to molecular recognition in lipid rafts, and therefore provides a deeper understanding of the mechanism of their formation. PMID:26083921

  1. Hydrolysis mechanism of BH4- in moist acetonitrile. III. Kinetic isotope effects

    International Nuclear Information System (INIS)

    Meeks, B.S. Jr.; Kreevoy, M.M.

    1979-01-01

    The present work and a concurrent paper show that, in the presence of acetic acid, BH 4 - in acetonitrile is rapidly converted to BH 3 OCOCH 3 - and that previous kinetic studies of the hydrolysis of BH 4 - in such solutions actually referred to the hydrolysis of BH 3 OCOCH 3 - . As previously shown, the substrate (now shown to be BH 3 OCOCH 3 - ) complexes with acetic acid, with a complexing constant of about 160. That complex hydrolyzes by spontaneous and water-catalyzed paths. The present paper shows that the latter reaction is accelerated 15 to 40% by the substitution of D for H on boron. The rate is reduced, by a factor of approx. 1.75, by replacing all the hydroxylic hydrogen with deuterium. These results are consistent with BH 3 OC(CH 3 )O . HOCOCH 3 as the acetic acid-substrate complex. The displacement of the incipient biacetate ion by water is rate determining in this process. Isotopic substitution at either position reduces the rate of the spontaneous process. Its mechanism is uncertain. 2 figures, 3 tables

  2. Effects of intact glucosinolates and products produced from glucosinolates in myrosinase-catalyzed hydrolysis on the potato cyst nematode (Globodera rostochiensis Cv. Woll).

    Science.gov (United States)

    Buskov, S; Serra, B; Rosa, E; Sørensen, H; Sørensen, J C

    2002-02-13

    The potato cyst nematode (Globodera rostochiensis cv. Woll) is responsible for large yield losses in the potato crop, and opportunities for reducing the attack of these plant nematode species are, therefore, important. This study has been devoted to the testing of the in vitro effects on the potato cyst nematode of eight glucosinolates [prop-2-enyl-, but-3-enyl-, (R)-4-methylsulfinylbut-3-enyl-, benzyl-, phenethyl-, 4-hydroxybenzyl-, (2S)-2-hydroxybut-3-enyl-, and (2R)-2-hydroxy-2-phenylethylglucosinolate] as well as the effects of the products of this myrosinase-catalyzed hydrolysis. The glucosinolates were used at three concentrations, 0.05, 0.3, and 1.0 mg/mL, in the presence or absence of the enzyme myrosinase. The effects of the compounds on the mortality were monitored every 8 h for a 72 h period. No effects were found for any of the intact glucosinolates. However, when active myrosinase was included with 1 mg/mL phenethylglucosinolate at pH 6.5, 100% mortality was observed within just 16 h. A similar effect was achieved at the same concentration of benzyl- and prop-2-enylglucosinolates in the myrosinase-containing solutions, although longer exposures were required (24 and 40 h, respectively). The main aglucone products released from the glucosinolates with pronounced effects on the nematodes were shown to be the corresponding isothiocyanates. The results suggest that mixtures of these specific glucosinolates and active myrosinase or autolysis of plant materials containing these enzymes and glucosinolates might be used to control the potato cyst nematode in the soil.

  3. Metal-catalyzed living radical polymerization and radical polyaddition for precision polymer synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Mizutani, M; Satoh, K [Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kamigaito, M, E-mail: kamigait@apchem.nagoya-u.ac.j

    2009-08-01

    The metal-catalyzed radical addition reaction can be evolved into two different polymerization mechanisms, i.e.; chain- and step-growth polymerizations, while both the polymerizations are based on the same metal-catalyzed radical formation reaction. The former is a widely employed metal-catalyzed living radical polymerization or atom transfer radical polymerization of common vinyl monomers, and the latter is a novel metal-catalyzed radical polyaddition of designed monomer with an unconjugated C=C double bond and a reactive C-Cl bond in one molecule. The simultaneous ruthenium-catalyzed living radical polymerization of methyl acrylate and radical polyaddition of 3-butenyl 2-chloropropionate was achieved with Ru(Cp*)Cl(PPh{sub 3}){sub 2} to afford the controlled polymers, in which the homopolymer segments with the controlled chain length were connected by the ester linkage.

  4. Catalytic hydrolysis of ammonia borane via cobalt palladium nanoparticles.

    Science.gov (United States)

    Sun, Daohua; Mazumder, Vismadeb; Metin, Önder; Sun, Shouheng

    2011-08-23

    Monodisperse 8 nm CoPd nanoparticles (NPs) with controlled compositions were synthesized by the reduction of cobalt acetylacetonate and palladium bromide in the presence of oleylamine and trioctylphosphine. These NPs were active catalysts for hydrogen generation from the hydrolysis of ammonia borane (AB), and their activities were composition dependent. Among the 8 nm CoPd catalysts tested for the hydrolysis of AB, the Co(35)Pd(65) NPs exhibited the highest catalytic activity and durability. Their hydrolysis completion time and activation energy were 5.5 min and 27.5 kJ mol(-1), respectively, which were comparable to the best Pt-based catalyst reported. The catalytic performance of the CoPd/C could be further enhanced by a preannealing treatment at 300 °C under air for 15 h with the hydrolysis completion time reduced to 3.5 min. This high catalytic performance of Co(35)Pd(65) NP catalyst makes it an exciting alternative in pursuit of practical implementation of AB as a hydrogen storage material for fuel cell applications. © 2011 American Chemical Society

  5. Palladium-catalyzed Suzuki-Miyaura coupling of amides by carbon-nitrogen cleavage: general strategy for amide N-C bond activation.

    Science.gov (United States)

    Meng, Guangrong; Szostak, Michal

    2016-06-15

    The first palladium-catalyzed Suzuki-Miyaura cross-coupling of amides with boronic acids for the synthesis of ketones by sterically-controlled N-C bond activation is reported. The transformation is characterized by operational simplicity using bench-stable, commercial reagents and catalysts, and a broad substrate scope, including substrates with electron-donating and withdrawing groups on both coupling partners, steric-hindrance, heterocycles, halides, esters and ketones. The scope and limitations are presented in the synthesis of >60 functionalized ketones. Mechanistic studies provide insight into the catalytic cycle of the cross-coupling, including the first experimental evidence for Pd insertion into the amide N-C bond. The synthetic utility is showcased by a gram-scale cross-coupling and cross-coupling at room temperature. Most importantly, this process provides a blueprint for the development of a plethora of metal catalyzed reactions of typically inert amide bonds via acyl-metal intermediates. A unified strategy for amide bond activation to enable metal insertion into N-C amide bond is outlined ().

  6. Optimization of dilute acid hydrolysis of Enteromorpha

    Science.gov (United States)

    Feng, Dawei; Liu, Haiyan; Li, Fuchao; Jiang, Peng; Qin, Song

    2011-11-01

    Acid hydrolysis is a simple and direct way to hydrolyze polysaccharides in biomass into fermentable sugars. To produce fermentable sugars effectively and economically for fuel ethanol, we have investigated the hydrolysis of Enteromorpha using acids that are typically used to hydrolyze biomass: H2SO4, HCl, H3PO4 and C4H4O4 (maleic acid). 5%(w/w) Enteromorpha biomass was treated for different times (30, 60, and 90 min) and with different acid concentrations (0.6, 1.0, 1.4, 1.8, and 2.2%, w/w) at 121°C. H2SO4 was the most effective acid in this experiment. We then analyzed the hydrolysis process in H2SO4 in detail using high performance liquid chromatography. At a sulfuric acid concentration of 1.8% and treatment time of 60 min, the yield of ethanol fermentable sugars (glucose and xylose) was high, (230.5 mg/g dry biomass, comprising 175.2 mg/g glucose and 55.3 mg/g xylose), with 48.6% of total reducing sugars being ethanol fermentable. Therefore, Enteromorpha could be a good candidate for production of fuel ethanol. In future work, the effects of temperature and biomass concentration on hydrolysis, and also the fermentation of the hydrolysates to ethanol fuel should be focused on.

  7. [Evaluation of fetal lung maturity using a modified lecithin-sphingomyelin determination and Clements' foam test].

    Science.gov (United States)

    Neumann, G; Gartzke, J; Faber, G

    1978-01-01

    The modified thin layer chromatographic method for the determination of the phospholipids lecithin and sphingomyelin from amniotic fluid is useful in estimating fetal pulmonary maturity. The foam test of Clements is a simple rapid method for screening of suspicious cases of pregnancies at risk and of great value as bed side test even performing by the doctor. In comparing Clements-Test with thin layer chromatographic for L/S-Ratio determination we found a good correlation of 81,8% of all cases.

  8. Combined enzyme hydrolysis of cellulose and yeast fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Savarese, J J; Young, S D

    1978-08-01

    The conversion of cellulose, especially waste cellulosics, into utilizable materials, especially liquid fuel, is a most valuable outcome of cellulase technology pioneered at the US Army Laboratories, Natick, Mass. A process design has been proposed by Wilke for the conversion of cellulosic materials to ethanol and single-cell protein (SCP). The estimated ethanol production cost by this process is at the moment slightly more expensive than ethanol derived from petroleum. This paper deals with a process design improvement which will lower production cost for ethanol obtained via a Wilke or similar type system. We report a process by which the cellulase-catalyzed hydrolysis of cellulose to glucose is coupled with the yeast fermentation of the glucose produced to ethanol and SCP. Both processes take place in the same fermentor thus eliminating the need for the separation of glucose and a second reactor.

  9. Preparation of crystalline starch nanoparticles using cold acid hydrolysis and ultrasonication.

    Science.gov (United States)

    Kim, Hee-Young; Park, Dong June; Kim, Jong-Yea; Lim, Seung-Taik

    2013-10-15

    Waxy maize starch in an aqueous sulfuric acid solution (3.16 M, 14.7% solids) was hydrolyzed for 2-6 days, either isothermally at 40 °C or 4 °C, or at cycled temperatures of 4 and 40 °C (1 day each). The starch hydrolyzates were recovered as precipitates after centrifuging the dispersion (10,000 rpm, 10 min). The yield of starch hydrolyzates depended on the hydrolysis temperature and time, which varied from 6.8% to 78%. The starch hydrolyzed at 40 °C or 4/40 °C exhibited increased crystallinity determined by X-ray diffraction analysis, but melted in broader temperature range (from 60 °C to 110 °C). However, the starch hydrolyzed at 4 °C displayed the crystallinity and melting endotherm similar to those of native starch. The starch hydrolyzates recovered by centrifugation were re-dispersed in water (15% solids), and the dispersion was treated by an ultrasonic treatment (60% amplitude, 3min). The ultrasonication effectively fragmented the starch hydrolyzates to nanoparticles. The hydrolyzates obtained after 6 days of hydrolysis were more resistant to the ultrasonication than those after 2 or 4 days, regardless of hydrolysis temperatures. The starch nanoparticles could be prepared with high yield (78%) and crystallinity by 4 °C hydrolysis for 6 days followed by ultrasonication. Scanning electron microscopy revealed that the starch nanoparticles had globular shapes with diameters ranging from 50 to 90 nm. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Process development of short-chain polyols synthesis from corn stover by combination of enzymatic hydrolysis and catalytic hydrogenolysis

    Directory of Open Access Journals (Sweden)

    Zhen-Hong Fang

    2014-09-01

    Full Text Available Currently short-chain polyols such as ethanediol, propanediol, and butanediol are produced either from the petroleum feedstock or from the starch-based food crop feedstock. In this study, a combinational process of enzymatic hydrolysis with catalytic hydrogenolysis for short-chain polyols production using corn stover as feedstock was developed. The enzymatic hydrolysis of the pretreated corn stover was optimized to produce stover sugars at the minimum cost. Then the stover sugars were purified and hydrogenolyzed into polyols products catalyzed by Raney nickel catalyst. The results show that the yield of short-chain polyols from the stover sugars was comparable to that of the corn-based glucose. The present study provided an important prototype for polyols production from lignocellulose to replace the petroleum- or corn-based polyols for future industrial applications.

  11. Study on the technology of compound enzymatic hydrolysis of whole passion fruit

    Science.gov (United States)

    Yang, Yu-xia; Duan, Zhen-hua; Kang, Chao; Zhu, Xiang-hao; Li, Ding-jin

    2017-12-01

    Fresh Whole Passion Fruit was used as raw material, The enzymatic hydrolysis technology of Passion Fruit by Complex enzyme were studied, The effects of enzyme dosage, Enzyme ratio(cellulose: pectinase), pH, temperature and time on the hydrolysis were investigated by single-tests and orthogonal tests, the hydrolysis indicators of single-factor tests and orthogonal tests were juice yield. The optimal hydrolysis conditions of Passion Fruit by Complex enzyme were enzyme dosage 0.12%, Enzyme ratio 5:1, hydrolysis temperature 50°C, pH4.0 and time 3.5 h. Under such conditions, juice yield of Passion Fruit was 92.91%.

  12. Rh(iii)-catalyzed C-H olefination of N-pentafluoroaryl benzamides using air as the sole oxidant.

    Science.gov (United States)

    Lu, Yi; Wang, Huai-Wei; Spangler, Jillian E; Chen, Kai; Cui, Pei-Pei; Zhao, Yue; Sun, Wei-Yin; Yu, Jin-Quan

    2015-03-01

    The oxidative olefination of a broad array of arenes and heteroarenes with a variety of activated and unactivated olefins has be achieved via a rhodium(iii)-catalyzed C-H activation reaction. The use of an N -pentafluorophenyl benzamide directing group is crucial for achieving catalytic turnovers in the presence of air as the sole oxidant without using a co-oxidant.

  13. Rhodium-catalyzed enantioselective intramolecular C-H silylation for the syntheses of planar-chiral metallocene siloles.

    Science.gov (United States)

    Zhang, Qing-Wei; An, Kun; Liu, Li-Chuan; Yue, Yuan; He, Wei

    2015-06-01

    Reported herein is the rhodium-catalyzed enantioselective C-H bond silylation of the cyclopentadiene rings in Fe and Ru metallocenes. Thus, in the presence of (S)-TMS-Segphos, the reactions took place under very mild conditions to afford metallocene-fused siloles in good to excellent yields and with ee values of up to 97%. During this study it was observed that the steric hindrance of chiral ligands had a profound influence on the reactivity and enantioselectivity of the reaction, and might hold the key to accomplishing conventionally challenging asymmetric C-H silylations. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Effect of bovine serum albumin (BSA) on enzymatic cellulose hydrolysis.

    Science.gov (United States)

    Wang, Hui; Mochidzuki, Kazuhiro; Kobayashi, Shinichi; Hiraide, Hatsue; Wang, Xiaofen; Cui, Zongjun

    2013-06-01

    Bovine serum albumin (BSA) was added to filter paper during the hydrolysis of cellulase. Adding BSA before the addition of the cellulase enhances enzyme activity in the solution, thereby increasing the conversion rate of cellulose. After 48 h of BSA treatment, the BSA adsorption quantities are 3.3, 4.6, 7.8, 17.2, and 28.3 mg/g substrate, each with different initial BSA concentration treatments at 50 °C; in addition, more cellulase was adsorbed onto the filter paper at 50 °C compared with 35 °C. After 48 h of hydrolysis, the free-enzyme activity could not be measured without the BSA treatment, whereas the remaining activity of the filter paper activity was approximately 41 % when treated with 1.0 mg/mL BSA. Even after 96 h of hydrolysis, 25 % still remained. Meanwhile, after 48 h of incubation without substrate, the remaining enzyme activities were increased 20.7 % (from 43.7 to 52.7 %) and 94.8 % (from 23.3 to 45.5 %) at 35 and 50 °C, respectively. Moreover, the effect of the BSA was more obvious at 35 °C compared with 50 °C. When using 15 filter paper cellulase units per gram substrate cellulase loading at 50 °C, the cellulose conversion was increased from 75 % (without BSA treatment) to ≥90 % when using BSA dosages between 0.1 and 1.5 mg/mL. Overall, these results suggest that there are promising strategies for BSA treatment in the reduction of enzyme requirements during the hydrolysis of cellulose.

  15. A process for producing lignin and volatile compounds from hydrolysis liquor.

    Science.gov (United States)

    Khazraie, Tooran; Zhang, Yiqian; Tarasov, Dmitry; Gao, Weijue; Price, Jacquelyn; DeMartini, Nikolai; Hupa, Leena; Fatehi, Pedram

    2017-01-01

    Hot water hydrolysis process is commercially applied for treating wood chips prior to pulping or wood pellet production, while it produces hydrolysis liquor as a by-product. Since the hydrolysis liquor is dilute, the production of value-added materials from it would be challenging. In this study, acidification was proposed as a viable method to extract (1) furfural and acetic acid from hot water hydrolysis liquor and (2) lignin compounds from the liquor. The thermal properties of the precipitates made from the acidification of hydrolysis liquor confirmed the volatile characteristics of precipitates. Membrane dialysis was effective in removing inorganic salts associated with lignin compounds. The purified lignin compounds had a glass transition temperature (Tg) of 180-190 °C, and were thermally stable. The results confirmed that lignin compounds present in hot water hydrolysis liquor had different characteristics. The acidification of hydrolysis liquor primarily removed the volatile compounds from hydrolysis liquor. Based on these results, a process for producing purified lignin and precipitates of volatile compounds was proposed.

  16. Mechanism of the hydrolysis of 4-methylumbelliferyl-beta-D-glucoside by germinating and outgrowing spores of Bacillus species.

    Science.gov (United States)

    Setlow, B; Cabrera-Martinez, R-M; Setlow, P

    2004-01-01

    during spore outgrowth in the presence of beta-MUG. Deletion of the genes coding for BglA, BglH, BglC and BglD reduced beta-MUG hydrolysis by germinating and outgrowing spores of B. subtilis 168 at least 99.7%. Assay of glucosidases active on beta-MUG or beta-MUG-P in extracts of dormant and outgrowing spores of B. atrophaeus revealed no enzyme active on beta-MUG and one enzyme that comprised > or =90% of the phosphoglucosidase active on beta-MUG-P. Partial purification and amino-terminal sequence analysis of this phosphoglucosidase identified this enzyme as BglH. Generation of MU from beta-MUG by germinating and outgrowing spores of B. atrophaeus and B. subtilis is mediated by the PTS-driven uptake and phosphorylation of beta-MUG, followed by phosphoglucosidase action on the intracellular beta-MUG-P. The major phosphoglucosidase catalyzing MU generation from beta-MUG-P in spores of both species is probably BglH. This work provides new insight into the mechanism of uptake and hydrolysis of beta-MUG by germinating and outgrowing spores of Bacillus species, in particular B. atrophaeus. The research reported here provides a biological basis for a Rapid Readout Biological Indicator that is used to monitor the efficacy of ethylene oxide sterilization.

  17. Enteral Tube Feeding Nutritional Protein Hydrolysate Production Under Different Factors By Enzymatic Hydrolysis

    Directory of Open Access Journals (Sweden)

    Nguyen ThiQuynhHoa

    2015-01-01

    Full Text Available Abstract Hydrolysis of proteins involves the cleavage of peptide bonds to give peptides of varying sizes and amino acid composition. There are a number of types of hydrolysis enzymatic acid or alkali hydrolysis. Chemical hydrolysis is difficult to control and reduces the nutritional quality of products destroying L-form amino acids and producing toxic substances such as lysino-alanine. Enzymatic hydrolysis works without destructing amino acids and by avoiding the extreme temperatures and pH levels required for chemical hydrolysis the nutritional properties of the protein hydrolysates remain largely unaffected. In this research we investigate the fat removal and protein hydrolysis from pork meat to produce the enteral tube feeding nutritional protein hydrolysate for patient. Our results are as follows meat moisture 75.1 protein 22.6 lipid 1.71 ash 0.5 vitamin B1 1.384mg100g n hexantreatment at 80oCin 45 minutes and drying 30 minutes in 90oC.Viscosity of the hydrolysate is very low 2.240 0.092 cPand high degree of hydrolysis 31.390 0.138 . The final protein powder has balance nutritional components and acid amines low microorganisms which are safety for human consumption.

  18. Study of Enzymatic Hydrolysis of Dilute Acid Pretreated Coconut Husk

    Directory of Open Access Journals (Sweden)

    Rudy Agustriyanto

    2012-12-01

    Full Text Available Coconut husk is classified as complex lignocellulosic material that contains cellulose, hemicellulose, lignin, and some other extractive compounds. Cellulose from coconut husk can be used as fermentation substrate after enzymatic hydrolysis. In contrary, lignin content from the coconut husk will act as an inhibitor in this hydrolysis process. Therefore, a pretreatment process is needed to enhance the hydrolysis of cellulose. The objective of this research is to investigate the production of the glucose through dilute acid pretreatment and to obtain its optimum operating conditions. In this study, the pretreatment was done using dilute sulfuric acid in an autoclave reactor. The pretreatment condition were varied at 80°C, 100°C, 120°C and 0.9%, 1.2%, 1.5% for temperature and acid concentration respectively. The acid pretreated coconut husk was then hydrolyzed using commercial cellulase (celluclast and β-glucosidase (Novozyme 188. The hydrolysis time was 72 hours and the operating conditions were varied at several temperature and pH. From the experimental results it can be concluded that the delignification temperature variation has greater influence than the acid concentration. The optimum operating condition was obtained at pH 4 and 50°C which was pretreated at 100°C using 1.5% acid concentration. Copyright © 2012 by BCREC UNDIP. All rights reserved. (Selected Paper from International Conference on Chemical and Material Engineering (ICCME 2012Received: 28th September 2012, Revised: 2nd October 2012, Accepted: 4th October 2012[How to Cite: R. Agustriyanto, A. Fatmawati, Y. Liasari. (2012. Study of Enzymatic Hydrolysis of Dilute Acid Pretreated Coconut Husk. Bulletin of Chemical Reaction Engineering & Catalysis, 7(2: 137-141. doi:10.9767/bcrec.7.2.4046.137-141] [How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.2.4046.137-141 ] | View in 

  19. Lactose hydrolysis potential and thermal stability of commercial β-galactosidase in UHT and skimmed milk

    Directory of Open Access Journals (Sweden)

    Alessandra BOSSO

    2016-03-01

    Full Text Available Abstract The commercial enzyme (E.C. = 3.2.1.23 from Kluyveromyces lactis (liquid and Aspergillus oryzae(lyophilized was investigated for its hydrolysis potential in lactose substrate, UHT milk, and skimmed milk at different concentrations (0.7; 1.0 and 1.5%, pH values (5.0; 6.0; 6.5 and 7.0, and temperature (30; 35; 40 and 55 ºC. High hydrolysis rates were observed for the enzyme from K. lactis at pH 7.0 and 40 ºC, and from A. oryzae at pH 5.0 and 55 ºC. The enzyme from K. lactis showed significantly higher hydrolysis rates when compared to A. oryzae. The effect of temperature and β-galactosidase concentration on the lactose hydrolysis in UHT milk was higher than in skimmed milk, for all temperatures tested. With respect to the thermal stability, a decrease in hydrolysis rate was observed at pH 6.0 at 35 ºC for K. lactisenzyme, and at pH 6.0 at 55 ºC for the enzyme from A. oryzae. This study investigate the hydrolysis of β-galactosidase in UHT and skimmed milk. The knowledge about the characteristics of the β-galactosidase fromK. lactis and A. oryzae enables to use it most efficiently to control the enzyme concentration, temperature, and pH in many industrial processes and product formulations.

  20. Iron-catalyzed intermolecular cycloaddition of diazo surrogates with hexahydro-1,3,5-triazines.

    Science.gov (United States)

    Liu, Pei; Zhu, Chenghao; Xu, Guangyang; Sun, Jiangtao

    2017-09-26

    We report here an unprecedented iron-catalyzed cycloaddition reaction of diazo surrogates with hexahydro-1,3,5-triazines, providing five-membered heterocycles in moderate to high yields under mild reaction conditions. This cycloaddition features C-N and C-C bond formation using a cheap iron catalyst. Importantly, different to our former report on a gold-catalyzed system, both donor/donor and donor/acceptor diazo substrates are tolerated in this iron-catalyzed protocol.

  1. Recent advances in the ruthenium(ii)-catalyzed chelation-assisted C-H olefination of substituted aromatics, alkenes and heteroaromatics with alkenes via the deprotonation pathway.

    Science.gov (United States)

    Manikandan, Rajendran; Jeganmohan, Masilamani

    2017-08-08

    The transition-metal-catalyzed chelation-assisted alkenylation at the inert C-H bond of aromatics with alkenes is one of the efficient methods to synthesize substituted vinylarenes in a highly regio- and stereoselective manner. Palladium, rhodium and ruthenium complexes are frequently used as catalysts for this type of transformation. The present review describes the recent advances in the ruthenium-catalyzed chelation-assisted alkenylation at the C-H bond of aromatics, alkenes and heteroaromatics with alkenes via the deprotonation pathway. Several directing groups including 2-pyridyl, carbonyl, amidine, amide, amine, imidate, sulphonic acid, triazole, cyano, oxazolidinone and hydontoin are widely used in the reaction. The scope, limitation and mechanistic investigation of the alkenylation reactions are discussed elaborately. This feature article includes all the reported ruthenium-catalyzed alkenylation reactions via the deprotonation pathway until the end of March 2017.

  2. Hydrophilic bile salts enhance differential distribution of sphingomyelin and phosphatidylcholine between micellar and vesicular phases: potential implications for their effects in vivo

    NARCIS (Netherlands)

    Moschetta, A.; vanBerge-Henegouwen, G. P.; Portincasa, P.; Renooij, W. L.; Groen, A. K.; van Erpecum, K. J.

    2001-01-01

    The hepatocyte canalicular membrane outer leaflet contains both phosphatidylcholine (PC) and sphingomyelin (SM). Normally, PC is the exclusive phospholipid in bile. We examined effects of bile salt hydrophobicity on cytotoxicity and on differential SM and PC distribution between detergent-resistant

  3. Total Synthesis and Stereochemical Assignment of Delavatine A: Rh-Catalyzed Asymmetric Hydrogenation of Indene-Type Tetrasubstituted Olefins and Kinetic Resolution through Pd-Catalyzed Triflamide-Directed C-H Olefination.

    Science.gov (United States)

    Zhang, Zhongyin; Wang, Jinxin; Li, Jian; Yang, Fan; Liu, Guodu; Tang, Wenjun; He, Weiwei; Fu, Jian-Jun; Shen, Yun-Heng; Li, Ang; Zhang, Wei-Dong

    2017-04-19

    Delavatine A (1) is a structurally unusual isoquinoline alkaloid isolated from Incarvillea delavayi. The first and gram-scale total synthesis of 1 was accomplished in 13 steps (the longest linear sequence) from commercially available starting materials. We exploited an isoquinoline construction strategy and developed two reactions, namely Rh-catalyzed asymmetric hydrogenation of indene-type tetrasubstituted olefins and kinetic resolution of β-alkyl phenylethylamine derivatives through Pd-catalyzed triflamide-directed C-H olefination. The substrate scope of the first reaction covered unfunctionalized olefins and those containing polar functionalities such as sulfonamides. The kinetic resolution provided a collection of enantioenriched indane- and tetralin-based triflamides, including those bearing quaternary chiral centers. The selectivity factor (s) exceeded 100 for a number of substrates. These reactions enabled two different yet related approaches to a key intermediate 28 in excellent enantiopurity. In the synthesis, the triflamide served as not only an effective directing group for C-H bond activation but also a versatile functional group for further elaborations. The relative and absolute configurations of delavatine A were unambiguously assigned by the syntheses of the natural product and its three stereoisomers. Their cytotoxicity against a series of cancer cell lines was evaluated.

  4. Ligand-Controlled Chemoselective C(acyl)–O Bond vs C(aryl)–C Bond Activation of Aromatic Esters in Nickel Catalyzed C(sp2)–C(sp3) Cross-Couplings

    KAUST Repository

    Chatupheeraphat, Adisak

    2018-02-20

    A ligand-controlled and site-selective nickel catalyzed Suzuki-Miyaura cross-coupling reaction with aromatic esters and alkyl organoboron reagents as coupling partners was developed. This methodology provides a facile route for C(sp2)-C(sp3) bond formation in a straightforward fashion by successful suppression of the undesired β-hydride elimination process. By simply switching the phosphorus ligand, the ester substrates are converted into the alkylated arenes and ketone products, respectively. The utility of this newly developed protocol was demonstrated by its wide substrate scope, broad functional group tolerance and application in the synthesis of key intermediates for the synthesis of bioactive compounds. DFT studies on the oxidative addition step helped rationalizing this intriguing reaction chemoselectivity: whereas nickel complexes with bidentate ligands favor the C(aryl)-C bond cleavage in the oxidative addition step leading to the alkylated product via a decarbonylative process, nickel complexes with monodentate phosphorus ligands favor activation of the C(acyl)-O bond, which later generates the ketone product.

  5. SIMULTANEOUS PRETREATMENT OF LIGNOCELLULOSE AND HYDROLYSIS OF STARCH IN MIXTURES TO SUGARS

    Directory of Open Access Journals (Sweden)

    Hamzeh Hoseinpour

    2010-11-01

    Full Text Available Mixtures of starch and lignocelluloses are available in many industrial, agricultural, and municipal wastes and residuals. In this work, dilute sulfuric acid was used for simultaneous pretreatment of lignocellulose and hydrolysis of starch, to obtain a maximum amount of fermentable sugar after enzymatic hydrolysis with cellulase and β-glucosidase. The acid treatment was carried out at 70-150°C with 0-1% (v/v acid concentration and 5-15% (w/v solids concentration for 0-40 minutes. Under the optimum conditions, obtained at 130°C, 1% acid, and 7.5% solids loading for 30 min, the starch was almost completely converted to glucose. However, the acid treatment was not successful for efficient hydrolysis of pure cellulose. A mixture of pine softwood and potato as representatives of lignocellulosic and starch components, respectively, were treated at the optimum conditions for acid hydrolysis of starch. The dilute-acid treatment resulted in 1.2, 60.5, and 23.6% hydrolysis of glucan, xylan, and mannan of pine wood and 67% of potato starch to fermentable sugars. After the acid treatment, the solid residue of the mixture was subjected to enzymatic hydrolysis. The enzymatic hydrolysis under the optimum conditions resulted in conversion of 76% of the glucan in the treated softwood. Therefore, using acid treatment of the mixture is a promising process for pretreatment of wood in addition to the hydrolysis of starch.

  6. Cobalt-Catalyzed C(sp(2))-H Borylation: Mechanistic Insights Inspire Catalyst Design.

    Science.gov (United States)

    Obligacion, Jennifer V; Semproni, Scott P; Pappas, Iraklis; Chirik, Paul J

    2016-08-24

    A comprehensive study into the mechanism of bis(phosphino)pyridine (PNP) cobalt-catalyzed C-H borylation of 2,6-lutidine using B2Pin2 (Pin = pinacolate) has been conducted. The experimentally observed rate law, deuterium kinetic isotope effects, and identification of the catalyst resting state support turnover limiting C-H activation from a fully characterized cobalt(I) boryl intermediate. Monitoring the catalytic reaction as a function of time revealed that borylation of the 4-position of the pincer in the cobalt catalyst was faster than arene borylation. Cyclic voltammetry established the electron withdrawing influence of 4-BPin, which slows the rate of C-H oxidative addition and hence overall catalytic turnover. This mechanistic insight inspired the next generation of 4-substituted PNP cobalt catalysts with electron donating and sterically blocking methyl and pyrrolidinyl substituents that exhibited increased activity for the C-H borylation of unactivated arenes. The rationally designed catalysts promote effective turnover with stoichiometric quantities of arene substrate and B2Pin2. Kinetic studies on the improved catalyst, 4-(H)2BPin, established a change in turnover limiting step from C-H oxidative addition to C-B reductive elimination. The iridium congener of the optimized cobalt catalyst, 6-(H)2BPin, was prepared and crystallographically characterized and proved inactive for C-H borylation, a result of the high kinetic barrier for reductive elimination from octahedral Ir(III) complexes.

  7. Complementary Strategies for Directed C(sp3 )-H Functionalization: A Comparison of Transition-Metal-Catalyzed Activation, Hydrogen Atom Transfer, and Carbene/Nitrene Transfer.

    Science.gov (United States)

    Chu, John C K; Rovis, Tomislav

    2018-01-02

    The functionalization of C(sp 3 )-H bonds streamlines chemical synthesis by allowing the use of simple molecules and providing novel synthetic disconnections. Intensive recent efforts in the development of new reactions based on C-H functionalization have led to its wider adoption across a range of research areas. This Review discusses the strengths and weaknesses of three main approaches: transition-metal-catalyzed C-H activation, 1,n-hydrogen atom transfer, and transition-metal-catalyzed carbene/nitrene transfer, for the directed functionalization of unactivated C(sp 3 )-H bonds. For each strategy, the scope, the reactivity of different C-H bonds, the position of the reacting C-H bonds relative to the directing group, and stereochemical outcomes are illustrated with examples in the literature. The aim of this Review is to provide guidance for the use of C-H functionalization reactions and inspire future research in this area. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Amidines for versatile ruthenium(II)-catalyzed oxidative C-H activations with internal alkynes and acrylates.

    Science.gov (United States)

    Li, Jie; John, Michael; Ackermann, Lutz

    2014-04-25

    Cationic ruthenium complexes derived from KPF6 or AgOAc enabled efficient oxidative CH functionalizations on aryl and heteroaryl amidines. Thus, oxidative annulations of diversely decorated internal alkynes provided expedient access to 1-aminoisoquinolines, while catalyzed C-H activations with substituted acrylates gave rise to structurally novel 1-iminoisoindolines. The powerful ruthenium(II) catalysts displayed a remarkably high site-, regio- and, chemoselectivity. Therefore, the catalytic system proved tolerant of a variety of important electrophilic functional groups. Detailed mechanistic studies provided strong support for the cationic ruthenium(II) catalysts to operate by a facile, reversible C-H activation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Palladium-Catalyzed Reductive Insertion of Alcohols into Aryl Ether Bonds

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Meng [Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Gutiérrez, Oliver Y. [Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Camaioni, Donald M. [Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Lercher, Johannes A. [Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Department of Chemistry and Catalysis Research Institute, TU München, Lichtenbergstrasse 4 85748 Garching Germany

    2018-03-06

    Pd/C catalyzes C-O bond cleavage of aryl ethers (diphenyl ether and cyclohexyl phenyl ether) by methanol in H2. The aromatic C-O bond is cleaved by reductive methanolysis, which is initiated by Pd-catalyzed partial hydrogenation of one phenyl ring to form an enol ether. The enol ether reacts rapidly with methanol to form a ketal, which generates methoxycyclohexene by eliminating phenol or an alkanol. Subsequent hydrogenation leads to methoxycyclohexane.

  10. Effect and Modeling of Glucose Inhibition and In Situ Glucose Removal During Enzymatic Hydrolysis of Pretreated Wheat Straw

    DEFF Research Database (Denmark)

    Andric, Pavle; Meyer, Anne S.; Jensen, Peter Arendt

    2010-01-01

    The enzymatic hydrolysis of lignocellulosic biomass is known to be product-inhibited by glucose. In this study, the effects on cellulolytic glucose yields of glucose inhibition and in situ glucose removal were examined and modeled during extended treatment of heat-pretreated wheat straw......, during 96 h of reaction. When glucose was removed by dialysis during the enzymatic hydrolysis, the cellulose conversion rates and glucose yields increased. In fact, with dialytic in situ glucose removal, the rate of enzyme-catalyzed glucose release during 48-72 h of reaction recovered from 20......-40% to become approximate to 70% of the rate recorded during 6-24 h of reaction. Although Michaelis-Menten kinetics do not suffice to model the kinetics of the complex multi-enzymatic degradation of cellulose, the data for the glucose inhibition were surprisingly well described by simple Michaelis...

  11. Lipase catalyzed ester synthesis for food processing industries

    Directory of Open Access Journals (Sweden)

    Aravindan Rajendran

    2009-02-01

    Full Text Available Lipases are one of the most important industrial biocatalyst which catalyzes the hydrolysis of lipids. It can also reverse the reaction at minimum water activity. Because of this pliable nature, it is widely exploited to catalyze the diverse bioconversion reactions, such as hydrolysis, esterification, interesterification, alcoholysis, acidolysis and aminolysis. The property to synthesize the esters from the fatty acids and glycerol promotes its use in various ester synthesis. The esters synthesized by lipase finds applications in numerous fields such as biodiesel production, resolution of the recemic drugs, fat and lipid modification, flavour synthesis, synthesis of enantiopure pharmaceuticals and nutraceuticals. It plays a crucial role in the food processing industries since the process is unaffected by the unwanted side products. Lipase modifications such as the surfactant coating, molecular imprinting to suit for the non-aqueous ester synthesis have also been reported. This review deals with lipase catalyzed ester synthesis, esterification strategies, optimum conditions and their applications in food processing industries.Lipases são catalizadores industriais dos mais importantes, os quais catalizam a hidrólise de lipídeos. Também podem reverter a reação a um mínimo de atividade de água. Devido sua natureza flexível, é amplamente explorada para catalizar uma diversidade de reações de bioconversão como hidrólise, esterificação, interesterificação, alcoólise, acidólise e aminólise. A propriedade de síntese de esteres a partir de ácidos graxos e glicerol promoveu seu uso em várias sínteses de esteres. Os esteres sintetizados por lipases encontram aplicação em numerosos campos como a produção de biodiesel, resolução de drogas racêmicas, modificação de gorduras e lipídios, sintese de aromas, síntese de produtos farmacêuticos enantiopuro e nutracêuticos. As lipases possuem um papel crucial nas indústrias de

  12. Hydrolysis of polyacrylamide containing associative hydrophobic groups: effect of the degree of hydrolysis and ionic strength on the viscosity in aqueous medium

    International Nuclear Information System (INIS)

    Lima, Bruna V. de; Vidal, Rosangela R.L.; Reis, Jeanne H.C. dos; Balaban, Rosangela de C.

    2009-01-01

    The HAPAM-10N polymer (hydrophobically modified and partially hydrolyzed polyacrylamide) was obtained by partial hydrolysis of HAPAM (hydrophobically modified polyacrylamide) precursor containing very low amount of hydrophobic groups (0.75%) in 0.1 M NaCl and 0.25 M NaOH aqueous solutions, at 40 deg C for 10 min. Hydrolysis degree of 44.64 % was obtained by 13 C NMR. The viscosity of polymers solutions was evaluated as a function of polymer concentration, ionic strength and temperature, at constant shear rate. The viscosity of HAPAM solutions increased with polymer concentration, however, it did not change significantly with the increase of ionic strength, and decreased with the temperature enhancement. The viscosity of HAPAM-10N solutions increased significantly in distilled water, due to electrostatic repulsions among carboxylate groups. However, with the increase of polymer concentration, ionic strength and temperature, it was not observed a significant increase of viscosity, probably due to the low amount of hydrophobic groups and high hydrolysis degree. (author)

  13. Optimization of enzymatic hydrolysis of guar gum using response surface methodology.

    Science.gov (United States)

    Mudgil, Deepak; Barak, Sheweta; Khatkar, B S

    2014-08-01

    Guar gum is a polysaccharide obtained from guar seed endosperm portion. Enzymatically hydrolyzed guar gum is low in viscosity and has several health benefits as dietary fiber. In this study, response surface methodology was used to determine the optimum conditions for hydrolysis that give minimum viscosity of guar gum. Central composite was employed to investigate the effects of pH (3-7), temperature (20-60 °C), reaction time (1-5 h) and cellulase concentration (0.25-1.25 mg/g) on viscosity during enzymatic hydrolysis of guar (Cyamopsis tetragonolobus) gum. A second order polynomial model was developed for viscosity using regression analysis. Results revealed statistical significance of model as evidenced from high value of coefficient of determination (R(2) = 0.9472) and P < 0.05. Viscosity was primarily affected by cellulase concentration, pH and hydrolysis time. Maximum viscosity reduction was obtained when pH, temperature, hydrolysis time and cellulase concentration were 6, 50 °C, 4 h and 1.00 mg/g, respectively. The study is important in optimizing the enzymatic process for hydrolysis of guar gum as potential source of soluble dietary fiber for human health benefits.

  14. Hydrolysis of TBF and TiAP in presence of zirconium

    International Nuclear Information System (INIS)

    Vladimirova, M.V.; Kulikov, I.A.; Kuprij, A.A.

    1992-01-01

    Acid hydrolysis of organic solutions of tributyl phosphate (TBP) and tri-iso-amylphosphate (TiAP) in n-paraffin diluent in the presence of zirconium (0.025-0.1 mole/l) at nitric acid concentration of 0.3-1 mole/l is studied. Hydrolysis of extractants in a two-phase system, modelling conditions of spent fuel reprocessing and consisting of 1.1 mole/l TAP, 3 mole/l nitric acid at zirconium concentration in water phase 0.05-0.11 mole/l, at water-organic phase ratio 10:1 and at 60 deg C is also studied. Constants of TAP hydrolysis in organic and water phases are determined. Mechanism of increasing the TAP hydrolysis rate in zirconium presence is discussed. 5 refs., 2 figs., 5 tabs

  15. Identification of Sphingomyelinase on the Surface of Chlamydia pneumoniae: Possible Role in the Entry into Its Host Cells

    Directory of Open Access Journals (Sweden)

    Tuula A. Peñate Medina

    2014-01-01

    Full Text Available We have recently suggested a novel mechanism, autoendocytosis, for the entry of certain microbes into their hosts, with a key role played by the sphingomyelinase-catalyzed topical conversion of sphingomyelin to ceramide, the differences in the biophysical properties of these two lipids providing the driving force. The only requirement for such microbes to utilize this mechanism is that they should have a catalytically active SMase on their outer surface while the target cells should expose sphingomyelin in the external leaflet of their plasma membrane. In pursuit of possible microbial candidates, which could utilize this putative mechanism, we conducted a sequence similarity search for SMase. Because of the intriguing cellular and biochemical characteristics of the poorly understood entry of Chlamydia into its host cells these microbes were of particular interest. SMase activity was measured in vitro from isolated C. pneumoniae elementary bodies (EB and in the lysate from E. coli cells transfected with a plasmid expressing CPn0300 protein having sequence similarity to SMase. Finally, pretreatment of host cells with exogenous SMase resulting in loss plasma membrane sphingomyelin attenuated attachment of EB.

  16. Hydrolysis of surimi wastewater for production of transglutaminase by Enterobacter sp. C2361 and Providencia sp. C1112.

    Science.gov (United States)

    H-Kittikun, Aran; Bourneow, Chaiwut; Benjakul, Soottawat

    2012-12-01

    Surimi wastewater (SWW) is an industrial wastewater, released during the washing step of surimi preparation from minced fish, that causes environmental problem. In this study, SWW produced from ornate threadfin bream (Nemipterus hexodon) was hydrolysed and used to cultivate Enterobacter sp. C2361 and Providencia sp. C1112 for the production of microbial transglutaminase (MTGase, EC 2.3.2.13). The SWW was repeatedly used to wash the fish mince that gained a final protein content of 3.20% (w/v). The commercial protease, Delvolase was the most appropriate protease used to produce fish protein hydrolysate (FPH) from SWW. The FPH at 40% degree of hydrolysis was used instead of a peptone portion in the SPY medium (3.0% starch, 2.0% peptone, 0.2% yeast extract, 0.2% MgSO(4), 0.2% K(2)HPO(4) and 0.2% KH(2)HPO(4), pH 7.0) to cultivate the tested strains at 37°C, shaking speed at 150rpm. Providencia sp. C1112 produced higher MTGase activity (1.78±0.05U/ml) than Streptoverticillium mobaraense (1.61±0.02U/ml) at 18h of cultivation in FPH medium. On the other hand, the Enterobacter sp. C2361 produced lower MTGase activity (1.18±0.03U/ml). Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Solvable Catalyzed Birth-Death-Exchange Competition Model of Three Species

    International Nuclear Information System (INIS)

    Wang Haifeng; Gao Yan; Zhang Heng; Lin Zhenquan

    2009-01-01

    A competition model of three species in exchange-driven aggregation growth is proposed. In the model, three distinct aggregates grow by exchange of monomers and in parallel, birth of species A is catalyzed by species B and death of species A is catalyzed by species C. The rates for both catalysis processes are proportional to kj ν and kj ω respectively, where ν(Ω) is a parameter reflecting the dependence of the catalysis reaction rate of birth (death) on the catalyst aggregate's size. The kinetic evolution behaviors of the three species are investigated by the rate equation approach based on the mean-field theory. The form of the aggregate size distribution of A-species a k (t) is found to be dependent crucially on the two catalysis rate kernel parameters. The results show that (i) in case of μ ≤ 0, the form of a k (t) mainly depends on the competition between self-exchange of species A and species-C-catalyzed death of species A; (ii) in case of ν > 0, the form of a k (t) mainly depends on the competition between species-B-catalyzed birth of species A and species-C-catalyzed death of species A. (interdisciplinary physics and related areas of science and technology)

  18. Production of Biodiesel from High Acid Value Waste Cooking Oil Using an Optimized Lipase Enzyme/Acid-Catalyzed Hybrid Process

    Directory of Open Access Journals (Sweden)

    N. Saifuddin

    2009-01-01

    Full Text Available The present study is aimed at developing an enzymatic/acid-catalyzed hybrid process for biodiesel production using waste cooking oil with high acid value (poor quality as feedstock. Tuned enzyme was prepared using a rapid drying technique of microwave dehydration (time required around 15 minutes. Further enhancement was achieved by three phase partitioning (TPP method. The results on the lipase enzyme which was subjected to pH tuning and TPP, indicated remarkable increase in the initial rate of transesterification by 3.8 times. Microwave irradiation was found to increase the initial reaction rates by further 1.6 times, hence giving a combined increase in activity of about 5.4 times. The optimized enzyme was used for hydrolysis and 88% of the oil taken initially was hydrolyzed by the lipase. The hydrolysate was further used in acid-catalyzed esterification for biodiesel production. By using a feedstock to methanol molar ratio of 1:15 and a sulphuric acid concentration of 2.5%, a biodiesel conversion of 88% was obtained at 50 °C for an hour reaction time. This hybrid process may open a way for biodiesel production using unrefined and used oil with high acid value as feedstock.

  19. Reactor design for minimizing product inhibition during enzymatic lignocellulose hydrolysis: I. Significance and mechanism of cellobiose and glucose inhibition on cellulolytic enzymes

    DEFF Research Database (Denmark)

    Andric, Pavle; Meyer, Anne S.; Jensen, Peter Arendt

    2010-01-01

    Achievement of efficient enzymatic degradation of cellulose to glucose is one of the main prerequisites and one of the main challenges in the biological conversion of lignocellulosic biomass to liquid fuels and other valuable products. The specific inhibitory interferences by cellobiose and glucose...... on enzyme-catalyzed cellulose hydrolysis reactions impose significant limitations on the efficiency of lignocellulose conversion especially at high-biomass dry matter conditions. To provide the base for selecting the optimal reactor conditions, this paper reviews the reaction kinetics, mechanisms......, and significance of this product inhibition, notably the cellobiose and glucose inhibition, on enzymatic cellulose hydrolysis. Particular emphasis is put on the distinct complexity of cellulose as a substrate, the multi-enzymatic nature of the cellulolytic degradation, and the particular features of cellulase...

  20. Synthesis of supermacroporous cryogel for bioreactors continuous starch hydrolysis.

    Science.gov (United States)

    Guilherme, Ederson Paulo Xavier; de Oliveira, Jocilane Pereira; de Carvalho, Lorendane Millena; Brandi, Igor Viana; Santos, Sérgio Henrique Sousa; de Carvalho, Gleidson Giordano Pinto; Cota, Junio; Mara Aparecida de Carvalho, Bruna

    2017-11-01

    A bioreactor was built by means of immobilizing alpha-amylase from Aspergillus oryzae by encapsulation, through cryopolymerization of acrylamide monomers for the continuous starch hydrolysis. The starch hydrolysis was evaluated regarding pH, the concentration of immobilized amylase on cryogel, the concentration of starch solution and temperature. The maximum value for starch hydrolysis was achieved at pH 5.0, concentration of immobilized enzyme 111.44 mg amylase /g cryogel , concentration of starch solution 45 g/L and temperature of 35°C. The immobilized enzyme showed a conversion ratio ranging from 68.2 to 97.37%, depending on the pH and temperature employed. Thus, our results suggest that the alpha-amylase from A. oryzae immobilized on cryogel monoliths represents a potential process for industrial production of maltose from starch hydrolysis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Palladium-Catalyzed ortho-Olefination of Phenyl Acetic and Phenyl Propylacetic Esters via C-H Bond Activation.

    Science.gov (United States)

    Hu, Jundie; Guan, Mingyu; Han, Jian; Huang, Zhi-Bin; Shi, Da-Qing; Zhao, Yingsheng

    2015-08-21

    A highly regioselective palladium-catalyzed ester-directed ortho-olefination of phenyl acetic and propionic esters with olefins via C-H bond activation has been developed. A wide variety of phenyl acetic and propionic esters were tolerated in this transformation, affording the corresponding olefinated aromatic compounds. The ortho-olefination of heterocyclic acetic and propionic esters also took place smoothly giving the products in good yields, thus proving the potential utility of this protocol in synthetic chemistry.

  2. Sphingomyelinase Activity of Trichomonas vaginalis Extract and Subfractions

    Directory of Open Access Journals (Sweden)

    Francisco González-Salazar

    2013-01-01

    Full Text Available Trichomoniasis is one of the most common acute sexually transmitted curable diseases, and it is disseminated worldwide generating more than 170 million cases annually. Trichomonas vaginalis is the parasite that causes trichomoniasis and has the ability to destroy cell monolayers of the vaginal mucosa in vitro. Sphingomyelinases (SMase are enzymes that catalyze the hydrolysis of sphingomyelin into ceramide and phosphorylcholine. Ceramide appears to be a second messenger lipid in programmed apoptosis, cell differentiation, and cell proliferation. Sphingomyelinase is probably a major source of ceramide in cells. Signal transduction mediated by ceramide leads cells to produce cytokine induced apoptosis during several inflammatory responses. SMase are also relevant toxins in several microorganisms. The main objective of this research is to identify SMase activity of T. vaginalis in the total extract (TE, P30, and S30 subfractions from brooked trophozoites. It was found that these fractions of T. vaginalis have SMase activity, which comes principally from P30 subfraction and was mainly type C. Enzymatic activity of SMase increased linearly with time and is pH dependent with two peaks by pH 5.5 and pH 7.5. The addition of manganese to the reaction mixture increased the SMase activity by 1.97.

  3. Combined wet oxidation and alkaline hydrolysis of polyvinylchloride

    DEFF Research Database (Denmark)

    Sørensen, E.; Bjerre, A.B.

    1992-01-01

    In view of the widespread aversion to burning polyvinylchloride (PVC) together with municipal waste, we have attempted an alternative approach to its decomposition. This paper describes a combined wet oxidation/alkaline hydrolysis yielding water soluble, biodegradable products. Experiments were...... carried out at temperatures from 180-260 degree C and reaction times of 8-24 min. The chloride liberated provides information on the rate constants. Considering the measured Cl- and Chemical Oxygen Demand (COD) values, we find hydrolysis and oxidation processes to be interdependent. The main products...

  4. Importance of cellulase cocktails favoring hydrolysis of cellulose.

    Science.gov (United States)

    Victoria, Juliet; Odaneth, Annamma; Lali, Arvind

    2017-07-03

    Depolymerization of lignocellulosic biomass is catalyzed by groups of enzymes whose action is influenced by substrate features and the composition of cellulase preparation. Cellulases contain a mixture of variety of enzymes, whose proportions dictate the saccharification of biomass. In the current study, four cellulase preparation varying in their composition were used to hydrolyze two types of alkali-treated biomass (aqueous ammonia-treated rice straw and sodium hydroxide-treated rice straw) to study the effect on catalytic rate, saccharification yields, and sugar release profile. We found that substrate features affected the extent of saccharification but had minimal effect on the sugar release pattern. In addition, complete hydrolysis to glucose was observed with enzyme preparation having at least a cellobiase units (CBU)/carboxymethyl cellulose (CMC) ratio (>0.15), while a modified enzyme ratio can be used for oligosaccharide synthesis. Thus, cellulase preparation with defined ratios of the three main enzymes can improve the saccharification which is of utmost importance in defining the success of lignocellulose-based economies.

  5. From ketones to esters by a Cu-catalyzed highly selective C(CO)-C(alkyl) bond cleavage: aerobic oxidation and oxygenation with air.

    Science.gov (United States)

    Huang, Xiaoqiang; Li, Xinyao; Zou, Miancheng; Song, Song; Tang, Conghui; Yuan, Yizhi; Jiao, Ning

    2014-10-22

    The Cu-catalyzed aerobic oxidative esterification of simple ketones via C-C bond cleavage has been developed. Varieties of common ketones, even inactive aryl long-chain alkyl ketones, are selectively converted into esters. The reaction tolerates a wide range of alcohols, including primary and secondary alcohols, chiral alcohols with retention of the configuration, electron-deficient phenols, as well as various natural alcohols. The usage of inexpensive copper catalyst, broad substrate scope, and neutral and open air conditions make this protocol very practical. (18)O labeling experiments reveal that oxygenation occurs during this transformation. Preliminary mechanism studies indicate that two novel pathways are mainly involved in this process.

  6. Platinum-Catalyzed Terminal-Selective C(sp3)–H Oxidation of Aliphatic Amines

    Science.gov (United States)

    Lee, Melissa; Sanford, Melanie S.

    2016-01-01

    This paper describes the terminal-selective Pt-catalyzed C(sp3)–H oxidation of aliphatic amines without the requirement for directing groups. CuCl2 is employed as a stoichiometric oxidant, and the reactions proceed in high yield at Pt loadings as low as 1 mol %. These transformations are conducted in the presence of sulfuric acid, which reacts with the amine substrates in situ to form ammonium salts. We propose that protonation of the amine serves at least three important roles: (i) it renders the substrates soluble in the aqueous reaction medium; (ii) it limits binding of the amine nitrogen to Pt or Cu; and (ii) it electronically deactivates the C–H bonds proximal to the nitrogen center. We demonstrate that this strategy is effective for the terminal-selective C(sp3)–H oxidation of a variety of primary, secondary and tertiary amines. PMID:26439251

  7. Pd-Catalyzed Acetoxylation of γ-C(sp3)-H Bonds of Amines Directed by a Removable Bts-Protecting Group.

    Science.gov (United States)

    Zheng, Yong; Song, Weibin; Zhu, Yefu; Wei, Bole; Xuan, Lijiang

    2018-02-16

    Pd-catalyzed acetoxylation of γ-C(sp 3 )-H bonds directed by Bts-protected amines using inexpensive PhI(OAc) 2 as oxidant is reported. The Bts-protecting group is easily introduced and removed under mild conditions. This protocol provides an important strategy for the construction of γ-hydroxyl amine derivatives.

  8. Ni-polymer nanogel hybrid particles: A new strategy for hydrogen production from the hydrolysis of dimethylamine-borane and sodium borohydride

    International Nuclear Information System (INIS)

    Cai, Haokun; Liu, Liping; Chen, Qiang; Lu, Ping; Dong, Jian

    2016-01-01

    Efficient non-precious metal catalysts are crucial for hydrogen production from borohydride compounds in aqueous media via hydrogen atoms in water. A method for preparing magnetic polymer nanoparticles is developed in this study based on the chemical deposition of nickel onto hydrophilic polymer nanogels. High-resolution transmission electron microscopic and XPS analyses show that Ni exists mainly in the form of NiO in nanogels. Excellent catalytic activities of the nanoparticles are demonstrated for hydrogen generation from the hydrolysis of dimethylamine-borane and sodium borohydride in which the initial TOF (turn-over frequencies) are 376 and 1919 h"−"1, respectively. Kinetic studies also reveal an Arrhenius activation energy of 50.96 kJ mol"−"1 for the hydrolysis of dimethylamine-borane and 47.82 kJ mol"−"1 for the hydrolysis of sodium borohydride, which are lower than those catalyzed by Ru metal. Excellent reusability and the use of water for hydrogen production from dimethylamine-borane provide the additional benefit of using a hybrid catalyst. The principle illustrated in the present study offers a new strategy to explore polymer-transition metal hybrid particles for hydrogen energy technology. - Highlights: • Electroless Ni plating on polymer nanogels generated recyclable catalysts. • The Ni particles proved efficient for H_2 production from borohydride compounds. • The catalysts have lower activation energies than Ru for the hydrolysis. • Borohydride hydrolysis is more beneficial than dehydrogenation in organic solvent.

  9. Lactose hydrolysis by free and fibre-entrapped β-galactosidase from Streptococcus thermophilus

    Directory of Open Access Journals (Sweden)

    Zhennai Yang

    1993-09-01

    Full Text Available To study lactose hydrolysis by β-galactosidase, this enzyme was produced from Streptococcus thermophilus strain 11F and partially purified by acetone and ammonium sulphate fractionation, and ion exchange chromatography on a Q Sepharose FF column. Lactose hydrolysis by the enzyme was affected by lactose concentrations, sugars and milk proteins. The maximum extent of lactose hydrolysis in buffer was obtained with a 15% lactose concentration. Addition of 2% of lactose, glucose, galactose or sucrose in milk inhibited the enzymatic hydrolysis. The enzyme was activated by bovine serum albumin and a combination of αs-casein and β-casein. Of the casein fractions, the principal fraction, αs-casein, was less effective than β-casein and κ-casein. The fibre entrapped enzyme had a temperature optimum of 57°C, and a pH optimum from 7.5 to at least 9.0 with O-nitrophenyl-β-D-galactopyranoside as substrate. By recycling with whey and skim milk through a jacketed glass column (1.6 cm x 30 cm loaded with fibre-entrapped enzyme at 55°C, a lactose hydrolysis of 49.5% and 47.9% was achieved in 11 h and 7 h respectively.

  10. Sphingomyelin functions as a novel receptor for Helicobacter pylori VacA.

    Directory of Open Access Journals (Sweden)

    Vijay R Gupta

    2008-05-01

    Full Text Available The vacuolating cytotoxin (VacA of the gastric pathogen Helicobacter pylori binds and enters epithelial cells, ultimately resulting in cellular vacuolation. Several host factors have been reported to be important for VacA function, but none of these have been demonstrated to be essential for toxin binding to the plasma membrane. Thus, the identity of cell surface receptors critical for both toxin binding and function has remained elusive. Here, we identify VacA as the first bacterial virulence factor that exploits the important plasma membrane sphingolipid, sphingomyelin (SM, as a cellular receptor. Depletion of plasma membrane SM with sphingomyelinase inhibited VacA-mediated vacuolation and significantly reduced the sensitivity of HeLa cells, as well as several other cell lines, to VacA. Further analysis revealed that SM is critical for VacA interactions with the plasma membrane. Restoring plasma membrane SM in cells previously depleted of SM was sufficient to rescue both toxin vacuolation activity and plasma membrane binding. VacA association with detergent-resistant membranes was inhibited in cells pretreated with SMase C, indicating the importance of SM for VacA association with lipid raft microdomains. Finally, VacA bound to SM in an in vitro ELISA assay in a manner competitively inhibited by lysenin, a known SM-binding protein. Our results suggest a model where VacA may exploit the capacity of SM to preferentially partition into lipid rafts in order to access the raft-associated cellular machinery previously shown to be required for toxin entry into host cells.

  11. Vitamin C. Biosynthesis, recycling and degradation in mammals.

    Science.gov (United States)

    Linster, Carole L; Van Schaftingen, Emile

    2007-01-01

    Vitamin C, a reducing agent and antioxidant, is a cofactor in reactions catalyzed by Cu(+)-dependent monooxygenases and Fe(2+)-dependent dioxygenases. It is synthesized, in vertebrates having this capacity, from d-glucuronate. The latter is formed through direct hydrolysis of uridine diphosphate (UDP)-glucuronate by enzyme(s) bound to the endoplasmic reticulum membrane, sharing many properties with, and most likely identical to, UDP-glucuronosyltransferases. Non-glucuronidable xenobiotics (aminopyrine, metyrapone, chloretone and others) stimulate the enzymatic hydrolysis of UDP-glucuronate, accounting for their effect to increase vitamin C formation in vivo. Glucuronate is converted to l-gulonate by aldehyde reductase, an enzyme of the aldo-keto reductase superfamily. l-Gulonate is converted to l-gulonolactone by a lactonase identified as SMP30 or regucalcin, whose absence in mice leads to vitamin C deficiency. The last step in the pathway of vitamin C synthesis is the oxidation of l-gulonolactone to l-ascorbic acid by l-gulonolactone oxidase, an enzyme associated with the endoplasmic reticulum membrane and deficient in man, guinea pig and other species due to mutations in its gene. Another fate of glucuronate is its conversion to d-xylulose in a five-step pathway, the pentose pathway, involving identified oxidoreductases and an unknown decarboxylase. Semidehydroascorbate, a major oxidation product of vitamin C, is reconverted to ascorbate in the cytosol by cytochrome b(5) reductase and thioredoxin reductase in reactions involving NADH and NADPH, respectively. Transmembrane electron transfer systems using ascorbate or NADH as electron donors serve to reduce semidehydroascorbate present in neuroendocrine secretory vesicles and in the extracellular medium. Dehydroascorbate, the fully oxidized form of vitamin C, is reduced spontaneously by glutathione, as well as enzymatically in reactions using glutathione or NADPH. The degradation of vitamin C in mammals is

  12. Comparison of sulfuric and hydrochloric acids as catalysts in hydrolysis of Kappaphycus alvarezii (cottonii).

    Science.gov (United States)

    Meinita, Maria Dyah Nur; Hong, Yong-Ki; Jeong, Gwi-Taek

    2012-01-01

    In this study, hydrolysis of marine algal biomass Kappaphhycus alvarezii using two different acid catalysts was examined with the goal of identifying optimal reaction conditions for the formation of sugars and by-products. K. alvarezii were hydrolyzed by autoclave using sulfuric acid or hydrochloric acid as catalyst with different acid concentrations (0.1-1.0 M), substrate concentrations (1.0-13.5%), hydrolysis time (10-90 min) and hydrolysis temperatures (100-130 (°)C). A difference in galactose, glucose, reducing sugar and total sugar content was observed under the different hydrolysis conditions. Different by-product compounds such as 5-hydroxymethylfurfural and levulinic acid were also observed under the different reaction conditions. The optimal conditions for hydrolysis were achieved at a sulfuric acid concentration, temperature and reaction time of 0.2 M, 130 °C and 15 min, respectively. These results may provide useful information for the development of more efficient systems for biofuel production from marine biomass.

  13. Hydrocarbon formation mechanism during uranium monocarbide hydrolysis

    International Nuclear Information System (INIS)

    Ermolaev, M.I.; Tishchenko, G.V.

    1979-01-01

    The hydrolysis of uranium monocarbide in oxidative media and in the presence of excessive hydrogen in statu nascendi has been investigated. It was found that oxydants promote the formation of elementary carbon, while in the presence of hydrogen the yield of light C-C hydrocarbons increases. EPR data confirm the radical mechanism of hydrocarbons formation during the decomposition of uranium monocarbide

  14. Optimization of reaction conditions for enzymatic viscosity reduction and hydrolysis of wheat arabinoxylan in an industrial ethanol fermentation residue

    DEFF Research Database (Denmark)

    Sørensen, H.R.; Pedersen, S.; Meyer, Anne Boye Strunge

    2006-01-01

    with a 50:50 mixture of an enzyme preparation from Humicola insolens, Ultraflo L, and a cellulolytic enzyme preparation from Trichoderma reesei, Celluclast 1.5 L. This enzyme mixture was previously shown to exhibit a synergistic action on arabinoxylan degradation. The viscosity of vinasse decreased...... of enzyme-catalyzed hydrolysis of arabinoxylan, beta-glucan, and cellulose. In designed response surface experiments, the optimal enzyme reaction conditions with respect to pH and temperature of the vinasse, the vinasse supernatant (mainly soluble material), and the vinasse sediment (mainly insoluble...

  15. Effect of acid hydrolysis on morphology, structure and digestion property of starch from Cynanchum auriculatum Royle ex Wight.

    Science.gov (United States)

    Wang, Xingchi; Wen, Fanting; Zhang, Shurong; Shen, Ruru; Jiang, Wei; Liu, Jun

    2017-03-01

    Effect of acid hydrolysis on the morphology, structure and digestion property of starch from Cynanchum auriculatum Royle ex Wight was investigated in this study. The hydrolysis degree of C. auriculatum starch rapidly increased to 63.69% after 4days and reached 78.67% at the end of 9days. Morphology observation showed that the starch granules remained intact during the first 4days of hydrolysis. However, serious erosion phenomenon was observed after 5days and starch granules completely fell into pieces after 7days. During acid hydrolysis process, the crystal type of hydrolyzed starch changed from original C B -type to final A-type. Small-angle X-ray scattering patterns showed the semi-crystalline growth rings started to be hydrolyzed after 4days. The proportions of single helix and amorphous components as well as amylose content in starch gradually decreased, whereas the proportion of double helix components continuously increased during acid hydrolysis. However, the contents of rapidly digestible starch, slowly digestible starch and resistant starch were almost constant during acid hydrolysis process, indicating the in vitro digestion property of C. auriculatum starch was not affected by acid hydrolysis. Our results provided novel information on the inner structure of C. auriculatum starch granules. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Sphingomyelin in High-Density Lipoproteins: Structural Role and Biological Function

    Directory of Open Access Journals (Sweden)

    Jesús Osada

    2013-04-01

    Full Text Available High-density lipoprotein (HDL levels are an inverse risk factor for cardiovascular diseases, and sphingomyelin (SM is the second most abundant phospholipid component and the major sphingolipid in HDL. Considering the marked presence of SM, the present review has focused on the current knowledge about this phospholipid by addressing its variable distribution among HDL lipoparticles, how they acquire this phospholipid, and the important role that SM plays in regulating their fluidity and cholesterol efflux from different cells. In addition, plasma enzymes involved in HDL metabolism such as lecithin–cholesterol acyltransferase or phospholipid transfer protein are inhibited by HDL SM content. Likewise, HDL SM levels are influenced by dietary maneuvers (source of protein or fat, drugs (statins or diuretics and modified in diseases such as diabetes, renal failure or Niemann–Pick disease. Furthermore, increased levels of HDL SM have been shown to be an inverse risk factor for coronary heart disease. The complexity of SM species, described using new lipidomic methodologies, and their distribution in different HDL particles under many experimental conditions are promising avenues for further research in the future.

  17. Recent research progress with phospholipase C from Bacillus cereus.

    Science.gov (United States)

    Lyu, Yan; Ye, Lidan; Xu, Jun; Yang, Xiaohong; Chen, Weiwei; Yu, Hongwei

    2016-01-01

    Phospholipase C (PLC) catalyzes the hydrolysis of phospholipids to produce phosphate monoesters and diacylglycerol. It has many applications in the enzymatic degumming of plant oils. PLC Bc , a bacterial PLC from Bacillus cereus, is an optimal choice for this activity in terms of its wide substrate spectrum, high activity, and approved safety. Unfortunately, its large-scale production and reliable high-throughput screening of PLC Bc remain challenging. Herein, we summarize the research progress regarding PLC Bc with emphasis on the screening methods, expression systems, catalytic mechanisms and inhibitor of PLC Bc . This review hopefully will inspire new achievements in related areas, to promote the sustainable development of PLC Bc and its application.

  18. Desaturation reactions catalyzed by soluble methane monooxygenase.

    Science.gov (United States)

    Jin, Y; Lipscomb, J D

    2001-09-01

    Soluble methane monooxygenase (MMO) is shown to be capable of catalyzing desaturation reactions in addition to the usual hydroxylation and epoxidation reactions. Dehydrogenated products are generated from MMO-catalyzed oxidation of certain substrates including ethylbenzene and cyclohexadienes. In the reaction of ethylbenzene, desaturation of ethyl C-H occurred along with the conventional hydroxvlations of ethyl and phenyl C-Hs. As a result, styrene is formed together with ethylphenols and phenylethanols. Similarly, when 1,3- and 1,4-cyclohexadienes were used as substrates, benzene was detected as a product in addition to the corresponding alcohols and epoxides. In all cases, reaction conditions were found to significantly affect the distribution among the different products. This new activity of MMO is postulated to be associated with the chemical properties of the substrates rather than fundamental changes in the nature of the oxygen and C-H activation chemistries. The formation of the desaturated products is rationalized by formation of a substrate cationic intermediate, possibly via a radical precursor. The cationic species is then proposed to partition between recombination (alcohol formation) and elimination (alkene production) pathways. This novel function of MMO indicates close mechanistic kinship between the hydroxylation and desaturation reactions catalyzed by the nonheme diiron clusters.

  19. Effects of cations and cholesterol with sphingomyelin membranes investigated by high-resolution broadband sum frequency vibrational spectroscopy

    Science.gov (United States)

    Zhang, Zhen; Feng, Rong-juan; Li, Yi-yi; Liu, Ming-hua; Guo, Yuan

    2017-08-01

    Sphingomyelin(SM) is specifically enriched in the plasma membrane of mammalian cells. Its molecular structure is compose by N-acyl-Derythro-sphingosylphosphorylcholine. The function of the SM related to membrane signaling and protein trafficking are relied on the interactions of the SM, cations, cholesterol and proteins. In this report, the interaction of three different nature SMs, cations and cholesterol at air/aqueous interfaces studied by high-resolution broadband sum frequency vibrational spectroscopy, respectively. Our results shed lights on understanding the relationship between SMs monolayer, cholesterol and Cations.

  20. Process Parameters on the Crystallization and Morphology of Hydroxyapatite Powders Prepared by a Hydrolysis Method

    Science.gov (United States)

    Wang, Moo-Chin; Hon, Min-Hsiung; Chen, Hui-Ting; Yen, Feng-Lin; Hung, I.-Ming; Ko, Horng-Huey; Shih, Wei-Jen

    2013-07-01

    The effects of process parameters on the crystallization and morphology of hydroxyapatite (Ca10(PO4)6(OH)2, HA) powders synthesized from dicalcium phosphate dihydrate (CaHPO4·2H2O, DCPD) using a hydrolysis method have been investigated. X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) were used to characterize the synthesized powders. When DCPD underwent hydrolysis in 2.5 NaOH solution (Na(aq)) at 303 K to 348 K (30 °C to 75 °C) for 1 hour, the XRD results revealed that HA was obtained for all the as-dried samples. The SEM morphology of the HA powders for DCPD hydrolysis produced at 348 K (75 °C) shows regular alignment and a short rod shape with a size of 200 nm in length and 50 nm in width. With DCPD hydrolysis in 2.5 M NaOH(aq) holding at 348 K (75 °C) for 1 to 24 hours, XRD results demonstrated that all samples were HA and no other phases could be detected. Moreover, the XRD results also show that all the as-dried powders still maintained the HA structure when DCPD underwent hydrolysis in 0.1 to 5 M NaOH(aq) at 348 K (75 °C) for 1 hour. Otherwise, the full transformation from HA to octa-calcium phosphate (OCP, Ca8H2(PO4)6·5H2O) occurred when hydrolysis happened in 10 M NaOH(aq). FT-IR spectra analysis revealed that some carbonated HA (Ca10(PO4)6(CO3), CHA) had formed. The SEM morphology results show that the 60 to 65 nm width of the uniformly long rods with regular alignment formed in the HA powder aggregates when DCPD underwent hydrolysis in 2.5 M NaOH(aq) at 348 K (75 °C) for 1 hour.

  1. CuO-Nanoparticles Catalyzed Synthesis of 1,4-Disubstituted-1,2,3 ...

    Indian Academy of Sciences (India)

    John Paul Raj

    2018-04-13

    Apr 13, 2018 ... has been developed for the synthesis of 1,2,3-triazoles. A library of 1 ... Kuang et al., described Cu-catalyzed synthesis of 1H-. 1,2,3-triazoles from 1 ..... Tornøe C W, Christensen C and Meldal M 2002 Peptido- triazoles on solid ... 2015 Copper-catalyzed [3+2] cycloaddition/oxidation reactions between ...

  2. Progressing batch hydrolysis process

    Science.gov (United States)

    Wright, J.D.

    1985-01-10

    A progressive batch hydrolysis process is disclosed for producing sugar from a lignocellulosic feedstock. It comprises passing a stream of dilute acid serially through a plurality of percolation hydrolysis reactors charged with feed stock, at a flow rate, temperature and pressure sufficient to substantially convert all the cellulose component of the feed stock to glucose. The cooled dilute acid stream containing glucose, after exiting the last percolation hydrolysis reactor, serially fed through a plurality of pre-hydrolysis percolation reactors, charged with said feedstock, at a flow rate, temperature and pressure sufficient to substantially convert all the hemicellulose component of said feedstock to glucose. The dilute acid stream containing glucose is cooled after it exits the last prehydrolysis reactor.

  3. Zeolite 5A Catalyzed Etherification of Diphenylmethanol

    Science.gov (United States)

    Cooke, Jason; Henderson, Eric J.; Lightbody, Owen C.

    2009-01-01

    An experiment for the synthetic undergraduate laboratory is described in which zeolite 5A catalyzes the room temperature dehydration of diphenylmethanol, (C[subscript 6]H[subscript 5])[subscript 2]CHOH, producing 1,1,1',1'-tetraphenyldimethyl ether, (C[subscript 6]H[subscript 5])[subscript 2]CHOCH(C[subscript 6]H[subscript 5])[subscript 2]. The…

  4. Catalytic hydrolysis of ammonia borane: Intrinsic parameter estimation and validation

    Energy Technology Data Exchange (ETDEWEB)

    Basu, S.; Gore, J.P. [School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907-2088 (United States); School of Chemical Engineering, Purdue University, West Lafayette, IN 47907-2100 (United States); Energy Center in Discovery Park, Purdue University, West Lafayette, IN 47907-2022 (United States); Zheng, Y. [School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907-2088 (United States); Energy Center in Discovery Park, Purdue University, West Lafayette, IN 47907-2022 (United States); Varma, A.; Delgass, W.N. [School of Chemical Engineering, Purdue University, West Lafayette, IN 47907-2100 (United States); Energy Center in Discovery Park, Purdue University, West Lafayette, IN 47907-2022 (United States)

    2010-04-02

    Ammonia borane (AB) hydrolysis is a potential process for on-board hydrogen generation. This paper presents isothermal hydrogen release rate measurements of dilute AB (1 wt%) hydrolysis in the presence of carbon supported ruthenium catalyst (Ru/C). The ranges of investigated catalyst particle sizes and temperature were 20-181 {mu}m and 26-56 C, respectively. The obtained rate data included both kinetic and diffusion-controlled regimes, where the latter was evaluated using the catalyst effectiveness approach. A Langmuir-Hinshelwood kinetic model was adopted to interpret the data, with intrinsic kinetic and diffusion parameters determined by a nonlinear fitting algorithm. The AB hydrolysis was found to have an activation energy 60.4 kJ mol{sup -1}, pre-exponential factor 1.36 x 10{sup 10} mol (kg-cat){sup -1} s{sup -1}, adsorption energy -32.5 kJ mol{sup -1}, and effective mass diffusion coefficient 2 x 10{sup -10} m{sup 2} s{sup -1}. These parameters, obtained under dilute AB conditions, were validated by comparing measurements with simulations of AB consumption rates during the hydrolysis of concentrated AB solutions (5-20 wt%), and also with the axial temperature distribution in a 0.5 kW continuous-flow packed-bed reactor. (author)

  5. Enantioselective Intramolecular CH-Insertions upon Cu-Catalyzed Decomposition of Phenyliodonium Ylides

    Directory of Open Access Journals (Sweden)

    Christelle Boléa

    2001-02-01

    Full Text Available The Cu-catalyzed intramolecular CH insertion of phenyliodonium ylide 5b has been investigated at 0° C in the presence of several chiral ligands. Enantioselectivities vary in the range of 38–72 %, and are higher than those resulting from reaction of the diazo compound 5c at 65° C. The results are consistent with a carbenoid mechanism for Cu-catalyzed decomposition of phenyliodonium ylides.

  6. Reactions of saccharides catalyzed by molybdate ions. XXXIII. Use of. cap alpha. (U-/sup 14/C)glucan for preparation of /sup 14/C-labelled saccharides

    Energy Technology Data Exchange (ETDEWEB)

    Bilik, V; Biely, P [Institute of Chemistry, Centre for Chemical Research, Slovak Academy of Sciences, Bratislava (Czechoslovakia); Kolina, J [Ustav pro Vyzkum, Vyrobu a Vyuziti Radioisotopu, Prague (Czechoslovakia)

    1984-01-01

    D-(U-/sup 14/C)glucose obtained in acid hydrolysis of ..cap alpha..-(U-/sup 14/C)glucan (2 M-HCl) was epimerized under a catalytic action of molybdate ions to D-(U-/sup 14/C)mannose isolated with a 20% yield. Oxidative degradation of 4-nitrophenylhydrazones of D-(U-/sup 14/C)arabinose and D-(U-/sup 14/C)xylose resulted in D-(U-/sup 14/C)erythrose and D-(U-/sup 14/C)threose, respectively, with a 15% yield relative to the starting aldopentoses. Nitromethane synthesis with D-(U-/sup 14/C)lyxose followed by oxidative decomposition of the corresponding nitrohexitols yielded /sup 14/C-labelled D-galactose. Described is also the preparation of D-(U-/sup 14/C)arabinose from D-(U-/sup 14/C)glucose and the conversion of D-(U-/sup 14/C)arabinose to D-(U-/sup 14/C)xylose and D-(U-/sup 14/C)lyxose.

  7. Kinetic study of the thermal hydrolysis of Agave salmiana for mezcal production.

    Science.gov (United States)

    Garcia-Soto, M J; Jimenez-Islas, H; Navarrete-Bolanos, J L; Rico-Martinez, R; Miranda-Lopez, R; Botello-Alvarez, J E

    2011-07-13

    The kinetics of the thermal hydrolysis of the fructans of Agave salmiana were determined during the cooking step of mezcal production in a pilot autoclave. Thermal hydrolysis was achieved at different temperatures and cooking times, ranging from 96 to 116 °C and from 20 to 80 h. A simple kinetic model of the depolymerization of fructans to monomers and other reducing sugars and of the degradation of reducing sugars to furans [principally 5-(hydroxymethyl)furfural, HMF] was developed. From this model, the rate constants of the reactions were calculated, as well as the pre-exponential factors and activation energies of the Arrhenius equation. The model was found to fit the experimental data well. The tradeoff between a maximum fructan hydrolysis and a critical furan concentration in allowing for the best ethanol yield during fermentation was investigated. The results indicated that the thermal hydrolysis of agave was optimal, from the point of view of ethanol yield in the ensuing fermentation, in the temperature range of 106-116 °C and the cooking range time of 6-14 h. The optimal conditions corresponded to a fructan hydrolysis of 80%, producing syrups with furan and reducing sugar concentrations of 1 ± 0.1 and 110 ± 10 g/L, respectively.

  8. Rh(III) -Catalyzed C-H Olefination of Benzoic Acids under Mild Conditions using Oxygen as the Sole Oxidant.

    Science.gov (United States)

    Jiang, Quandi; Zhu, Changlei; Zhao, Huaiqing; Su, Weiping

    2016-02-04

    Phthalide skeletons have been synthesized for the first time through a Rh(III) -catalyzed C-H olefination of benzoic acids under mild conditions using oxygen as the sole oxidant. Aromatic acids bearing a variety of functional groups could react with diverse alkenes to afford the desired cyclized lactones or uncyclized alkenylarenes in moderate-to-excellent yields. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Optimization of olive oil hydrolysis process using immobilized Lipase from Burkholderia cepacia sp. in Polyurethane

    Directory of Open Access Journals (Sweden)

    Nádia Ligianara Dewes Nyari

    2017-09-01

    Full Text Available The aim of this study was to achieve the best conditions for the  olive oil hydrolysis process at optimal pH and temperature using Burkholderia cepacia lipase immobilized in situ in rigid polyurethane support. The influences of the temperature (13.85 to 56.5ºC and pH (4.18 to 9.82 were evaluated by a central composite rotational experimental design 22. The operational stability and storage conditions were also studied. The olive oil hydrolysis process was optimized in pH 7.0, at 40°C and 15 min of reaction, with 66 and 93 U g-1 of hydrolysis activity in free and immobilized lipase, respectively, with > 700% yield. The immobilized remained stable for up to 40 days of storage at temperatures of 60oC, and for 100 days from 4 to 25°C. The operational stability of the immobilized was 6 continuous cycles. In this way, immobilization showed to be a promising alternative for its application in olive oil hydrolysis, having storage stability and reuse capability.

  10. Vanadium(IV)-stimulated hydrolysis of 2,3-diphosphoglycerate.

    Science.gov (United States)

    Stankiewicz, P J

    1989-05-01

    Vanadium(IV) stimulates the hydrolysis of 2,3-diphosphoglycerate at 23 degrees C. The pH optimum is 5.0. Reactions were analyzed by enzymatic and phosphate release assays. The products of 2,3-diphosphoglycerate hydrolysis are inorganic phosphate and 3-phosphoglycerate. The reaction is inhibited by high concentrations of 2,3-diphosphoglycerate and an equation has been formulated that describes the kinetic constants for this reaction at pH 7. The possible relevance of the reaction to the therapeutic lowering by vanadium(IV) of red cell 2,3-diphosphoglycerate in sickle-cell disease is discussed.

  11. Direct Vinylation of Alcohols or Aldehydes Employing Alkynes as Vinyl Donors: A Ruthenium Catalyzed C-C Bond Forming Transfer Hydrogenation

    Science.gov (United States)

    Patman, Ryan L.; Chaulagain, Mani Raj; Williams, Vanessa M.; Krische, Michael J.

    2011-01-01

    Under the conditions of ruthenium catalyzed transfer hydrogenation, 2-butyne couples to benzylic and aliphatic alcohols 1a–1i to furnish allylic alcohols 2a–2i, constituting a direct C-H vinylation of alcohols employing alkynes as vinyl donors. Under related transfer hydrogenation conditions employing formic acid as terminal reductant, 2-butyne couples to aldehydes 4a, 4b, and 4e to furnish identical products of carbonyl vinylation 2a, 2b, and 2e. Thus, carbonyl vinylation is achieved from the alcohol or the aldehyde oxidation level in the absence of any stoichiometric metallic reagents. Nonsymmetric alkynes 6a–6c couple efficiently to aldehyde 4b to provide allylic alcohols 2m–2o as single regioisomers. Acetylenic aldehyde 7a engages in efficient intramolecular coupling to deliver cyclic allylic alcohol 8a. PMID:19173651

  12. Palladium-Catalyzed Cross-Coupling Reactions of Perfluoro Organic Compounds

    Directory of Open Access Journals (Sweden)

    Masato Ohashi

    2014-09-01

    Full Text Available In this review, we summarize our recent development of palladium(0-catalyzed cross-coupling reactions of perfluoro organic compounds with organometallic reagents. The oxidative addition of a C–F bond of tetrafluoroethylene (TFE to palladium(0 was promoted by the addition of lithium iodide, affording a trifluorovinyl palladium(II iodide. Based on this finding, the first palladium-catalyzed cross-coupling reaction of TFE with diarylzinc was developed in the presence of lithium iodide, affording α,β,β-trifluorostyrene derivatives in excellent yield. This coupling reaction was expanded to the novel Pd(0/PR3-catalyzed cross-coupling reaction of TFE with arylboronates. In this reaction, the trifluorovinyl palladium(II fluoride was a key reaction intermediate that required neither an extraneous base to enhance the reactivity of organoboronates nor a Lewis acid additive to promote the oxidative addition of a C–F bond. In addition, our strategy utilizing the synergetic effect of Pd(0 and lithium iodide could be applied to the C–F bond cleavage of unreactive hexafluorobenzene (C6F6, leading to the first Pd(0-catalyzed cross-coupling reaction of C6F6 with diarylzinc compounds.

  13. Urchin-like TiO₂@C core-shell microspheres: coupled synthesis and lithium-ion battery applications.

    Science.gov (United States)

    Liu, Zhenyu; Liu, Jing; Liu, Junfeng; Wang, Li; Zhang, Guoxin; Sun, Xiaoming

    2014-05-21

    Carbon coated urchin-like TiO2 microspheres were prepared through coupled hydrolysis of titanium tetrachloride and catalyzed carbonization of glucose. Carbon coating endowed the composite with unusual structural stability at high temperature and reasonable Li-ion battery performance.

  14. Hydrolysis of aspartic acid phosphoramidate nucleotides: a comparative quantum chemical study.

    Science.gov (United States)

    Michielssens, Servaas; Tien Trung, Nguyen; Froeyen, Matheus; Herdewijn, Piet; Tho Nguyen, Minh; Ceulemans, Arnout

    2009-09-07

    L-Aspartic acid has recently been found to be a good leaving group during HIV reverse transcriptase catalyzed incorporation of deoxyadenosine monophosphate (dAMP) in DNA. This showed that L-Asp is a good mimic for the pyrophosphate moiety of deoxyadenosine triphosphate. The present work explores the thermochemistry and mechanism for hydrolysis of several models for L-aspartic-dAMP using B3LYP/DGDZVP, MP2/6-311++G** and G3MP2 level of theory. The effect of the new compound is gradually investigated: starting from a simple methyl amine leaving group up to the aspartic acid leaving group. The enzymatic environment was mimicked by involving two Mg(2+) ions and some important active site residues in the reaction. All reactions are compared to the corresponding O-coupled leaving group, which is methanol for methyl amine and malic acid for aspartic acid. With methyl amine as a leaving group a tautomeric associative or tautomeric dissociative mechanism is preferred and the barrier is lower than the comparable mechanism with methanol as a leaving group. The calculations on the aspartic acid in the enzymatic environment show that qualitatively the mechanism is the same as for triphosphate but the barrier for hydrolysis by the associative mechanism is higher for L-aspartic-dAMP than for L-malic-dAMP and pyrophosphate.

  15. Cellulose nanofiber isolation from palm oil Empty Fruit Bunches (EFB) through strong acid hydrolysis

    Science.gov (United States)

    Setyaningsih, Dwi; Uju; Muna, Neli; Isroi; Budi Suryawan, Nyoman; Azid Nurfauzi, Ami

    2018-03-01

    The palm oil industry produces about 25-26% of palm oil empty fruit bunches. The empty fruit bunch of palm oil contains cellulose up to 36.67%. This is a good opportunity for the synthesis of cellulose nanofiber (CNF). Cellulose nanofiber is a nano-sized cellulose material that has unique physical and mechanical properties. The synthesis was performed using a strong acid method with sulfuric acid. Sulfuric acid removes the amorphous region of cellulose so that the crystalline part can be isolated. CNF yield measurement showed that temperature, time, acid concentration, and interaction between each factor were affecting significantly to CNF yield. The result showed that yield of 14.98 grams, was obtained by hydrolysis at 35°C for 6 hours and 55% acid concentration. The crystallinity measurement showed that the temperature, time, acid concentration, and interaction between each factor during hydrolysis were not affected significantly to percent value of CNF crystallinity. The result showed that 31.1% of crystallinity, was obtained by hydrolysis at 45°C for 3 hours and 55% of acid concentration. The size measurement showed that the temperature, time, acid concentration and interaction between each factor were affected significantly. The result showed 894.25 nm as the best result, obtained by hydrolysis with 35°C and 60% acid concentration for 6 hours. CNF color was white with the best dispersion of hydrolysis at 35°C of 55% for 6 hours.

  16. Lecithin-cholesterol acyltransferase (LCAT) catalyzes transacylation of intact cholesteryl esters. Evidence for the partial reversal of the forward LCAT reaction

    International Nuclear Information System (INIS)

    Sorci-Thomas, M.; Babiak, J.; Rudel, L.L.

    1990-01-01

    Lecithin-cholesterol acyltransferase (LCAT) catalyzes the intravascular synthesis of lipoprotein cholesteryl esters by converting cholesterol and lecithin to cholesteryl ester and lysolecithin. LCAT is unique in that it catalyzes sequential reactions within a single polypeptide sequence. In this report we find that LCAT mediates a partial reverse reaction, the transacylation of lipoprotein cholesteryl oleate, in whole plasma and in a purified, reconstituted system. As a result of the reverse transacylation reaction, a linear accumulation of [3H]cholesterol occurred during incubations of plasma containing high density lipoprotein labeled with [3H]cholesteryl oleate. When high density lipoprotein labeled with cholesteryl [14C]oleate was also included in the incubation the labeled fatty acyl moiety remained in the cholesteryl [14C]oleate pool showing that the formation of labeled cholesterol did not result from hydrolysis of the doubly labeled cholesteryl esters. The rate of release of [3H]cholesterol was only about 10% of the forward rate of esterification of cholesterol using partially purified human LCAT and was approximately 7% in whole monkey plasma. Therefore, net production of cholesterol via the reverse LCAT reaction would not occur. [3H]Cholesterol production from [3H]cholesteryl oleate was almost completely inhibited by a final concentration of 1.4 mM 5,5'-dithiobis(nitrobenzoic acid) during incubation with either purified LCAT or whole plasma. Addition of excess lysolecithin to the incubation system did not result in the formation of [14C]oleate-labeled lecithin, showing that the reverse reaction found here for LCAT was limited to the last step of the reaction. To explain these results we hypothesize that LCAT forms a [14C]oleate enzyme thioester intermediate after its attack on the cholesteryl oleate molecule

  17. Alkali free hydrolysis of sodium borohydride for hydrogen generation under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, M.J.F.; Pinto, A.M.F.R. [Centro de Estudos de Fenomenos de Transporte, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias s/n, 4200-465 Porto (Portugal); Gales, L. [Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto and Instituto de Ciencias Biomedicas Abel Salazar, Largo Prof. Abel Salazar 2, 4099-003 Porto (Portugal); Fernandes, V.R.; Rangel, C.M. [Laboratorio Nacional de Energia e Geologia - LNEG, Fuel Cells and Hydrogen Unit Estrada do Paco do Lumiar 22, 1649-038 Lisboa (Portugal)

    2010-09-15

    The present study is related with the production of hydrogen gas (H{sub 2}), at elevated pressures and with high gravimetric storage density, to supply a PEM fuel cell on-demand. To achieve this goal, solid sodium borohydride (NaBH{sub 4}) was mixed with a proper amount of a powder reused nickel-ruthenium based catalyst (Ni-Ru based/NaBH{sub 4}: 0.2 and 0.4 g/g; {approx}150 times reused) inside the bottom of a batch reactor. Then, a stoichiometric amount of pure liquid water (H{sub 2}O/NaBH{sub 4}: 2-8 mol/mol) was added and the catalyzed NaBH{sub 4} hydrolysis evolved, in the absence of an alkali inhibitor. In this way, this research work is designated alkali free hydrolysis of NaBH{sub 4} for H{sub 2} generation. This type of hydrolysis is excellent from an environmental point of view because it does not involve strongly caustic solutions. Experiments were performed in three batch reactors with internal volumes 646, 369 and 229 cm{sup 3}, and having different bottom geometries (flat and conical shapes). The H{sub 2} generated was a function of the added water and completion was achieved with H{sub 2}O/NaBH{sub 4} = 8 mol/mol. The results show that hydrogen yields and rates increase remarkably increasing both system temperature and pressure. Reactor bottom shape influences deeply H{sub 2} generation: the conical bottom shape greatly enhances the rate and practically eliminates the reaction induction time. Our system of compressed hydrogen generation up to 1.26 MPa shows 6.3 wt% and 70 kg m{sup -3}, respectively, for gravimetric and volumetric hydrogen storage capacities (materials-only basis) and therefore is a viable hydrogen storage candidate for portable applications. (author)

  18. Rhodium(III)-Catalyzed Activation of C(sp3)-H Bonds and Subsequent Intermolecular Amidation at Room Temperature.

    Science.gov (United States)

    Huang, Xiaolei; Wang, Yan; Lan, Jingbo; You, Jingsong

    2015-08-03

    Disclosed herein is a Rh(III)-catalyzed chelation-assisted activation of unreactive C(sp3)-H bonds, thus enabling an intermolecular amidation to provide a practical and step-economic route to 2-(pyridin-2-yl)ethanamine derivatives. Substrates with other N-donor groups are also compatible with the amidation. This protocol proceeds at room temperature, has a relatively broad functional-group tolerance and high selectivity, and demonstrates the potential of rhodium(III) in the promotive functionalization of unreactive C(sp3)-H bonds. A rhodacycle having a SbF6(-) counterion was identified as a plausible intermediate. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Rhenium and Manganese-Catalyzed Selective Alkenylation of Indoles

    KAUST Repository

    Wang, Chengming

    2018-04-06

    An efficient rhenium‐catalyzed regioselective C‐H bond alkenylation of indoles is reported. The protocol operates well for internal as well as terminal alkynes, affording products in good to excellent yields. Furthermore, a manganese catalyzed, acid free, regioselective C2‐alkenylation of indoles with internal alkynes is described. The directing groups can be easily removed after the reaction and the resulting products can be used as valuable building blocks for the synthesis of diverse heterocyclic compounds.

  20. Rhenium and Manganese-Catalyzed Selective Alkenylation of Indoles

    KAUST Repository

    Wang, Chengming; Rueping, Magnus

    2018-01-01

    An efficient rhenium‐catalyzed regioselective C‐H bond alkenylation of indoles is reported. The protocol operates well for internal as well as terminal alkynes, affording products in good to excellent yields. Furthermore, a manganese catalyzed, acid free, regioselective C2‐alkenylation of indoles with internal alkynes is described. The directing groups can be easily removed after the reaction and the resulting products can be used as valuable building blocks for the synthesis of diverse heterocyclic compounds.

  1. Rhodium catalyzed regioselective arene homologation of aryl urea via double C-H bond activation and migratory insertion of alkyne

    Institute of Scientific and Technical Information of China (English)

    Yan Wang; Hao Zhou; Ke Xu; Mei-Hua Shen; Hua-Dong Xu

    2017-01-01

    A convenient rhodium catalyzed oxidative arene homologation of aniline derivatives with symmetrical or unsymmetrical alkynes using Cu(OAc)2 as oxidant is described.Urea group is shown to be effective as a directing group for initial ortho C-H activation.Two migratory insertion events of alkyne into Rh-C bond occur successively,both with complete regioselectivity.This method is particularly useful for synthesis of polyarenes with different substituents,which has not been reported with conventional protocol.A mechanism has been proposed to explain the observed data.

  2. Analysis of myo-inositol hexakisphosphate hydrolysis by Bacillus phytase

    DEFF Research Database (Denmark)

    Kerovuo, J.; Rouvinen, J.; Hatzack, Frank-Andreas

    2000-01-01

    Phytic acid (myo-inositol hexakisphosphate, InsP(6)) hydrolysis by Bacillus phytase (PhyC) was studied. The enzyme hydrolyses only three phosphates from phytic acid. Moreover, the enzyme seems to prefer the hydrolysis of every second phosphate over that of adjacent ones. Furthermore, it is very...... a reaction mechanism different from that of other phytases. By combining the data presented in this study with (1) structural information obtained from the crystal structure of Bacillus amyloliquefaciens phytase [Ha, Oh, Shin, Kim, Oh, Kim, Choi and Oh (2000) Nat. Struct. Biol. 7, 147-153], and (2) computer...

  3. Alpha-Helical Fragaceatoxin C Nanopore Engineered for Double-Stranded and Single-Stranded Nucleic Acid Analysis

    NARCIS (Netherlands)

    Wloka, Carsten; Mutter, Natalie Lisa; Soskine, Misha; Maglia, Giovanni

    2016-01-01

    Nanopores are used in single-molecule DNA analysis and sequencing. Herein, we show that Fragaceatoxin C (FraC), an α-helical pore-forming toxin from an actinoporin protein family, can be reconstituted in sphingomyelin-free standard planar lipid bilayers. We engineered FraC for DNA analysis and show

  4. Verification of the interstitial carbide hydrolysis mechanism by a radioanalytical method

    International Nuclear Information System (INIS)

    Brozek, V.; Hajek, B.; Karen, P.

    1983-01-01

    The hydrolytic products of manganese carbide Mn 7 C 3 are hydrogen and a number of paraffins of the series CH 4 , C 2 H 6 , C 3 H 8 , etc., whose concentrations characteristically decrease with increasing number of carbon atoms in the hydrocarbon molecule. A radioanalytical method applied after Mn 7 C 3 hydrolysis by tritium oxide has revealed that an analogous series of olefins in trace concentrations is formed well as well. It has been confirmed that the sum of the concentrations of hydrocarbons higher than C 4 corresponds to the trend of the series. A stoichiometric and structurally consistent radical mechanism of Mn 7 C 3 hydrolysis is proposed as derived from the composition of the hydrolytic products. The initial components of the radical reactions could be CH 2 , CH 3 and H radicals. The statistical and combinatorial aspects of the mechanism are also discussed. (author)

  5. The synthesis of [[sup 2]H],[[sup 3]H], and [[sup 14]C]-labeled 8[beta]-[(methylthio)methyl]-6-propylergoline mesylate (pergolide mesylate), a potent, long-acting dopamine agonist

    Energy Technology Data Exchange (ETDEWEB)

    Wheeler, W.J.; Kau, D.L.K.; Bach, N.J. (Lilly (Eli) and Co., Indianapolis, IN (United States). Lilly Research Labs.)

    1990-03-01

    The [[sup 3]H]- and two[[sup 14]C]-isopomers of 8[beta]-[(methylthio)methyl]-6-propylergoline mesylate (pergolide mesylate) have been synthesized. The [[sup 3]H]-derivative was synthesized by the palladium catalyzed tritiation of the corresponding 6-allyl derivative. Reaction of 8[beta]-[(methylthio)methyl]-ergoline with 1-[[sup 14]C]-1-propyl bromide yielded pergolide labeled in the 6-propyl group. Alternatively, reaction of 8[beta]-mesyloxy-6-propylergoline with [[sup 14]C]-sodium cyanide, followed by base hydrolysis, yielded 8 [beta]-carboxy-6-propylergoline-[[sup 14]C], which was subsequently converted to pergolide mesylate radiolabeled in the 17-position via a four step sequence. (Author).

  6. Hydrolysis of fish protein by Bacillus megaterium cells immobilized in radiation induced polymerized wood

    International Nuclear Information System (INIS)

    Ghosh, S.; Alur, M.D.; Nerkar, D.P.

    1992-01-01

    The immobilization of Bacillus megaterium cells in radiation-induced polymerized wood was studied for hydrolysis of trash fish protein. The optimum conditions and reaction kinetics for hydrolysis of protein by free and immobilized cells were found to be similar. Maximum hydrolysis occurred at 50 o C and at pH 7.5 with 15-20% (w/v) of immobilized matrix. The soluble content of the resultant hydrolysate about 2.4% (w/v). (author). 10 refs., 4 figs

  7. Effect of γ-irradiation on the acidic hydrolysis of free-hemicellulose thistle

    International Nuclear Information System (INIS)

    Suarez, C.; Paz Saa, D.; Diaz Palma, A.

    1983-01-01

    The effect of gamma-irradiation on the subsequent acidic hydrolysis of free-hemicellulose ''Onopordum Nervosum Boiss'' thistle is determined. It is shown the influence of gamma-irradiation on the yield or sugar obtained from the batchwise hydrolysis of the cellulose (1% H 2 SO 4 and 180 0 C) at increasing doses. At all irradiation levels studied, the rate of hydrolysis of thistle samples was higher than the rate of hydrolysis of the cellulose from paper treated similarly. The maximum overall yield of sugar in the irradiated lignocellulosic material was about 66 0 at 100 MRad, less than two times the yield obtainable from the control. The corresponding yield from paper was 53%, 2'3 times that of the control. Irradiation under 1% H 2 SO 4 does not enhance the yield anyway. (author)

  8. Lactose hydrolysis in an enzymatic membrane reactor

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, B; Huyghebaert, A

    1987-10-01

    The enzymatic hydrolysis of lactose in whey permeate with subsequent recuperation of Saccharomyces lactis lactase by means of ultrafiltration was investigated. In whey permeate, S. lactis lactase shows maximal activity at pH 6.5; the optimal temperature was found to be 45/sup 0/C and is limited by strong thermal inactivation beyond this temperature. High activity combined with acceptable thermal inactivation (< 10% after 5 h incubation) was established at 30/sup 0/C. S. lactis lactase also displays considerable activity at low temperature (5/sup 0/C). Enzyme stability is reduced drastically by demineralisation: addition of low concentrations of manganese ions (10/sup -3/ M) considerably enhances stability. Using a DDS Lab-Unit 35 fitted with GR61PP polysulphon membranes (cut-off: 20.000), pilot scale experiments were carried out (pH 6.5; 30/sup 0/C) in which whey permeate was hydrolyzed to a degree of hydrolysis of 82% minimum. Enzyme recuperation amounted to 96.5% per batch, all enzyme activity loss being due to thermal inactivation. Microbiological examination of the enzymatic membrane reactor showed that growth of mcicroorganisms can largely be suppressed by working at lower temperature (5/sup 0/C). Eventually, 50 ppm H/sub 2/O/sub 2/ or sterile filtration will adequately solve microbiological problems without affecting enzyme activity.

  9. Fullerene-catalyzed reduction of azo derivatives in water under UV irradiation

    KAUST Repository

    Guo, Yong; Li, Wengang; Yan, Jingjing; Moosa, Basem; Amad, Maan H.; Werth, Charles; Khashab, Niveen M.

    2012-01-01

    Metal-free fullerene (C60) was found to be an effective catalyst for the reduction of azo groups in basic aqueous solution under UV irradiation in the presence of NaBH4. Use of NaBH4 by itself is not sufficient to reduce the azo dyes without the assistance of a metal catalyst such as Pd and Ag. Experimental and theoretical results suggest that C 60 catalyzes this reaction by using its vacant orbital to accept the electron in the bonding orbital of azo dyes, which leads to the activation of the N=N bond. UV irradiation increases the ability of C60 to interact with electron-donor moieties in azo dyes. Filling a vacancy: Experimental and theoretical methods have been combined to show that C60-catalyzed reductions of azo compounds form aromatic amines under UV irradiation (see scheme). The obtained results show that C60 acts as an electron acceptor to catalyze the reduction of azo compounds, and the role of UV irradiation is to increase the ability of C60 to interact with electron-donor moieties in azo compounds. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Fullerene-catalyzed reduction of azo derivatives in water under UV irradiation

    KAUST Repository

    Guo, Yong

    2012-09-27

    Metal-free fullerene (C60) was found to be an effective catalyst for the reduction of azo groups in basic aqueous solution under UV irradiation in the presence of NaBH4. Use of NaBH4 by itself is not sufficient to reduce the azo dyes without the assistance of a metal catalyst such as Pd and Ag. Experimental and theoretical results suggest that C 60 catalyzes this reaction by using its vacant orbital to accept the electron in the bonding orbital of azo dyes, which leads to the activation of the N=N bond. UV irradiation increases the ability of C60 to interact with electron-donor moieties in azo dyes. Filling a vacancy: Experimental and theoretical methods have been combined to show that C60-catalyzed reductions of azo compounds form aromatic amines under UV irradiation (see scheme). The obtained results show that C60 acts as an electron acceptor to catalyze the reduction of azo compounds, and the role of UV irradiation is to increase the ability of C60 to interact with electron-donor moieties in azo compounds. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. DNA gyrase with a single catalytic tyrosine can catalyze DNA supercoiling by a nicking-closing mechanism

    Science.gov (United States)

    Gubaev, Airat; Weidlich, Daniela; Klostermeier, Dagmar

    2016-01-01

    The topological state of DNA is important for replication, recombination and transcription, and is regulated in vivo by DNA topoisomerases. Gyrase introduces negative supercoils into DNA at the expense of ATP hydrolysis. It is the accepted view that gyrase achieves supercoiling by a strand passage mechanism, in which double-stranded DNA is cleaved, and a second double-stranded segment is passed through the gap, converting a positive DNA node into a negative node. We show here that gyrase with only one catalytic tyrosine that cleaves a single strand of its DNA substrate can catalyze DNA supercoiling without strand passage. We propose an alternative mechanism for DNA supercoiling via nicking and closing of DNA that involves trapping, segregation and relaxation of two positive supercoils. In contrast to DNA supercoiling, ATP-dependent relaxation and decatenation of DNA by gyrase lacking the C-terminal domains require both tyrosines and strand passage. Our results point towards mechanistic plasticity of gyrase and might pave the way for finding novel and specific mechanism-based gyrase inhibitors. PMID:27557712

  12. Kinetic study of microwave-assisted alkaline hydrolysis of Jatropha curcas oil

    Science.gov (United States)

    Yusuf, Nur'aini Raman; Kamil, Ruzaimah Nik Mohamad; Yusup, Suzana

    2016-11-01

    The kinetics of hydrolysis of Jatropha curcas oil under microwave irradation in the presence of alkaline solution was studied. The temperature of 50°C, 65°C and 80°C were studied in the range of optimum condition of 1.75 M catalyst, solvent/oil ratio of (1: 68) and 15 minutes reaction time. The rate constants of oil hydrolysis are corresponding to triglyceride disappearance concentration. The rates of reaction for fatty acids production was determined by pseudo first order. The activation energy (Ea) achieved at 30.61 kJ/mol is lower using conventional method. This conclude that the rate of reaction via microwave heating is less temperature sensitive therefore reaction can be obtained at lower temperature.

  13. Enzymatic hydrolysis of Amaranth flour - differential scanning calorimetry and scanning electron microscopy studies

    Energy Technology Data Exchange (ETDEWEB)

    Barba de la Rosa, A.P.; Paredes-Lopez, O.; Carabez-Trejo, A.; Ordorica-Falomir, C. (Instituto Politecnico Nacional, Irapuato (Mexico). Centro de Investigacion y de Estudios Avanzados)

    1989-11-01

    High-protein amaranth flour (HPAF) and carbohydrate rich fraction (CRF) were produced from raw flour in a single-step process using a heat-stable alpha-amylase preparation. Protein content of flour increased from 15 to about 30 or 39% at liquefaction temperatures of 70 or 90{sup 0}C, respectively and 30 min hydrolysis time. CRF exhibited 14-22 DE. Enzymatic action at 70{sup 0}C increased endotherm temperature and gelatinization enthalpy of HPAF, in relation to gelatinized flour, as assessed by differential scanning calorimetry (DSC). Hydrolysis at 90{sup 0}C did not affect significantly (P > 0.05) DSC peak temperature. It is suggested that these changes in DSC performance might result from differences in amount and type of low-molecular weight carbohydrates and residual starch. Scanning electron microscopy (SEM) demonstrated that hydrolysis temperature changed substantially the structural appearance of flour particles. HPAF and CRF might find applications as dry milk extender and sweetener, respectively. (orig.).

  14. Carbon-based strong solid acid for cornstarch hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Nata, Iryanti Fatyasari, E-mail: yanti_tkunlam@yahoo.com [Chemical Engineering Study Program, Faculty of Engineering, Lambung Mangkurat University, Jl. A. Yani Km. 36 Banjarbaru, South Kalimantan 70714 (Indonesia); Irawan, Chairul; Mardina, Primata [Chemical Engineering Study Program, Faculty of Engineering, Lambung Mangkurat University, Jl. A. Yani Km. 36 Banjarbaru, South Kalimantan 70714 (Indonesia); Lee, Cheng-Kang, E-mail: cklee@mail.ntust.edu.tw [Department of Chemical Engineering, National Taiwan University of Science and Technology, 43 Keelung Rd. Sec.4, Taipei 106, Taiwan (China)

    2015-10-15

    Highly sulfonated carbonaceous spheres with diameter of 100–500 nm can be generated by hydrothermal carbonization of glucose in the presence of hydroxyethylsulfonic acid and acrylic acid at 180 °C for 4 h. The acidity of the prepared carbonaceous sphere C4-SO{sub 3}H can reach 2.10 mmol/g. It was used as a solid acid catalyst for the hydrolysis of cornstarch. Total reducing sugar (TRS) concentration of 19.91 mg/mL could be obtained by hydrolyzing 20 mg/mL cornstarch at 150 °C for 6 h using C4-SO{sub 3}H as solid acid catalyst. The solid acid catalyst demonstrated good stability that only 9% decrease in TRS concentration was observed after five repeat uses. The as-prepared carbon-based solid acid catalyst can be an environmentally benign replacement for homogeneous catalyst. - Highlights: • Carbon solid acid was successfully prepared by one-step hydrothermal carbonization. • The acrylic acid as monomer was effectively reduce the diameter size of particle. • The solid acid catalyst show good catalytic performance of starch hydrolysis. • The solid acid catalyst is not significantly deteriorated after repeated use.

  15. Carbon-based strong solid acid for cornstarch hydrolysis

    International Nuclear Information System (INIS)

    Nata, Iryanti Fatyasari; Irawan, Chairul; Mardina, Primata; Lee, Cheng-Kang

    2015-01-01

    Highly sulfonated carbonaceous spheres with diameter of 100–500 nm can be generated by hydrothermal carbonization of glucose in the presence of hydroxyethylsulfonic acid and acrylic acid at 180 °C for 4 h. The acidity of the prepared carbonaceous sphere C4-SO 3 H can reach 2.10 mmol/g. It was used as a solid acid catalyst for the hydrolysis of cornstarch. Total reducing sugar (TRS) concentration of 19.91 mg/mL could be obtained by hydrolyzing 20 mg/mL cornstarch at 150 °C for 6 h using C4-SO 3 H as solid acid catalyst. The solid acid catalyst demonstrated good stability that only 9% decrease in TRS concentration was observed after five repeat uses. The as-prepared carbon-based solid acid catalyst can be an environmentally benign replacement for homogeneous catalyst. - Highlights: • Carbon solid acid was successfully prepared by one-step hydrothermal carbonization. • The acrylic acid as monomer was effectively reduce the diameter size of particle. • The solid acid catalyst show good catalytic performance of starch hydrolysis. • The solid acid catalyst is not significantly deteriorated after repeated use

  16. Tunable differentiation of tertiary C-H bonds in intramolecular transition metal-catalyzed nitrene transfer reactions.

    Science.gov (United States)

    Corbin, Joshua R; Schomaker, Jennifer M

    2017-04-13

    Metal-catalyzed nitrene transfer reactions are an appealing and efficient strategy for accessing tetrasubstituted amines through the direct amination of tertiary C-H bonds. Traditional catalysts for these reactions rely on substrate control to achieve site-selectivity in the C-H amination event; thus, tunability is challenging when competing C-H bonds have similar steric or electronic features. One consequence of this fact is that the impact of catalyst identity on the selectivity in the competitive amination of tertiary C-H bonds has not been well-explored, despite the potential for progress towards predictable and catalyst-controlled C-N bond formation. In this communication, we report investigations into tunable and site-selective nitrene transfers between tertiary C(sp 3 )-H bonds using a combination of transition metal catalysts, including complexes based on Ag, Mn, Rh and Ru. Particularly striking was the ability to reverse the selectivity of nitrene transfer by a simple change in the identity of the N-donor ligand supporting the Ag(i) complex. The combination of our Ag(i) catalysts with known Rh 2 (ii) complexes expands the scope of successful catalyst-controlled intramolecular nitrene transfer and represents a promising springboard for the future development of intermolecular C-H N-group transfer methods.

  17. Enhancement of hydrolysis of Chlorella vulgaris by hydrochloric acid.

    Science.gov (United States)

    Park, Charnho; Lee, Ja Hyun; Yang, Xiaoguang; Yoo, Hah Young; Lee, Ju Hun; Lee, Soo Kweon; Kim, Seung Wook

    2016-06-01

    Chlorella vulgaris is considered as one of the potential sources of biomass for bio-based products because it consists of large amounts of carbohydrates. In this study, hydrothermal acid hydrolysis with five different acids (hydrochloric acid, nitric acid, peracetic acid, phosphoric acid, and sulfuric acid) was carried out to produce fermentable sugars (glucose, galactose). The hydrothermal acid hydrolysis by hydrochloric acid showed the highest sugar production. C. vulgaris was hydrolyzed with various concentrations of hydrochloric acid [0.5-10 % (w/w)] and microalgal biomass [20-140 g/L (w/v)] at 121 °C for 20 min. Among the concentrations examined, 2 % hydrochloric acid with 100 g/L biomass yielded the highest conversion of carbohydrates (92.5 %) into reducing sugars. The hydrolysate thus produced from C. vulgaris was fermented using the yeast Brettanomyces custersii H1-603 and obtained bioethanol yield of 0.37 g/g of algal sugars.

  18. Continuous-flow electro-assisted acid hydrolysis of granular potato starch via inductive methodology.

    Science.gov (United States)

    Li, Dandan; Yang, Na; Jin, Yamei; Guo, Lunan; Zhou, Yuyi; Xie, Zhengjun; Jin, Zhengyu; Xu, Xueming

    2017-08-15

    The induced electric field assisted hydrochloric acid (IEF-HCl) hydrolysis of potato starch was investigated in a fluidic system. The impact of various reaction parameters on the hydrolysis rate, including reactor number (1-4), salt type (KCl, MgCl 2 , FeCl 3 ), salt concentration (3-12%), temperature (40-55°C), and hydrolysis time (0-60h), were comprehensively assessed. Under optimal conditions, the maximum reducing sugar content in the hydrolysates was 10.59g/L. X-ray diffraction suggested that the crystallinity of IEF-HCl-modified starches increased with the intensification of hydrolysis but was lower than that of native starch. Scanning electron microscopy indicated that the surface and interior regions of starch granules were disrupted by the hydrolysis. The solubility of IEF-HCl-modified starches increased compared to native starch while their swelling power decreased, contributing to a decline in paste viscosity. These results suggest that IEF is a notable potential electrotechnology to conventional hydrolysis under mild conditions without any electrode touching the subject. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Synthesis of Arylthiopyrimidines by Copper-catalyzed Aerobic Oxidative C-S Cross-coupling

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ok Suk; Kim, Hyeji; Sohn, Jeong-Hun [Chungnam National University, Daejeon (Korea, Republic of); Lee, Hee-Seung [KAIST, Daejeon (Korea, Republic of); Shin, Hyunik [Yonsung Fine Chemicals R and D Center, Suwon (Korea, Republic of)

    2016-02-15

    Copper-catalyzed C–S cross-coupling reactions have been considered as powerful tools in synthetic chemistry and utilized for diverse heterocycle syntheses. In the reactions, the aspects of no need of ligands has been particular advantage over other metal catalysis. We have developed a Cu-catalyzed cascade reaction for the synthesis of fully substituted 2-arylthiopyrimidines from 3,4-dihydropyrimidine-2(1H)-thiones (DHPMs) under aerobic conditions. This cascade reaction of DHPM with aryl iodide proceeds presumably via sequential tautomerization, C–S cross-coupling, and oxidative dehydrogenation (oxidation followed by elimination). Considering that DHPM substrates were easily synthesized by Biginelli three component coupling reaction of aryl aldehyde, β-ketoester, and thiourea, the present method provides a direct access toward diverse 2-arylthiopyrimidines which have been used as a prominent substructure of drug molecules.

  20. Hydrolysis of biomass material

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Andrew J.; Orth, Rick J.; Franz, James A.; Alnajjar, Mikhail

    2004-02-17

    A method for selective hydrolysis of the hemicellulose component of a biomass material. The selective hydrolysis produces water-soluble small molecules, particularly monosaccharides. One embodiment includes solubilizing at least a portion of the hemicellulose and subsequently hydrolyzing the solubilized hemicellulose to produce at least one monosaccharide. A second embodiment includes solubilizing at least a portion of the hemicellulose and subsequently enzymatically hydrolyzing the solubilized hemicellulose to produce at least one monosaccharide. A third embodiment includes solubilizing at least a portion of the hemicellulose by heating the biomass material to greater than 110.degree. C. resulting in an aqueous portion that includes the solubilized hemicellulose and a water insoluble solids portion and subsequently separating the aqueous portion from the water insoluble solids portion. A fourth embodiment is a method for making a composition that includes cellulose, at least one protein and less than about 30 weight % hemicellulose, the method including solubilizing at least a portion of hemicellulose present in a biomass material that also includes cellulose and at least one protein and subsequently separating the solubilized hemicellulose from the cellulose and at least one protein.

  1. N-Boc amines to oxazolidinones via Pd(II)/bis-sulfoxide/Brønsted acid co-catalyzed allylic C-H oxidation.

    Science.gov (United States)

    Osberger, Thomas J; White, M Christina

    2014-08-06

    A Pd(II)/bis-sulfoxide/Brønsted acid catalyzed allylic C-H oxidation reaction for the synthesis of oxazolidinones from simple N-Boc amines is reported. A range of oxazolidinones are furnished in good yields (avg 63%) and excellent diastereoselectivities (avg 15:1) to furnish products regioisomeric from those previously obtained using allylic C-H amination reactions. Mechanistic studies suggest the role of the phosphoric acid is to furnish a Pd(II)bis-sulfoxide phosphate catalyst that promotes allylic C-H cleavage and π-allylPd functionalization with a weak, aprotic oxygen nucleophile and to assist in catalyst regeneration.

  2. Rh-Catalyzed Annulations of N-Methoxybenzamides and Ketenimines: Sterically and Electronically Controlled Synthesis of Isoquinolinones and Isoindolinones.

    Science.gov (United States)

    Zhou, Xiaorong; Zhang, Zhiyin; Zhao, Hongyang; Lu, Ping; Wang, Yanguang

    2017-04-07

    Rhodium-catalyzed C-H activation/annulation reactions of ketenimines with N-methoxybenzamides are reported. The outcome of reactions is dependent on the structure of ketenimines. The β-alkyl-substituted ketenimines furnish 3-iminoisoquinolin-1(2H)-ones in a formal [4 + 2] annulation manner, while the β-ester substituted ketenimines afford 3-aminoisoindolin-1-ones in a formal [4 + 1] annulation manner. The synthesized [4 + 2] products undergo an intramolecular Cu-catalyzed C-N coupling to be converted to benzo[4,5]imidazo[1,2-b]isoquinolin-11-ones, which can be directly prepared from ketenimines and N-methoxybenzamides by a one-pot Rh-catalyzed annulation/Cu-catalyzed C-N coupling sequence.

  3. Kinetic study of enzymatic hydrolysis of acid-pretreated coconut coir

    Science.gov (United States)

    Fatmawati, Akbarningrum; Agustriyanto, Rudy

    2015-12-01

    Biomass waste utilization for biofuel production such as bioethanol, has become more prominent currently. Coconut coir is one of lignocellulosic food wastes, which is abundant in Indonesia. Bioethanol production from such materials consists of more than one step. Pretreatment and enzymatic hydrolysis is crucial steps to produce sugar which can then be fermented into bioethanol. In this research, ground coconut coir was pretreated using dilute sulfuric acid at 121°C. This pretreatment had increased the cellulose content and decreased the lignin content of coconut coir. The pretreated coconut coir was hydrolyzed using a mix of two commercial cellulase enzymes at pH of 4.8 and temperature of 50°C. The enzymatic hydrolysis was conducted at several initial coconut coir slurry concentrations (0.1-2 g/100 mL) and reaction times (2-72 hours). The reducing sugar concentration profiles had been produced and can be used to obtain reaction rates. The highest reducing sugar concentration obtained was 1,152.567 mg/L, which was produced at initial slurry concentration of 2 g/100 mL and 72 hours reaction time. In this paper, the reducing sugar concentrations were empirically modeled as a function of reaction time using power equations. Michaelis-Menten kinetic model for enzymatic hydrolysis reaction is adopted. The kinetic parameters of that model for sulfuric acid-pretreated coconut coir enzymatic hydrolysis had been obtained which are Vm of 3.587×104 mg/L.h, and KM of 130.6 mg/L.

  4. Pretreatment and enzymatic hydrolysis of lignocellulosic biomass

    Science.gov (United States)

    Corredor, Deisy Y.

    The performance of soybean hulls and forage sorghum as feedstocks for ethanol production was studied. The main goal of this research was to increase fermentable sugars' yield through high-efficiency pretreatment technology. Soybean hulls are a potential feedstock for production of bio-ethanol due to their high carbohydrate content (≈50%) of nearly 37% cellulose. Soybean hulls could be the ideal feedstock for fuel ethanol production, because they are abundant and require no special harvesting and additional transportation costs as they are already in the plant. Dilute acid and modified steam-explosion were used as pretreatment technologies to increase fermentable sugars yields. Effects of reaction time, temperature, acid concentration and type of acid on hydrolysis of hemicellulose in soybean hulls and total sugar yields were studied. Optimum pretreatment parameters and enzymatic hydrolysis conditions for converting soybean hulls into fermentable sugars were identified. The combination of acid (H2SO4, 2% w/v) and steam (140°C, 30 min) efficiently solubilized the hemicellulose, giving a pentose yield of 96%. Sorghum is a tropical grass grown primarily in semiarid and dry parts of the world, especially in areas too dry for corn. The production of sorghum results in about 30 million tons of byproducts mainly composed of cellulose, hemicellulose, and lignin. Forage sorghum such as brown midrib (BMR) sorghum for ethanol production has generated much interest since this trait is characterized genetically by lower lignin concentrations in the plant compared with conventional types. Three varieties of forage sorghum and one variety of regular sorghum were characterized and evaluated as feedstock for fermentable sugar production. Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and X-Ray diffraction were used to determine changes in structure and chemical composition of forage sorghum before and after pretreatment and enzymatic hydrolysis

  5. Investigation of tributyl phosphate hydrolysis in polymer matrix

    International Nuclear Information System (INIS)

    Sokal'skaya, L.I.; Yakshin, V.V.; Filippov, E.A.

    1978-01-01

    Hydrolytic stability of tributyl phosphate to 2 N nitric acid solutions at a temperature of 96 +- 0.5 deg C has been investigated. Tributyl phosphate has been put into a styrene - divinylbenzene matrix. By using the method of potentiometric titration in an anhydrous medium the following has been shown: the quantity of dibutylphosphoric acid that has been formed in the process of hydrolysis of tributylphosphate put into a polymeric matrix is two times smaller than that formed in the process of hydrolysis of pure tributylphosphate under the same conditions. The solubility of tributylphosphate put into a polymer matrix of 240 mg/l in distilled water and of 150 mg/l tributylphosphate in a sodaalkaline solution has been determined

  6. Assessment of methods to determine minimal cellulase concentrations for efficient hydrolysis of cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Hogan, C.M.; Mes-Hartree, M.; Saddler, J.N. (Forintek Canada Corp., Ottawa, ON (Canada). Biotechnology and Chemistry Dept.); Kushner, D.J. (Toronto Univ., Ontario (Canada). Dept. of Microbiology)

    1990-02-01

    The enzyme loading needed to achieve substrate saturation appeared to be the most economical enzyme concentration to use for hydrolysis, based on percentage hydrolysis. Saturation was reached at 25 filter paper units per gram substrate on Solka Floc BW300, as determined by studying (a) initial adsorption of the cellulase preparation onto the substrate, (b) an actual hydrolysis or (c) a combined hydrolysis and fermentation (CHF) process. Initial adsorption of the cellulases onto the substrate can be used to determine the minimal cellulase requirements for efficient hydrolysis since enzymes initially adsorbed to the substrate have a strong role in governing the overall reaction. Trichoderma harzianum E58 produces high levels of {beta}-glucosidase and is able to cause high conversion of Solka Floc BW300 to glucose without the need for exogenous {beta}-glucosidase. End-product inhibition of the cellulase and {beta}-glucosidase can be more effectively reduced by employing a CHF process than by supplemental {beta}-glucosidase. (orig.).

  7. Prediction of fetal lung maturity using the lecithin/sphingomyelin (L/S) ratio analysis with a simplified sample preparation, using a commercial microtip-column combined with mass spectrometric analysis.

    Science.gov (United States)

    Kwak, Ho-Seok; Chung, Hee-Jung; Choi, Young Sik; Min, Won-Ki; Jung, So Young

    2015-07-01

    Fetal lung maturity is estimated using the lecithin/sphingomyelin ratio (L/S ratio) in amniotic fluid and it is commonly measured with thin-layer chromatography (TLC). The TLC method is time consuming and technically difficult; however, it is widely used because there is no alternative. We evaluated a novel method for measuring the L/S ratio, which involves a tip-column with a cation-exchange resin and mass spectrometry. Phospholipids in the amniotic fluid were extracted using methanol and chloroform. Choline-containing phospholipids such as lecithin and sphingomyelin were purified by passing them through the tip-column. LC-MS/MS and MALDI-TOF were used to directly analyze the purified samples. The L/S ratio by mass spectrometry was calculated from the sum peak intensity of the six lecithin, and that of sphingomyelin 34:1. In 20 samples, the L/S ratio determined with TLC was significantly correlated with that obtained by LC-MS/MS and MALDI-TOF. There was a 100% concordance between the L/S ratio by TLC and that by LC-MS/MS (kappa value=1.0). The concordance between the L/S ratio by TLC and that by MALDI-TOF was also 100% (kappa value=1.0). Our method provides a faster, simpler, and more reliable assessment of fetal lung maturity. The L/S ratio measured by LC-MS/MS and MALDI-TOF offers a compelling alternative method to traditional TLC. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Combined subcritical water and enzymatic hydrolysis for reducing sugar production from coconut husk

    Science.gov (United States)

    Muharja, Maktum; Junianti, Fitri; Nurtono, Tantular; Widjaja, Arief

    2017-05-01

    Coconut husk wastes are abundantly available in Indonesia. It has a potential to be used into alternative renewable energy sources such as hydrogen using enzymatic hydrolysis followed by a fermentation process. Unfortunately, enzymatic hydrolysis is hampered by the complex structure of lignocellulose, so the cellulose component is hard to degrade. In this study, Combined Subcritical Water (SCW) and enzymatic hydrolysis are applied to enhance fermentable, thereby reducing production of sugar from coconut husk. There were two steps in this study, the first step was coconut husk pretreated by SCW in batch reactor at 80 bar and 150-200°C for 60 minutes reaction time. Secondly, solid fraction from the results of SCW was hydrolyzed using the mixture of pure cellulose and xylanase enzymes. Analysis was conducted on untreated and SCW-treated by gravimetric assay, liquid fraction after SCW and solid fraction after enzymatic hydrolysis using DNS assay. The maximum yield of reducing sugar (including xylose, arabinose glucose, galactose, mannose) was 1.254 gr per 6 gr raw material, representing 53.95% of total sugar in coconut husk biomass which was obtained at 150°C 80 bar for 60 minutes reaction time of SCW-treated and 6 hour of enzymatic hydrolysis using mixture of pure cellulose and xylanase enzymes (18.6 U /gram of coconut husk).

  9. Potentiometric determination of the 'formal' hydrolysis ratio of aluminium species in aqueous solutions

    International Nuclear Information System (INIS)

    Fournier, Agathe C.; Shafran, Kirill L.; Perry, Carole C.

    2008-01-01

    The 'formal' hydrolysis ratio (h = C(OH - ) added /C(Al) total ) of hydrolysed aluminium-ions is an important parameter required for the exhaustive and quantitative speciation-fractionation of aluminium in aqueous solutions. This paper describes a potentiometric method for determination of the formal hydrolysis ratio based on an automated alkaline titration procedure. The method uses the point of precipitation of aluminium hydroxide as a reference (h = 3.0) in order to calculate the initial formal hydrolysis ratio of hydrolysed aluminium-ion solutions. Several solutions of pure hydrolytic species including aluminium monomers (AlCl 3 ), Al 13 polynuclear cluster ([Al 13 O 4 (OH) 24 (H 2 O) 12 ] 7+ ), Al 30 polynuclear cluster ([Al 30 O 8 (OH) 56 (H 2 O) 26 ] 18+ ) and a suspension of nanoparticulate aluminium hydroxide have been used as 'reference standards' to validate the proposed potentiometric method. Other important variables in the potentiometric determination of the hydrolysis ratio have also been optimised including the concentration of aluminium and the type and strength of alkali (Trizma-base, NH 3 , NaHCO 3 , Na 2 CO 3 and KOH). The results of the potentiometric analysis have been cross-verified by quantitative 27 Al solution nuclear magnetic resonance ( 27 Al NMR) measurements. The 'formal' hydrolysis ratio of a commercial basic aluminium chloride has been measured as an example of a practical application of the developed technique

  10. Computational study for the circular redox reaction of N2O with CO catalyzed by fullerometallic cations C60Fe+ and C70Fe.

    Science.gov (United States)

    Anafcheh, Maryam; Naderi, Fereshteh; Khodadadi, Zahra; Ektefa, Fatemeh; Ghafouri, Reza; Zahedi, Mansour

    2017-03-01

    We applied density functional calculations to study the circular redox reaction mechanism of N 2 O with CO catalyzed by fullerometallic cations C 60 Fe + and C 70 Fe + . The on-top sites of six-membered rings (η 6 ) of fullerene cages are the most preferred binding sites for Fe + cation, and the hexagon to pentagon migration of Fe + is unlikely under ambient thermodynamic conditions. The initial ion/molecule reaction, N 2 O rearrangement and N 2 abstraction on the considered fullerometallic cations are easier than those on the bare Fe + cation in the gas phase. Generally, our results indicate that fullerometallic ions, C 60 Fe + and C 70 Fe + , are more favorable substrates for redox reaction of N 2 O with CO in comparison to the other previously studied carbon nanostructures such as graphene and nanotubes. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. HYDROLYSIS OF AGRICULTURAL BIOMASS BY COMBINED PRETREATMENT AND ENZYMATIC METHODS IN ORDER TO PRODUCE BIOFUELS (ETHANOL, BIOGAS

    Directory of Open Access Journals (Sweden)

    STEFANA JURCOANE

    2009-05-01

    Full Text Available The use of energy crops (maize straw, wheat straw, barley straw etc. as substrate for renewable energy production (e.g. biogas is more efficient when it is degraded by different hydrolysis methods. However, fibers contained inside energy crops (e.g. cellulose and hemicellulose are only hardly and slowly degraded by anaerobic bacteria. The slow degradation of these substances can decrease the methane yields of agricultural biogas plants.In the present study, we investigated the efficiency of combined pretreatment (different concentrations H2SO4 + 30 minutes at 1210C followed to enzymatic hydrolysis. Testing different concentration of H2SO4, good results were obtained for maize whole crop when we used combined pretreatment (3% H2SO4 + 30 minutes at 1210C followed to enzymatic hydrolysis (3.9 fold higher and for Gavott Maize Straw when we used combined pretreatment (2% H2SO4 + 30 minutes at 1210C followed to enzymatic hydrolysis (3.6 fold higher comparing with untreated samples.

  12. Hydrolysis of native and heat-treated starches at sub-gelatinization temperature using granular starch hydrolyzing enzyme.

    Science.gov (United States)

    Uthumporn, U; Shariffa, Y N; Karim, A A

    2012-03-01

    The effect of heat treatment below the gelatinization temperature on the susceptibility of corn, mung bean, sago, and potato starches towards granular starch hydrolysis (35°C) was investigated. Starches were hydrolyzed in granular state and after heat treatment (50°C for 30 min) by using granular starch hydrolyzing enzyme for 24 h. Hydrolyzed heat-treated starches showed a significant increase in the percentage of dextrose equivalent compared to native starches, respectively, with corn 53% to 56%, mung bean 36% to 47%, sago 15% to 26%, and potato 12% to 15%. Scanning electron microscopy micrographs showed the presence of more porous granules and surface erosion in heat-treated starch compared to native starch. X-ray analysis showed no changes but with sharper peaks for all the starches, suggested that hydrolysis occurred on the amorphous region. The amylose content and swelling power of heat-treated starches was markedly altered after hydrolysis. Evidently, this enzyme was able to hydrolyze granular starches and heat treatment before hydrolysis significantly increased the degree of hydrolysis.

  13. Palladium(II)-Catalyzed meta-C-H Olefination: Constructing Multisubstituted Arenes through Homo-Diolefination and Sequential Hetero-Diolefination.

    Science.gov (United States)

    Bera, Milan; Maji, Arun; Sahoo, Santosh K; Maiti, Debabrata

    2015-07-13

    Divinylbenzene derivatives represent an important class of molecular building blocks in organic chemistry and materials science. Reported herein is the palladium-catalyzed synthesis of divinylbenzenes by meta-C-H olefination of sulfone-based arenes. Successful sequential olefinations in a position-selective manner provided a novel route for the synthesis of hetero-dialkenylated products, which are difficult to access using conventional methods. Additionally, 1,3,5-trialkenylated compounds can be generated upon successful removal of the directing group. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Structure of the N-terminal Gyrase B fragment in complex with ADP⋅Pi reveals rigid-body motion induced by ATP hydrolysis.

    Directory of Open Access Journals (Sweden)

    Frédéric V Stanger

    Full Text Available Type II DNA topoisomerases are essential enzymes that catalyze topological rearrangement of double-stranded DNA using the free energy generated by ATP hydrolysis. Bacterial DNA gyrase is a prototype of this family and is composed of two subunits (GyrA, GyrB that form a GyrA2GyrB2 heterotetramer. The N-terminal 43-kDa fragment of GyrB (GyrB43 from E. coli comprising the ATPase and the transducer domains has been studied extensively. The dimeric fragment is competent for ATP hydrolysis and its structure in complex with the substrate analog AMPPNP is known. Here, we have determined the remaining conformational states of the enzyme along the ATP hydrolysis reaction path by solving crystal structures of GyrB43 in complex with ADP⋅BeF3, ADP⋅Pi, and ADP. Upon hydrolysis, the enzyme undergoes an obligatory 12° domain rearrangement to accommodate the 1.5 Å increase in distance between the γ- and β-phosphate of the nucleotide within the sealed binding site at the domain interface. Conserved residues from the QTK loop of the transducer domain (also part of the domain interface couple the small structural change within the binding site with the rigid body motion. The domain reorientation is reflected in a significant 7 Å increase in the separation of the two transducer domains of the dimer that would embrace one of the DNA segments in full-length gyrase. The observed conformational change is likely to be relevant for the allosteric coordination of ATP hydrolysis with DNA binding, cleavage/re-ligation and/or strand passage.

  15. Enzymic lactose hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Miller, J J; Brand, J C

    1980-01-01

    Acid or enzymic hydrolysis can be used to hydrolyze lactose. Advantages of both are compared and details of enzymic hydrolysis using yeast or fungal enzymes given. The new scheme outlined involves recycling lactase. Because lactose and lactase react to ultrafiltration (UF) membranes differently separation is possible. Milk or milk products are ultrafiltered to separate a concentrate from a lactose-rich permeate which is treated with lactase in a reactor until hydrolysis reaches a required level. The lactase can be removed by UF as it does not permeate the membrane, and it is recycled back to the reactor. Permeate from the second UF stage may or may not be recombined with the concentrate from the first stage to produce a low lactose product (analysis of a typical low-lactose dried whole milk is given). Batch or continuous processes are explained and a batch process without enzyme recovery is discussed. (Refs. 4).

  16. Four Novel p.N385K, p.V36A, c.1033–1034insT and c.1417–1418delCT Mutations in the Sphingomyelin Phosphodiesterase 1 (SMPD1 Gene in Patients with Types A and B Niemann-Pick Disease (NPD

    Directory of Open Access Journals (Sweden)

    Masoumeh Dehghan Manshadi

    2015-03-01

    Full Text Available Background: Types A and B Niemann-Pick disease (NPD are autosomal-recessive lysosomal storage disorders caused by the deficient activity of acid sphingomyelinase due to mutations in the sphingomyelin phosphodiesterase 1 (SMPD1 gene. Methods: In order to determine the prevalence and distribution of SMPD1 gene mutations, the genomic DNA of 15 unrelated Iranian patients with types A and B NPD was examined using PCR, DNA sequencing and bioinformatics analysis. Results: Of 8 patients with the p.G508R mutation, 5 patients were homozygous, while the other 3 were heterozygous. One patient was heterozygous for both the p.N385K and p.G508R mutations. Another patient was heterozygous for both the p.A487V and p.G508R mutations. Two patients (one homozygous and one heterozygous showed the p.V36A mutation. One patient was homozygous for the c.1033–1034insT mutation. One patient was homozygous for the c.573delT mutation, and 1 patient was homozygous for the c.1417–1418delCT mutation. Additionally, bioinformatics analysis indicated that two new p.V36A and p.N385K mutations decreased the acid sphingomyelinase (ASM protein stability, which might be evidence to suggest the pathogenicity of these mutations. Conclusion: with detection of these new mutations, the genotypic spectrum of types A and B NPD is extended, facilitating the definition of disease-related mutations. However, more research is essential to confirm the pathogenic effect of these mutations.

  17. Cassava Pulp Hydrolysis under Microwave Irradiation with Oxalic Acid Catalyst for Ethanol Production

    Directory of Open Access Journals (Sweden)

    Euis Hermiati

    2014-07-01

    Full Text Available Microwave irradiation is an alternative method of starch hydrolysis that offers a rapid process. The aim of this research was to improve microwave-assisted hydrolysis of cassava pulp by using oxalic acid as a catalyst. Suspension of cassava pulp in 0.5% oxalic acid (1 g/20 mL was subjected to microwave irradiation at 140-230 °C for 5 minutes, with 4 minutes of pre-heating. One gram of fractured activated carbon made of coconut shell was added into a number of suspensions that were subjected to the same conditions of microwave irradiation. The soluble fraction of the hydrolysates was analyzed for its total soluble solids, malto-oligomer distribution, glucose content, pH value, and formation of brown compounds. The effects of the combined severity parameter at a substrate concentration of 5-12.5% on the glucose yield were also evaluated. The highest glucose yield (78% of dry matter was obtained after hydrolysis at 180 °C without activated carbon addition. Heating above 180 °C reduced the glucose yield and increased the pH and the formation of brown compounds. The use of activated carbon in microwave-assisted acid hydrolysis of cassava pulp reduced the glucose yield, but suppressed the formation of brown compounds. The highest glucose yield (70-80% of dry matter was attained at a severity parameter of 1.3-1.5.

  18. Characterization of silica particles prepared via urease-catalyzed urea hydrolysis and activity of urease in sol–gel silica matrix

    International Nuclear Information System (INIS)

    Kato, Katsuya; Nishida, Masakazu; Ito, Kimiyasu; Tomita, Masahiro

    2012-01-01

    Highlights: ► Silica precipitation occurred via urease-catalytic reactions. ► Higher urease activity for silica synthesis enables mesostructure of silica–urease composites. ► Urease encapsulating in silica matrix retained high activity. - Abstract: Urease templated precipitation of silica synthesized by sol–gel chemistry produces a composite material allowing high urease activity. This study investigates the structural properties of the composite material that allow for the retention of the urease hydrolysis activity. Scanning (SEM) and transmission (TEM) electron microscopy reveal that the composite has a mesoporous structure composed of closely packed spherical structures ∼20–50 nm in diameter. Brunauer–Emmett–Teller (BET) analysis revealed that the surface area and pore volume of the composite prepared under the conditions of 50 mM urea and 25 °C is relatively high (324 m 2 /g and 1.0 cm 3 /g). These values are equivalent to those of usual mesoporous silica materials synthesized from the self-assembly of triblock copolymers as organic templates. In addition, after encapsulating in a sol–gel silica matrix, urease retained high activity (∼90% of the activity compared with native urease). Our results suggest a new method for synthesizing mesoporous silica materials with highly tunable pore sizes and shapes under mild conditions.

  19. Effects of copper source and concentration on in vitro phytate phosphorus hydrolysis by phytase.

    Science.gov (United States)

    Pang, Yanfang; Applegate, Todd J

    2006-03-08

    Five copper (Cu) sources were studied at pH 2.5, 5.5, and 6.5 to determine how Cu affects phytate phosphorus (PP) hydrolysis by phytase at concentrations up to 500 mg/kg diet (60 min, 40-41 degrees C). Subsequently, Cu solubility with and without sodium phytate was measured. Adding Cu inhibited PP hydrolysis at pH 5.5 and pH 6.5 (P copper chloride and copper lysinate inhibited PP hydrolysis much less than copper sulfate pentahydrate, copper chloride, and copper citrate (P copper-phytin complexes.

  20. Conformational Footprint in Hydrolysis-Induced Nanofibrillation and Crystallization of Poly(lactic acid).

    Science.gov (United States)

    Xu, Huan; Yang, Xi; Xie, Lan; Hakkarainen, Minna

    2016-03-14

    The origin of hydrolysis-induced nanofibrillation and crystallization, at the molecular level, was revealed by mapping the conformational ordering during long-term hydrolytic degradation of initially amorphous poly(lactic acid) (PLA), a representative model for degradable aliphatic polyesters generally displaying strong interplay between crystallization and hydrolytic erosion. The conformational regularization of chain segments was essentially the main driving force for the morphological evolution of PLA during hydrolytic degradation. For hydrolysis at 37 °C, no significant structural variations were observed due to the immobilization of "frozen" PLA chains. In contrast, conformational ordering in PLA was immediately triggered during hydrolysis at 60 °C and was responsible for the transition from random coils to disordered trans and, further, to quasi-crystalline nanospheres. On the surfaces, the head-by-head absorption and joining of neighboring nanospheres led to nanofibrillar assemblies following a "gluttonous snake"-like manner. The length and density of nanofibers formed were in close relation to the hydrolytic evolution, both of which showed a direct rise in the initial 60 days and then a gradual decline. In the interior, presumably the high surface energy of the nanospheres allowed for the preferential anchoring and packing of conformationally ordered chains into lamellae. In accordance with the well-established hypothesis, the amorphous regions were attacked prior to the erosion of crystalline entities, causing a rapid increase of crystallinity during the initial 30 days, followed by a gradual fall until 90 days. In addition to adequate illustration of hydrolysis-induced variations of crystallinity, our proposed model elucidates the formation of spherulitic nuclei featuring an extremely wide distribution of diameters ranging from several nanometers to over 5 μm, as well as the inferior resistance to hydrolysis observed for the primary nuclei. Our work

  1. Hydrolysis of solubilized hemicellulose derived from wet-oxidized wheat straw by a mixture of commercial fungal enzyme preparations

    Energy Technology Data Exchange (ETDEWEB)

    Skammelsen Schmidt, Anette; Thomsen, Alle Belinda; Woidemann, Anders [Risoe National Lab. (Denmark); Tenkanen, Maija [VTT Biotechnology and Food Research (Finland)

    1998-04-01

    The enzymatic hydrolysis of the solubilized hemicellulose fraction from wet-oxidized wheat straw was investigated for quantification purposes. An optimal hydrolysis depends on factors such as composition of the applied enzyme mixture and the hydrolysis conditions (enzyme loading, hydrolysis time, pH-value, and temperature). A concentrated enzyme mixture was used in this study prepared at VTT Biotechnology and Food Research, Finland, by mixing four commercial enzyme preparations. No distinctive pH-value and temperature optima were identified after a prolonged incubation of 24 hours. By reducing the hydrolysis time to 2 hours a temperature optimum was found at 50 deg. C, where a pH-value higher than 5.2 resulted in reduced activity. An enzyme-substrate-volume-ratio of 0.042, a pH-value of 5.0, and a temperature of 50 deg. C were chosen as the best hydrolysis conditions due to an improved monosaccharide yield. The hydrolysis time was chosen to be 24 hours to ensure equilibrium and total quantification. Even under the best hydrolysis conditions, the overall sugar yield from the enzymatic hydrolysis was only 85% of that of the optimal acid hydrolysis. The glucose yield were approximately the same for the two types of hydrolyses, probably due to the high cellulase activity in the VTT-enzyme mixture. For xylose and arabinose the enzymatic hydrolysis yielded only 80% of that of the acid hydrolysis. As the pentoses existed mainly as complex polymers their degradation required many different enzymes, some of which might be missing from the VTT-enzyme mixture. Furthermore, the removal of side-choins from the xylan backbone during the wet-oxidation pretreatment process might enable the hemicellulosic polymers to interact and precipitate, hence, reducing the enzymatic digestibility of the hemicellulose. (au) 8 tabs., 10 ills., 65 refs.

  2. Hydrolysis of strained bridgehead bicyclic vinyl ethers and sulfides

    International Nuclear Information System (INIS)

    Chwang, W.K.; Kresge, A.J.; Wiseman, J.R.

    1979-01-01

    Rates of hydrolysis of the bridgehead bicyclic vinyl ether 9-oxabicyclo[3.3.1]non-1-ene(6) and its vinyl sulfide counterpart 9-thiabicyclo[3.3.1]non-1-ene(7), catalyzed by the hydronium ion, were measured in H 2 O and in D 2 O solution. These data give isotope effects, k/sub H//k/sub D/ = 2.4 and 1.9 respectively, which show that these reactions occur by the normal, rate-determining carbon protonation, mechanism. The vinyl ether 6 is less reactive than its olefin analogue, bicyclo[3.3.1]non-1-ene (relative rate 1:1/1400), as may have been expected for a constrained bicyclic system such as this, where stabilization of the bridgehead carbocation intermediate by conjugation with oxygen is severely impaired. The vinyl sulfide 7, however, is even less reactive than the vinyl ether (relative rates 1:1/140); this is a remarkable result in view of the fact that conjugation between the sulfur atom and the cationic center is presumably also strongly inhibited. 1 figure, 3 tables

  3. Nickel-Catalyzed C-S Bond Formation via Decarbonylative Thioetherification of Esters, Amides and Intramolecular Recombination Fragment Coupling of Thioesters

    KAUST Repository

    Lee, Shao-Chi

    2018-01-15

    A nickel catalyzed cross-coupling protocol for the straightforward C-S bond formation has been developed. Various mercaptans and a wide range of ester and amide substrates bearing various substituents were tolerated in this process which afforded products in good to excellent yields. Furthermore, an intramolecular protocol for the synthesis of thioethers starting from thioesters has been developed. The utility of this protocol has been demonstrated in the synthesis of benzothiophene on the bench top.

  4. Nickel-Catalyzed C-S Bond Formation via Decarbonylative Thioetherification of Esters, Amides and Intramolecular Recombination Fragment Coupling of Thioesters

    KAUST Repository

    Lee, Shao-Chi; Liao, Hsuan-Hung; Chatupheeraphat, Adisak; Rueping, Magnus

    2018-01-01

    A nickel catalyzed cross-coupling protocol for the straightforward C-S bond formation has been developed. Various mercaptans and a wide range of ester and amide substrates bearing various substituents were tolerated in this process which afforded products in good to excellent yields. Furthermore, an intramolecular protocol for the synthesis of thioethers starting from thioesters has been developed. The utility of this protocol has been demonstrated in the synthesis of benzothiophene on the bench top.

  5. Aerobic Asymmetric Dehydrogenative Cross-Coupling between Two C(sp3)-H Groups Catalyzed by a Chiral-at-Metal Rhodium Complex.

    Science.gov (United States)

    Tan, Yuqi; Yuan, Wei; Gong, Lei; Meggers, Eric

    2015-10-26

    A sustainable C-C bond formation is merged with the catalytic asymmetric generation of one or two stereocenters. The introduced catalytic asymmetric cross-coupling of two C(sp3)-H groups with molecular oxygen as the oxidant profits from the oxidative robustness of a chiral-at-metal rhodium(III) catalyst and exploits an autoxidation mechanism or visible-light photosensitized oxidation. In the latter case, the catalyst serves a dual function, namely as a chiral Lewis acid for catalyzing enantioselective enolate chemistry and at the same time as a visible-light-driven photoredox catalyst. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Adsorption of monocomponent enzymes in enzyme mixture analyzed quantitatively during hydrolysis of lignocellulose substrates.

    Science.gov (United States)

    Várnai, Anikó; Viikari, Liisa; Marjamaa, Kaisa; Siika-aho, Matti

    2011-01-01

    The adsorption of purified Trichoderma reesei cellulases (TrCel7A, TrCel6A and TrCel5A) and xylanase TrXyn11 and Aspergillus niger β-glucosidase AnCel3A was studied in enzyme mixture during hydrolysis of two pretreated lignocellulosic materials, steam pretreated and catalytically delignified spruce, along with microcrystalline cellulose (Avicel). The enzyme mixture was compiled to resemble the composition of commercial cellulase preparations. The hydrolysis was carried out at 35 °C to mimic the temperature of the simultaneous saccharification and fermentation (SSF). Enzyme adsorption was followed by analyzing the activity and the protein amount of the individual free enzymes in the hydrolysis supernatant. Most enzymes adsorbed quickly at early stages of the hydrolysis and remained bound throughout the hydrolysis, although the conversion reached was fairly high. Only with the catalytically oxidized spruce samples, the bound enzymes started to be released as the hydrolysis degree reached 80%. The results based on enzyme activities and protein assay were in good accordance. Copyright © 2010 Elsevier Ltd. All rights reserved.

  7. Effect of gelatinization and hydrolysis conditions on the selectivity of starch hydrolysis with alpha-amylase from Bacillus licheniformis

    NARCIS (Netherlands)

    Baks, T.; Bruins, M.E.; Matser, A.M.; Janssen, A.E.M.; Boom, R.M.

    2008-01-01

    Enzymatic hydrolysis of starch can be used to obtain various valuable hydrolyzates with different compositions. The effects of starch pretreatment, enzyme addition point, and hydrolysis conditions on the hydrolyzate composition and reaction rate during wheat starch hydrolysis with ¿-amylase from

  8. In Situ Formation of AgCo Stabilized on Graphitic Carbon Nitride and Concomitant Hydrolysis of Ammonia Borane to Hydrogen

    Directory of Open Access Journals (Sweden)

    Qi Wang

    2018-04-01

    Full Text Available The development of highly-efficient heterogeneous supported catalysts for catalytic hydrolysis of ammonia borane to yield hydrogen is of significant importance considering the versatile usages of hydrogen. Herein, we reported the in situ synthesis of AgCo bimetallic nanoparticles supported on g-C3N4 and concomitant hydrolysis of ammonia borane for hydrogen evolution at room temperature. The as-synthesized Ag0.1Co0.9/g-C3N4 catalysts displayed the highest turnover frequency (TOF value of 249.02 mol H2·(molAg·min−1 for hydrogen evolution from the hydrolysis of ammonia borane, which was higher than many other reported values. Furthermore, the Ag0.1Co0.9/g-C3N4 catalyst could be recycled during five consecutive runs. The study proves that Ag0.1Co0.9/g-C3N4 is a potential catalytic material toward the hydrolysis of ammonia borane for hydrogen production.

  9. Stability of commercial glucanase and β-glucosidase preparations under hydrolysis conditions

    Directory of Open Access Journals (Sweden)

    Oscar Rosales-Calderon

    2014-06-01

    Full Text Available The cost of enzymes makes enzymatic hydrolysis one of the most expensive steps in the production of lignocellulosic ethanol. Diverse studies have used commercial enzyme cocktails assuming that change in total protein concentration during hydrolysis was solely due to adsorption of endo- and exoglucanases onto the substrate. Given the sensitivity of enzymes and proteins to media conditions this assumption was tested by evaluating and modeling the protein concentration of commercial cocktails at hydrolysis conditions. In the absence of solid substrate, the total protein concentration of a mixture of Celluclast 1.5 L and Novozyme 188 decreased by as much as 45% at 50 °C after 4 days. The individual cocktails as well as a mixture of both were stable at 20 °C. At 50 °C, the protein concentration of Celluclast 1.5 was relatively constant but Novozyme 188 decreased by as much as 77%. It was hypothesized that Novozyme 188 proteins suffer a structural change at 50 °C which leads to protein aggregation and precipitation. Lyophilized β-glucosidase (P-β-glucosidase at 50 °C exhibited an aggregation rate which was successfully modeled using first order kinetics (R2 = 0.97. By incorporating the possible presence of chaperone proteins in Novozyme 188, the protein aggregation observed for this cocktail was successfully modeled (R2 = 0.96. To accurately model the increasing protein stability observed at high cocktail loadings, the model was modified to include the presence of additives in the cocktail (R2 = 0.98. By combining the measurement of total protein concentration with the proposed Novozyme 188 protein aggregation model, the endo- and exoglucanases concentration in the solid and liquid phases during hydrolysis can be more accurately determined. This methodology can be applied to various systems leading to optimization of enzyme loading by minimizing the excess of endo- and exoglucanases. In addition, the monitoring of endo- and exoglucanases

  10. Characterization and photoconductivity study of well-defined C60 terminated poly(tert-butyl acrylate-b-styrene)

    International Nuclear Information System (INIS)

    Yang Dong; Li Lang; Wang Changchun

    2004-01-01

    Atom transfer radical polymerization (ATRP) catalyzed by N,N',N',N'',N''-pentamethyldiethylenetriamine (PMDETA)/CuBr was performed to synthesize poly (tert-butyl acrylate) (PtBA-Br) with predesigned molecular weight and narrow polydispersity. Using the PtBA-Br as macroinitiator, the PtBA-block-PS copolymer was prepared through ATRP. After terminated bromine atom was converted to end-functional azide group (P(tBA-b-St)-N 3 ), C 60 end-capped PtBA-PS block copolymers (P(tBA-b-St)-C 60 ) were synthesized by reacting C 60 with P(tBA-b-St)-N 3 . GPC characterizations showed that C 60 was chemically bonded to the end of P(tBA-b-St) chain and the products were mono-substituted. FT-IR, UV-Vis measurements confirmed that hydrolysis of P(tBA-b-St)-C 60 resulted in amphiphilic C 60 end-capped PAA-PS block copolymers. In additional, the photoconductivity of P(tBA-b-St)-C 60 was measured

  11. Thermal conductivity characteristics of dewatered sewage sludge by thermal hydrolysis reaction.

    Science.gov (United States)

    Song, Hyoung Woon; Park, Keum Joo; Han, Seong Kuk; Jung, Hee Suk

    2014-12-01

    The purpose of this study is to quantify the thermal conductivity of sewage sludge related to reaction temperature for the optimal design of a thermal hydrolysis reactor. We continuously quantified the thermal conductivity of dewatered sludge related to the reaction temperature. As the reaction temperature increased, the dewatered sludge is thermally liquefied under high temperature and pressure by the thermal hydrolysis reaction. Therefore, the bound water in the sludge cells comes out as free water, which changes the dewatered sludge from a solid phase to slurry in a liquid phase. As a result, the thermal conductivity of the sludge was more than 2.64 times lower than that of the water at 20. However, above 200, it became 0.704 W/m* degrees C, which is about 4% higher than that of water. As a result, the change in physical properties due to thermal hydrolysis appears to be an important factor for heat transfer efficiency. Implications: The thermal conductivity of dewatered sludge is an important factor the optimal design of a thermal hydrolysis reactor. The dewatered sludge is thermally liquefied under high temperature and pressure by the thermal hydrolysis reaction. The liquid phase slurry has a higher thermal conductivity than pure water.

  12. Electrospray ionization mass spectrometry for the hydrolysis complexes of cisplatin : Implications for the hydrolysis process of platinum complexes

    NARCIS (Netherlands)

    Xie, Feifan; Colin, Pieter; Van Bocxlaer, Jan

    Non-enzyme-dependent hydrolysis of the drug cisplatin is important for its mode of action and toxicity. However, up until today, the hydrolysis process of cisplatin is still not completely understood. In the present study, the hydrolysis of cisplatin in an aqueous solution was systematically

  13. Hydrolysis of whey by whole cells of Kluyveromyces bulgaricus immobilized in calcium alginate gels in hen egg white

    Energy Technology Data Exchange (ETDEWEB)

    Decleire, M; Huynh, N van; Motte, J C; Cat, W de

    1985-10-01

    Whey hydrolysis was compared in column reactors containing whole yeast cells immobilized in Ca-alginate or in hen egg white in relation to cell US -galactosidase activity, flow rates, temperature and time. With cells of 1.3 U/mg dry weight (ONPG method) immobilized in Ca-alignate, 80% hydrolysis was obtained at 4 and 20C with, respectively 0.50 and 1.65 bed volume/H; the values were 0.2 and 0.74 with cells entrapped in hen egg white. When the flow rate was expressed as ml/H/g wet yeast, no significant difference was observed between both matrices and 80% hydrolysis was reached with a flow rate 1.7 and 5 according to the temperature. The best performance was achieved by the yeast egg white reactor. At 4C, hydrolysis deccreased by 10% after 13 days; by 20% after 17 days. The presence of lactose transport inhibitors in whey did not significantly influence lactose hydrolysis. (orig.).

  14. Acid hydrolysis of the biomass of resistant cellulose of thistle ''Onopordum nervosum boiss''

    International Nuclear Information System (INIS)

    Suarez, C.; Diaz Palma, A.; Paz Saa, M.D.

    1985-01-01

    Hydrolysis of resistant cellulose of ''Onopordum nervosum boiss'' (thistle) to reduce sugar in diluted sulfuric acid in glass ampoules and long residence times have been studied and kinetic parameters determined. The rate of hydrolysis is similar to that of the cellulose of Douglas fir, but comparatively the effect of the acid is more pronounced than temperature. From kinetic data the yield can be predicted and since it can be obtained at least 45% of the potential glucose (48% as reducing sugars) at 190 deg C, 1.6% acid and 6.1 min. residence time, it indicates that the continuous acid hydrolysis of thistle may be a process of commercial interest. (author)

  15. Direct Synthesis of Protoberberine Alkaloids by Rh-Catalyzed C-H Bond Activation as the Key Step.

    Science.gov (United States)

    Jayakumar, Jayachandran; Cheng, Chien-Hong

    2016-01-26

    A one-pot reaction of substituted benzaldehydes with alkyne-amines by a Rh-catalyzed C-H activation and annulation to afford various natural and unnatural protoberberine alkaloids is reported. This reaction provides a convenient route for the generation of a compound library of protoberberine salts, which recently have attracted great attention because of their diverse biological activities. In addition, pyridinium salt derivatives can also be formed in good yields from α,β-unsaturated aldehydes and amino-alkynes. This reaction proceeds with excellent regioselectivity and good functional group compatibility under mild reaction conditions by using O2 as the oxidant. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Swelling and hydrolysis kinetics of Kraft pulp fibers in aqueous 1-butyl-3-methylimidazolium hydrogen sulfate solutions.

    Science.gov (United States)

    Mao, Jia; Abushammala, Hatem; Pereira, Laura Barcellos; Laborie, Marie-Pierre

    2016-11-20

    1Butyl-3-methylimidazolium hydrogen sulfate ([Bmim]HSO4) is efficient at extracting cellulose nanocrystals from pulp fibers. To shed some light on the respective contributions of swelling and hydrolysis of pulp fibers by [Bmim]HSO4, the physical, structural and morphological characteristics of hardwood Kraft pulp fibers were monitored under various conditions of temperature, water content and time. Swelling was largely compounded by hydrolysis at the highest temperatures (120°C) as evidenced by mass loss and reduced degree of polymerization (DPn) at this temperature. At 120°C only, water content appeared to play a significant role on the extent of hydrolysis. At this temperature, a heterogeneous kinetic model involving weak links and amorphous regions best described the experimental data. Hydrolysis rates were maximum at 25% water content in the aqueous ionic liquid. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Response surface optimization of enzymatic hydrolysis of narrow-leaf cattail for bioethanol production

    International Nuclear Information System (INIS)

    Ruangmee, Arrisa; Sangwichien, Chayanoot

    2013-01-01

    Highlights: • The cellulose of pretreated sample was higher than untreated sample. • Lower hemicellulose and lignin were enhanced of hydrolyzed cellulose to sugar. • The predicted result of enzymatic hydrolysis process was fitted by quadratic model. • Predicted data was good agreement with the experimental data; with 95% confidence. - Abstract: Narrow-leaf cattail was employed as lignocellulosic biomass substrate for the investigation of the hydrolysis process of lignocellulosic ethanol. Cellulose saccharification into a high yield of fermentable sugar is an important step in ethanol production. Response surface methodology was utilized in the study of variables affecting enzymatic hydrolysis on the released glucose and xylose. Five levels (−2, −1, 0, +1, +2) of independent variable factors; cellulase (5–25 FPU/g substrate), β-glucosidase (0–20 U/g substrate), hydrolysis temperature (30–50 °C), and hydrolysis time (24–96 h), were randomly setup by using the Design of Experiment program. The significance of the regression model was high; with 95% confidence interval (less than 5% error). The predicted result after optimization was also in good agreement with the experimental data. An optimal condition; 13.50 FPU/g substrate, 16.50 U/g substrate, 50 °C and 24 h, was obtained, yielding a released glucose of 552.9 mg/g substrate (75.6% saccharification) and a released xylose of 74.0 mg/g substrate (45.6% saccharification)

  18. Optimization of Enzymatic Hydrolysis of Waste Bread before Fermentation

    Directory of Open Access Journals (Sweden)

    Helena Hudečková

    2017-01-01

    Full Text Available Finding of optimal hydrolysis conditions is important for increasing the yield of saccharides. The higher yield of saccharides is usable for increase of the following fermentation effectivity. In this study optimal conditions (pH and temperature for amylolytic enzymes were searched. As raw material was used waste bread. Two analytical methods for analysis were used. Efficiency and process of hydrolysis was analysed spectrophotometrically by Somogyi-Nelson method. Final yields of glucose were analysed by HPLC. As raw material was used waste bread from local cafe. Waste bread was pretreated by grinding into small particles. Hydrolysis was performed in 100 mL of 15 % (w/v waste bread particles in the form of water suspension. Waste bread was hydrolysed by two commercial enzymes. For the liquefaction was used α‑amylase (BAN 240 L. The saccharification was performed by glucoamylase (AMG 300 L. Optimal conditions for α‑amylase (pH 6; 80 °C were found. The yield of total sugars was 67.08 g∙L-1 (calculated to maltose. As optimal conditions for glucoamylase (pH 4.2; 60 °C were found. Amount of glucose was 70.28 g∙L1. The time of waste bread liquefaction was 180 minutes. The time of saccharification was 90 minutes. The results were presented at the conference CECE Junior 2014.

  19. Effect of gelatinization and hydrolysis conditions on the selectivity of starch hydrolysis with alpha-amylase from Bacillus licheniformis.

    Science.gov (United States)

    Baks, Tim; Bruins, Marieke E; Matser, Ariette M; Janssen, Anja E M; Boom, Remko M

    2008-01-23

    Enzymatic hydrolysis of starch can be used to obtain various valuable hydrolyzates with different compositions. The effects of starch pretreatment, enzyme addition point, and hydrolysis conditions on the hydrolyzate composition and reaction rate during wheat starch hydrolysis with alpha-amylase from Bacillus licheniformis were compared. Suspensions of native starch or starch gelatinized at different conditions either with or without enzyme were hydrolyzed. During hydrolysis, the oligosaccharide concentration, the dextrose equivalent, and the enzyme activity were determined. We found that the hydrolyzate composition was affected by the type of starch pretreatment and the enzyme addition point but that it was just minimally affected by the pressure applied during hydrolysis, as long as gelatinization was complete. The differences between hydrolysis of thermally gelatinized, high-pressure gelatinized, and native starch were explained by considering the granule structure and the specific surface area of the granules. These results show that the hydrolyzate composition can be influenced by choosing different process sequences and conditions.

  20. Rh(III)-Catalyzed C-H Activation of Benzoylacetonitriles and Tandem Cyclization with Diazo Compounds to Substituted Benzo[ de]chromenes.

    Science.gov (United States)

    Fang, Feifei; Zhang, Chunmei; Zhou, Chaofan; Li, Yazhou; Zhou, Yu; Liu, Hong

    2018-04-06

    Rh (III)-catalyzed C-H activation of benzoylacetonitriles in coupling with diazo compounds was developed to synthesize diversified substituted benzo[ de]chromenes via a formal (4 + 2) cycloaddition with a diazo compound and subsequent tandem (4 + 2) cycloaddition with another diazo compound. Intriguingly, synthesis of substituted benzo[ de]chromenes and their decarboxylation products could be realized by controlling the reaction conditions. These reactions have a broad range of substrates, moderate to good yields, and high regioselectivity.

  1. Evaluation of hyper thermal acid hydrolysis of Kappaphycus alvarezii for enhanced bioethanol production.

    Science.gov (United States)

    Ra, Chae Hun; Nguyen, Trung Hau; Jeong, Gwi-Taek; Kim, Sung-Koo

    2016-06-01

    Hyper thermal (HT) acid hydrolysis of Kappaphycus alvarezii, a red seaweed, was optimized to 12% (w/v) seaweed slurry content, 180mM H2SO4 at 140°C for 5min. The maximum monosaccharide concentration of 38.3g/L and 66.7% conversion from total fermentable monosaccharides of 57.6g/L with 120gdw/L K. alvarezii slurry were obtained from HT acid hydrolysis and enzymatic saccharification. HT acid hydrolysis at a severity factor of 0.78 efficiently converted the carbohydrates of seaweed to monosaccharides and produced a low concentration of inhibitory compounds. The levels of ethanol production by separate hydrolysis and fermentation with non-adapted and adapted Kluyveromyces marxianus to high concentration of galactose were 6.1g/L with ethanol yield (YEtOH) of 0.19 at 84h and 16.0g/L with YEtOH of 0.42 at 72h, respectively. Development of the HT acid hydrolysis process and adapted yeast could enhance the overall ethanol fermentation yields of K. alvarezii seaweed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. A kinetic mechanistic study of acid-catalyzed alkylation of isobutane with C4-olefins at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Doshi, B.M.

    1978-01-01

    A kinetic and mechanistic study of sulfuric acid-catalyzed alkylation of isobutane with C/sub 4/-Olefins at Low Temperatures(-20/sup 0/ to 0/sup 0/C) was based on a new two-step reaction sequence in which the desired first-step reactions are between acid and olefin to form sulfates and the desired second-step reactions are between sulfates and isobutane to form mostly trimethylpentanes. Linear butenes formed stable sulfates that formed alkylates of exceptionally high quality, up to 100 Research octane, whereas isobutylene and trimethylpentene mainly polymerized during the first step, and the alkylate produced had only 90 Research octane. Trimethylpentanes and dimethylhexanes, when contacted with concentrated sulfuric acid at -10/sup 0/ to +25/sup 0/C, degraded and isomerized to form C/sub 4/-C/sub 9/ and higher isoparaffins and acid-soluble hydrocarbons (conjunct polymers). For the two-step process and the degradation and isomerization reactions, kinetic models based on reaction at the interface were developed; but for isoolefins, a polymerization-cracking sequence (via C/sub 12/- and even C/sub 16/-olefins) is the preferred route. Commercial applications of the results are proposed.

  3. The effect of pH, temperature and plaque thickness on the hydrolysis of monofluorophosphate in experimental dental plaque.

    Science.gov (United States)

    Pearce, E I F; Dibdin, G H

    2003-01-01

    Monofluorophosphate (MFP), an anti-caries agent commonly used in toothpaste, is known to be degraded to fluoride and orthophosphate by bacterial phosphatases in dental plaque. We have examined the effect of pH, temperature, plaque thickness and some ions on this process. Both natural plaque and artificial microcosm plaque incubated with purified MFP at pH 4-10 showed an optimum pH of approximately 8 for hydrolysis. Diffusion and concomitant hydrolysis were examined in an apparatus in which artificial plaque was held between rigid membranes separating two chambers. When MFP diffused through a plaque of 0.51-mm thickness over 4 h it was almost completely hydrolysed at pH 8, but hydrolysis on diffusion decreased as the pH deviated from 8. MFP in toothpaste extract showed a similar pH susceptibility to hydrolysis, according to the inherent pH of the toothpaste. Hydrolysis of MFP in the toothpaste was reduced by no more than 10% when compared with a matched-pH control, suggesting that other toothpaste ingredients had no major influence on hydrolysis. Transport was slower and hydrolysis at pH 6 more complete the thicker the plaque, but hydrolysis was not significantly slower at 23 degrees C than at 37 degrees C. The addition of various potential activating or inhibiting ions at 0.1 and 1.0 mmol/l had small and non-significant effects on hydrolysis. The results suggest that MFP toothpaste should be formulated and used to maximise enzymic hydrolysis of this complex anion, and that plaque pH control is probably the most important factor. Copyright 2003 S. Karger AG, Basel

  4. Effects of microtubule mechanics on hydrolysis and catastrophes

    International Nuclear Information System (INIS)

    Müller, N; Kierfeld, J

    2014-01-01

    We introduce a model for microtubule (MT) mechanics containing lateral bonds between dimers in neighboring protofilaments, bending rigidity of dimers, and repulsive interactions between protofilaments modeling steric constraints to investigate the influence of mechanical forces on hydrolysis and catastrophes. We use the allosteric dimer model, where tubulin dimers are characterized by an equilibrium bending angle, which changes from 0 ∘ to 22 ∘ by hydrolysis of a dimer. This also affects the lateral interaction and bending energies and, thus, the mechanical equilibrium state of the MT. As hydrolysis gives rise to conformational changes in dimers, mechanical forces also influence the hydrolysis rates by mechanical energy changes modulating the hydrolysis rate. The interaction via the MT mechanics then gives rise to correlation effects in the hydrolysis dynamics, which have not been taken into account before. Assuming a dominant influence of mechanical energies on hydrolysis rates, we investigate the most probable hydrolysis pathways both for vectorial and random hydrolysis. Investigating the stability with respect to lateral bond rupture, we identify initiation configurations for catastrophes along the hydrolysis pathways and values for a lateral bond rupture force. If we allow for rupturing of lateral bonds between dimers in neighboring protofilaments above this threshold force, our model exhibits avalanche-like catastrophe events. (papers)

  5. Hydrolysis of ferric chloride in solution

    International Nuclear Information System (INIS)

    Lussiez, G.; Beckstead, L.

    1996-11-01

    The Detox trademark process uses concentrated ferric chloride and small amounts of catalysts to oxidize organic compounds. It is under consideration for oxidizing transuranic organic wastes. Although the solution is reused extensively, at some point it will reach the acceptable limit of radioactivity or maximum solubility of the radioisotopes. This solution could be cemented, but the volume would be increased substantially because of the poor compatibility of chlorides and cement. A process has been developed that recovers the chloride ions as HCl and either minimizes the volume of radioactive waste or permits recycling of the radioactive chlorides. The process involves a two-step hydrolysis at atmospheric pressure, or preferably under a slight vacuum, and relatively low temperature, about 200 degrees C. During the first step of the process, hydrolysis occurs according to the reaction below: FeCl 3 liquid + H 2 O → FeOCl solid + 2 HCl gas During the second step, the hot, solid, iron oxychloride is sprayed with water or placed in contact with steam, and hydrolysis proceeds to the iron oxide according to the following reaction: 2 FeOCl solid + H 2 O → Fe 2 O 3 solid + 2 HCl gas . The iron oxide, which contains radioisotopes, can then be disposed of by cementation or encapsulation. Alternately, these chlorides can be washed off of the solids and can then either be recycled or disposed of in some other way

  6. Enzymatic hydrolysis and fermentation of agricultural residues to ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Mes-Hartree, M.; Hogan, C.M.; Saddler, J.N.

    1984-01-01

    A combined enzymatic hydrolysis and fermentation process was used to convert steam-treated wheat and barley straw to ethanol. Maximum conversion efficiencies were obtained when the substrates were steamed for 90 s. These substrates could yield over 0.4 g ethanol/g cellulose following a combined enzymatic hydrolysis and fermentation process procedure using culture filtrates derived from Trichoderma harzianum E58. When culture filtrates from Trichoderma reesei C30 and T. reesei QM9414 were used, the ethanol yields obtained were 0.32 and 0.12 g ethanol/g cellulose utilized, respectively. The lower ethanol yields obtained with these strains were attributed to the lower amounts of ..beta..-glucosidase detected in the T. reesei culture filtrates.

  7. Enantioselective Copper-Catalyzed Carboetherification of Unactivated Alkenes**

    Science.gov (United States)

    Bovino, Michael T.; Liwosz, Timothy W.; Kendel, Nicole E.; Miller, Yan; Tyminska, Nina

    2014-01-01

    Chiral saturated oxygen heterocycles are important components of bioactive compounds. Cyclization of alcohols onto pendant alkenes is a direct route to their synthesis, but few catalytic enantioselective methods enabling cyclization onto unactivated alkenes exist. Herein is reported a highly efficient copper-catalyzed cyclization of γ-unsaturated pentenols that terminates in C-C bond formation, a net alkene carboetherification. Both intra- and intermolecular C-C bond formations are demonstrated, yielding functionalized chiral tetrahydrofurans as well as fused-ring and bridged-ring oxabicyclic products. Transition state calculations support a cis-oxycupration stereochemistry-determining step. PMID:24798697

  8. Hydrolysis of short-chain phosphatidylcholines by bee venom phospholipase A2.

    Science.gov (United States)

    Raykova, D; Blagoev, B

    1986-01-01

    In order to find out the aggregation state of the substrate, preferred by bee venom phospholipase A2 (EC 3.1.1.4), its action on short-chain phosphatidylcholines with two identical (C6-C10) fatty acids has been tested. The rate of hydrolysis as a function of acyl chain length showed a maximum at dioctanoylphosphatidylcholine. The effects of alcohols, NaCl and Triton X-100, which affect the aggregation state of phospholipids in water, were also studied. The addition of n-alcohol led to a significant inhibition of the hydrolysis of the substrates present in micellar form and activated the hydrolysis of substrates which form liposomes. The inhibitory effect increased with increasing length of the aliphatic carbon chain of the alcohol. Triton X-100 at low Triton/phospholipid molar ratios enhanced enzyme activity. These results do not agree with the accepted idea that bee venom phospholipase A2 hydrolyzes short-chain lecithins in their molecularly dispersed form and that micelles cannot act as substrates. The data indicate that short-chain lecithins in the aggregated state are hydrolyzed and that the requirements of bee venom phospholipase A2 for the aggregation state of the substrate are not strict.

  9. Rhodium-catalyzed C-H bond activation for the synthesis of quinonoid compounds: Significant Anti-Trypanosoma cruzi activities and electrochemical studies of functionalized quinones.

    Science.gov (United States)

    Jardim, Guilherme A M; Silva, Thaissa L; Goulart, Marilia O F; de Simone, Carlos A; Barbosa, Juliana M C; Salomão, Kelly; de Castro, Solange L; Bower, John F; da Silva Júnior, Eufrânio N

    2017-08-18

    Thirty four halogen and selenium-containing quinones, synthesized by rhodium-catalyzed C-H bond activation and palladium-catalyzed cross-coupling reactions, were evaluated against bloodstream trypomastigotes of T. cruzi. We have identified fifteen compounds with IC 50 /24 h values of less than 2 μM. Electrochemical studies on A-ring functionalized naphthoquinones were also performed aiming to correlate redox properties with trypanocidal activity. For instance, (E)-5-styryl-1,4-naphthoquinone 59 and 5,8-diiodo-1,4-naphthoquinone 3, which are around fifty fold more active than the standard drug benznidazole, are potential derivatives for further investigation. These compounds represent powerful new agents useful in Chagas disease therapy. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  10. SIMULTANEOUS PRETREATMENT OF LIGNOCELLULOSE AND HYDROLYSIS OF STARCH IN MIXTURES TO SUGARS

    OpenAIRE

    Hamzeh Hoseinpour; Keikhosro Karimi; Hamid Zilouei; Mohammad J. Taherzadeh

    2010-01-01

    Mixtures of starch and lignocelluloses are available in many industrial, agricultural, and municipal wastes and residuals. In this work, dilute sulfuric acid was used for simultaneous pretreatment of lignocellulose and hydrolysis of starch, to obtain a maximum amount of fermentable sugar after enzymatic hydrolysis with cellulase and β-glucosidase. The acid treatment was carried out at 70-150°C with 0-1% (v/v) acid concentration and 5-15% (w/v) solids concentration for 0-40 minutes. Under the ...

  11. Synthesis of Donor/Acceptor-Substituted Diazo Compounds in Flow and Their Application in Enantioselective Dirhodium-Catalyzed Cyclopropanation and C-H Functionalization.

    Science.gov (United States)

    Rackl, Daniel; Yoo, Chun-Jae; Jones, Christopher W; Davies, Huw M L

    2017-06-16

    A tandem reaction system has been developed for the preparation of donor/acceptor-substituted diazo compounds in continuous flow coupled to dirhodium-catalyzed C-H functionalization or cyclopropanation. Hydrazones were oxidized in flow by solid-supported N-iodo-p-toluenesulfonamide potassium salt (PS-SO 2 NIK) to generate the diazo compounds, which were then purified by passing through a column of molecular sieves/sodium thiosulfate.

  12. Kinetics of Strong Acid Hydrolysis of a Bleached Kraft Pulp for Producing Cellulose Nanocrystals (CNCs)

    Science.gov (United States)

    Qianqian Wang; Xuebing Zhao; J.Y. Zhu

    2014-01-01

    Cellulose nanocrytals (CNCs) are predominantly produced using the traditional strong acid hydrolysis process. In most reported studies, the typical CNC yield is low (approximately 30%) despite process optimization. This study investigated the hydrolysis of a bleached kraft eucalyptus pulp using sulfuric acid between 50 and 64 wt % at temperatures of 35−80 °C...

  13. Remote C−H Activation of Quinolines through Copper-Catalyzed Radical Cross-Coupling

    KAUST Repository

    Xu, Jun

    2016-01-12

    Achieving site selectivity in carbon-hydrogen (C-H) functionalization reactions is a formidable challenge in organic chemistry. Herein, we report a novel approach to activating remote C-H bonds at the C5 position of 8-aminoquinoline through copper-catalyzed sulfonylation under mild conditions. Our strategy shows high conversion efficiency, a broad substrate scope, and good toleration with different functional groups. Furthermore, our mechanistic investigations suggest that a single-electron-transfer process plays a vital role in generating sulfonyl radicals and subsequently initiating C-S cross-coupling. Importantly, our copper-catalyzed remote functionalization protocol can be expanded for the construction of a variety of chemical bonds, including C-O, C-Br, C-N, C-C, and C-I. These findings provide a fundamental insight into the activation of remote C-H bonds, while offering new possibilities for rational design of drug molecules and optoelectronic materials requiring specific modification of functional groups. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Ruthenium(II)-Catalyzed C-H Activation of Imidamides and Divergent Couplings with Diazo Compounds: Substrate-Controlled Synthesis of Indoles and 3H-Indoles.

    Science.gov (United States)

    Li, Yunyun; Qi, Zisong; Wang, He; Yang, Xifa; Li, Xingwei

    2016-09-19

    Indoles are an important structural motif that is commonly found in biologically active molecules. In this work, conditions for divergent couplings between imidamides and acceptor-acceptor diazo compounds were developed that afforded NH indoles and 3H-indoles under ruthenium catalysis. The coupling of α-diazoketoesters afforded NH indoles by cleavage of the C(N2 )-C(acyl) bond whereas α-diazomalonates gave 3H-indoles by C-N bond cleavage. This reaction constitutes the first intermolecular coupling of diazo substrates with arenes by ruthenium-catalyzed C-H activation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. THE DECEPTIVELY SIMPLE THERMOLYSIS OF TRIVALENT PERMETHYLTITANOCENE DERIVATIVES (ETA-5-C5ME5)2TIR - FORMATION OF A TETRAMETHYLFULVENE TITANIUM COMPOUND (ETA-6-C5ME4CH2)(ETA-5-C5ME5)TI AND RH, CATALYZED BY PERMETHYLTITANOCENE HYDRIDE, (ETA-5-C5ME5)2TIH

    NARCIS (Netherlands)

    LUINSTRA, GA; TEUBEN, JH

    1992-01-01

    The complexes Cp*2TiR (Cp* = eta-5-C5Me5; R = Me, Et, n-Pr, C2H3, CH2CMe3, Ph) undergo thermolysis to yield the fulvene complex Cp*FvTi (Fv = eta-6-C5Me4CH2) and RH. Kinetic measurements and deuterium labeling studies show that the decomposition is catalyzed by Cp*2TiH, which is formed either by

  16. Modeling enzymatic hydrolysis of lignocellulosic substrates using confocal fluorescence microscopy I: filter paper cellulose.

    Science.gov (United States)

    Luterbacher, Jeremy S; Moran-Mirabal, Jose M; Burkholder, Eric W; Walker, Larry P

    2015-01-01

    Enzymatic hydrolysis is one of the critical steps in depolymerizing lignocellulosic biomass into fermentable sugars for further upgrading into fuels and/or chemicals. However, many studies still rely on empirical trends to optimize enzymatic reactions. An improved understanding of enzymatic hydrolysis could allow research efforts to follow a rational design guided by an appropriate theoretical framework. In this study, we present a method to image cellulosic substrates with complex three-dimensional structure, such as filter paper, undergoing hydrolysis under conditions relevant to industrial saccharification processes (i.e., temperature of 50°C, using commercial cellulolytic cocktails). Fluorescence intensities resulting from confocal images were used to estimate parameters for a diffusion and reaction model. Furthermore, the observation of a relatively constant bound enzyme fluorescence signal throughout hydrolysis supported our modeling assumption regarding the structure of biomass during hydrolysis. The observed behavior suggests that pore evolution can be modeled as widening of infinitely long slits. The resulting model accurately predicts the concentrations of soluble carbohydrates obtained from independent saccharification experiments conducted in bulk, demonstrating its relevance to biomass conversion work. © 2014 Wiley Periodicals, Inc.

  17. Manganese Catalyzed Regioselective C–H Alkylation: Experiment and Computation

    KAUST Repository

    Wang, Chengming

    2018-05-08

    A new efficient manganese-catalyzed selective C2-alkylation of indoles via carbenoid insertion has been achieved. The newly developed C-H functionalization protocol provides access to diverse products and shows good functional group tolerance. Mechanistic and computational studies support the formation of a Mn(CO)3 acetate complex as the catalytically active species.

  18. Manganese Catalyzed Regioselective C–H Alkylation: Experiment and Computation

    KAUST Repository

    Wang, Chengming; Maity, Bholanath; Cavallo, Luigi; Rueping, Magnus

    2018-01-01

    A new efficient manganese-catalyzed selective C2-alkylation of indoles via carbenoid insertion has been achieved. The newly developed C-H functionalization protocol provides access to diverse products and shows good functional group tolerance. Mechanistic and computational studies support the formation of a Mn(CO)3 acetate complex as the catalytically active species.

  19. Preparation of Benzo[c]carbazol-6-amines via Manganese-Catalyzed Enaminylation of 1-(Pyrimidin-2-yl)-1H-indoles with Ketenimines and Subsequent Oxidative Cyclization.

    Science.gov (United States)

    Zhou, Xiaorong; Li, Zhenmin; Zhang, Zhiyin; Lu, Ping; Wang, Yanguang

    2018-03-02

    Manganese-catalyzed C 2 -H enaminylation of 1-(pyrimidin-2-yl)-1H-indoles with ketenimines is reported. The reaction provided 2-enaminylated indole derivatives in moderate to excellent yields with a broad substrate scope. A migration of the directing group pyrimidinyl occurred during this process. The synthesized 2-enaminyl indoles could be conveniently converted into 5-aryl-7H-benzo[c]carbazol-6-amines.

  20. Pretreatment by radiation and acids of chaff and its effect on enzymatic hydrolysis of cellulose

    International Nuclear Information System (INIS)

    Kumakura, M.; Kaetsu, I.

    1984-01-01

    The effect of pretreatment by radiation and acids—sulfuric, hydrochloric and acetic—on the enzymatic hydrolysis of chaff was studied. The combination of radiation and acids accelerates subsequent crushing and enzymatic hydrolysis. The percentage of fine powder below 115 mesh, after the crushing and the glucose yield on subsequent enzymatic hydrolysis, increased with increasing acid concentration, treatment time and irradiation dose. Radiation and hydrochloric acid pretreatment was the most effective in giving a high glucose conversion yield (about 90%). Irradiation dose, acid concentration, treatment temperature and treatment time were 20 Mrad, 0·5%, 70°C, and 5 h, respectively

  1. Development of a second generation palladium-catalyzed cycloalkenylation and its application to bioactive natural product synthesis.

    Science.gov (United States)

    Toyota, Masahiro

    2013-07-01

    A novel palladium-catalyzed intramolecular oxidative alkylation of unactivated olefins is described. This protocol was devised to solve one of the drawbacks of the original palladium-catalyzed cycloalkenylation that we developed. We call this new procedure the 'second generation palladium-catalyzed cycloalkenylation'. This protocol has been applied to the total syntheses of cis-195A, trans-195A, boonein, scholareins A, C, D, and alpha-skytanthine.

  2. Enantioselective [3+3] atroposelective annulation catalyzed by N-heterocyclic carbenes

    KAUST Repository

    Zhao, Changgui

    2018-02-05

    Axially chiral molecules are among the most valuable substrates in organic synthesis. They are typically used as chiral ligands or catalysts in asymmetric reactions. Recent progress for the construction of these chiral molecules is mainly focused on the transition-metal-catalyzed transformations. Here, we report the enantioselective NHC-catalyzed (NHC: N-heterocyclic carbenes) atroposelective annulation of cyclic 1,3-diones with ynals. In the presence of NHC precatalyst, base, Lewis acid and oxidant, a catalytic C–C bond formation occurs, providing axially chiral α-pyrone−aryls in moderate to good yields and with high enantioselectivities. Control experiments indicated that alkynyl acyl azoliums, acting as active intermediates, are employed to atroposelectively assemble chiral biaryls and such a methodology may be creatively applied to other useful NHC-catalyzed asymmetric transformations.

  3. CU(II): catalyzed hydrazine reduction of ferric nitrate

    International Nuclear Information System (INIS)

    Karraker, D.G.

    1981-11-01

    A method is described for producing ferrous nitrate solutions by the cupric ion-catalyzed reduction of ferric nitrate with hydrazine. The reaction is complete in about 1.5 hours at 40 0 C. Hydrazoic acid is also produced in substantial quantities as a reaction byproduct

  4. Hydrolysis Batteries: Generating Electrical Energy during Hydrogen Absorption.

    Science.gov (United States)

    Xiao, Rui; Chen, Jun; Fu, Kai; Zheng, Xinyao; Wang, Teng; Zheng, Jie; Li, Xingguo

    2018-02-19

    The hydrolysis reaction of aluminum can be decoupled into a battery by pairing an Al foil with a Pd-capped yttrium dihydride (YH 2 -Pd) electrode. This hydrolysis battery generates a voltage around 0.45 V and leads to hydrogen absorption into the YH 2 layer. This represents a new hydrogen absorption mechanism featuring electrical energy generation during hydrogen absorption. The hydrolysis battery converts 8-15 % of the thermal energy of the hydrolysis reaction into usable electrical energy, leading to much higher energy efficiency compared to that of direct hydrolysis. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Scope and Limitations of Auxiliary-Assisted, Palladium-Catalyzed Arylation and Alkylation of sp2 and sp3 C-H Bonds

    Science.gov (United States)

    Nadres, Enrico T.; Santos, Gerson Ivan Franco; Shabashov, Dmitry; Daugulis, Olafs

    2013-01-01

    The scope of palladium-catalyzed, auxiliary-assisted direct arylation and alkylation of sp2 and sp3 C-H bonds of amine and carboxylic acid derivatives has been investigated. The method employs a palladium acetate catalyst, substrate, aryl, alkyl, benzyl, or allyl halide, and inorganic base in t-amyl alcohol or water solvent at 100-140 °C. Aryl and alkyl iodides as well as benzyl and allyl bromides are competent reagents in this transformation. Picolinic acid auxiliary is used for amine γ-functionalization and 8-aminoquinoline auxiliary is used for carboxylic acid β-functionalization. Some optimization of base, additives, and solvent is required for achieving best results. PMID:24090404

  6. Effect of the steam explosion pretreatment on enzymatic hydrolysis of eucalyptus wood and sweet sorghum bagasse

    International Nuclear Information System (INIS)

    Negro, M.J.; Martinez, J.M.; Manero, J.; Saez, F.; Martin, C.

    1990-01-01

    The effect of steam explosion treatment on the enzymatic hydrolysis yield of two different lignocellulosic substrates is studied. Raw materials have been pretreated in a pilot plant designed to work in batch and equiped with a reactor vessel of 2 1 working volume where biomass was heated at the desired temperature and then exploded and recovered in a cyclone. Temperatures from 190 to 230 o C and reaction times from 2 to 8 min. have been assayed. The efficiency of the steam explosion treatment has been evaluated on the composition of the lignocellulosic materials as well as on their enzymatic hydrolysis yield using a cellulolytic complex from T. reesei. Results show a high solubilization rate of hemicelluloses ands variable losses of cellulose and lignin depending on the conditions tested. Enzymatic hydrolysis yields of both substrates experimented remarkable increments, correspondig the highest values obtained to 210 o C; 2 min. and 210 o C; 4 min. for sorghum bagasse and eucaliptus wood respectivelly. (Author). 13 refs

  7. Transport and metabolism of a sucrose analog (1'-fluorosucrose) into Zea mays L. Endosperm without invertase hydrolysis

    International Nuclear Information System (INIS)

    Schmalstig, J.G.; Hitz, W.D.

    1987-01-01

    1'-fluorosucrose (FS), a sucrose analog resistant to hydrolysis by invertase, was transported from husk leaves into maize (Zea mays L.) kernels with the same magnitude and kinetics as sucrose. 14 C-Label from [ 14 C]FS and [ 14 C]sucrose in separate experiments was distributed similarly between the pedicel, endosperm, and embryo with time. FS passed through maternal tissue and was adsorbed intact into the endosperm where it was metabolized and used in synthesis of sucrose and methanol-chloroform-water insolubles. Accumulation of [ 14 C]sucrose from supplied [ 14 C]glucosyl-FS indicated that the glucose moiety from the breakdown of sucrose (here FS), which normally occurs in the process of starch synthesis in maize endosperm, was available to the pool of substrates for resynthesis of sucrose. Uptake of FS into maize endosperm without hydrolysis suggest that despite the presence of invertase in maternal tissues and the hydrolysis of a large percentage of sucrose unloaded form the phloem, hexoses are not specifically needed for uptake into maize endosperm

  8. Building blocks for the solution phase synthesis of oligonucleotides: regioselective hydrolysis of 3',5'-Di-O-levulinylnucleosides using an enzymatic approach.

    Science.gov (United States)

    García, Javier; Fernández, Susana; Ferrero, Miguel; Sanghvi, Yogesh S; Gotor, Vicente

    2002-06-28

    A short and convenient synthesis of 3'- and 5'-O-levulinyl-2'-deoxynucleosides has been developed from the corresponding 3',5'-di-O-levulinyl derivatives by regioselective enzymatic hydrolysis, avoiding several tedious chemical protection/deprotection steps. Thus, Candida antartica lipase B (CAL-B) was found to selectively hydrolyze the 5'-levulinate esters, furnishing 3'-O-levulinyl-2'-deoxynucleosides 3 in >80% isolated yields. On the other hand, immobilized Pseudomonas cepacia lipase (PSL-C) and Candida antarctica lipase A (CAL-A) exhibit the opposite selectivity toward the hydrolysis at the 3'-position, affording 5'-O-levulinyl derivatives 4 in >70% yields. A similar hydrolysis procedure was successfully extended to the synthesis of 3'- and 5'-O-levulinyl-protected 2'-O-alkylribonucleosides 7 and 8. This work demonstrates for the first time application of commercial CAL-B and PSL-C toward regioselective hydrolysis of levulinyl esters with excellent selectivity and yields. It is noteworthy that protected cytidine and adenosine base derivatives were not adequate substrates for the enzymatic hydrolysis with CAL-B, whereas PSL-C was able to accommodate protected bases during selective hydrolysis. In addition, we report an improved synthesis of dilevulinyl esters using a polymer-bound carbodiimide as a replacement for dicyclohexylcarbodiimide (DCC), thus considerably simplifying the workup for esterification reactions.

  9. Exploration of process parameters for continuous hydrolysis of canola oil, camelina oil and algal oil

    KAUST Repository

    Wang, Weicheng

    2012-07-01

    Thermal hydrolysis of triglycerides to form free fatty acid (FFA) is a well-established industry practice. Recently, this process has been employed as a first step in the production of biofuels from lipids. To that end, batch and continuous hydrolysis of various feedstocks has been examined at the laboratory scale. Canola, the primary feedstock in this paper, camelina and algal oils were converted to high quality FFA. For the different reaction temperatures, the continuous hydrolysis system was found to provide better yields than the laboratory batch system. In addition, CFD simulation with ANSYS-CFX was used to model the performance and reactant/product separation in the continuous, counter-flow reactor. The effects of reaction temperature, water-to-oil ratio (ratio of water and oil volumetric inflow rate), and preheating of the reactants were examined experimentally. Optimization of these parameters has resulted in an improved, continuous process with high mass yields (89-93%, for reactor temperature of 260°C and water-to-oil ratio of 4:1) and energy efficiency (76%, for reactor temperature of 250°C and water-to-oil ratio of 2:1). Based on the product quality and energy efficiency considerations, the reactor temperature of 260°C and water-to-oil ratio of 4:1 have provided the optimal condition for the lab scale continuous hydrolysis reaction. © 2012 Elsevier B.V.

  10. Exploration of process parameters for continuous hydrolysis of canola oil, camelina oil and algal oil

    KAUST Repository

    Wang, Weicheng; Turner, Timothy L.; Stikeleather, Larry F.; Roberts, William L.

    2012-01-01

    Thermal hydrolysis of triglycerides to form free fatty acid (FFA) is a well-established industry practice. Recently, this process has been employed as a first step in the production of biofuels from lipids. To that end, batch and continuous hydrolysis of various feedstocks has been examined at the laboratory scale. Canola, the primary feedstock in this paper, camelina and algal oils were converted to high quality FFA. For the different reaction temperatures, the continuous hydrolysis system was found to provide better yields than the laboratory batch system. In addition, CFD simulation with ANSYS-CFX was used to model the performance and reactant/product separation in the continuous, counter-flow reactor. The effects of reaction temperature, water-to-oil ratio (ratio of water and oil volumetric inflow rate), and preheating of the reactants were examined experimentally. Optimization of these parameters has resulted in an improved, continuous process with high mass yields (89-93%, for reactor temperature of 260°C and water-to-oil ratio of 4:1) and energy efficiency (76%, for reactor temperature of 250°C and water-to-oil ratio of 2:1). Based on the product quality and energy efficiency considerations, the reactor temperature of 260°C and water-to-oil ratio of 4:1 have provided the optimal condition for the lab scale continuous hydrolysis reaction. © 2012 Elsevier B.V.

  11. Numerical Simulations of Urea Hydrolysis and Calcite Precipitation in Porous Media Using STOMP

    International Nuclear Information System (INIS)

    Guo, Luanjing; Huang, Hai; Hu, Bill X.

    2010-01-01

    Subsurface radionuclide and trace metal contaminants throughout the U.S. Department of Energy (DOE) complex pose one of DOE's greatest challenges for long-term stewardship. One promising in situ immobilization approach of these contaminants is engineered mineral (co)precipitation of calcite driven by urea hydrolysis that is catalyzed by enzyme urease. The tight nonlinear coupling among flow, transport, reaction and reaction-induced property changes of media of this approach was studied by reactive transport simulations with systematically increasing level of complexities of reaction network and physical/chemical heterogeneities using a numerical simulator named STOMP. Sensitivity studies on the reaction rates of both urea hydrolysis and calcite precipitation are performed via controlling urease enzyme concentration and precipitation rate constant according to the rate models employed. We have found that the rate of ureolysis is a dominating factor in the amount of precipitated mineral; however, the spatial distribution of the precipitates depends on both rates of ureolysis and calcite precipitation. A maximum 5% reduction in the porosity was observed within the simulation time period of 6 pore volumes in our 1-dimensional (1D) column simulations. When a low permeability inclusion is considered in the 2D simulations, the altered flow fields redistribute mineral forming constituents, leading to a distorted precipitation reaction front. The simulations also indicate that mineral precipitation occurs along the boundary of the low permeability zone, which implies that contaminants in the low permeability zone could be encapsulated and isolated from the flow paths.

  12. Electrospray ionization mass spectrometry for the hydrolysis complexes of cisplatin: implications for the hydrolysis process of platinum complexes.

    Science.gov (United States)

    Feifan, Xie; Pieter, Colin; Jan, Van Bocxlaer

    2017-07-01

    Non-enzyme-dependent hydrolysis of the drug cisplatin is important for its mode of action and toxicity. However, up until today, the hydrolysis process of cisplatin is still not completely understood. In the present study, the hydrolysis of cisplatin in an aqueous solution was systematically investigated by using electrospray ionization mass spectrometry coupled to liquid chromatography. A variety of previously unreported hydrolysis complexes corresponding to monomeric, dimeric and trimeric species were detected and identified. The characteristics of the Pt-containing complexes were investigated by using collision-induced dissociation (CID). The hydrolysis complexes demonstrate distinctive and correlative CID characteristics, which provides tools for an informative identification. The most frequently observed dissociation mechanism was sequential loss of NH 3 , H 2 O and HCl. Loss of the Pt atom was observed as the final step during the CID process. The formation mechanisms of the observed complexes were explored and experimentally examined. The strongly bound dimeric species, which existed in solution, are assumed to be formed from the clustering of the parent compound and its monohydrated or dihydrated complexes. The role of the electrospray process in the formation of some of the observed ions was also evaluated, and the electrospray ionization-related cold clusters were identified. The previously reported hydrolysis equilibria were tested and subsequently refined via a hydrolysis study resulting in a renewed mechanistic equilibrium system of cisplatin as proposed from our results. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  13. Hydrolytic gain during hydrolysis reactions : implications and correction procedures

    NARCIS (Netherlands)

    Marchal, L.M.; Tramper, J.

    1999-01-01

    Some of the structural parameters of starch (e.g. % beta- or gluco-hydrolysis) were influenced by the increase in mass during the hydrolysis reactions (hydrolytic gain). Procedures were derived to correct this apparent % of hydrolysis to actual % of hydrolysis. These analytically derived equations

  14. Preparation of biodiesel from waste cooking oil via two-step catalyzed process

    International Nuclear Information System (INIS)

    Wang Yong; Liu Pengzhan; Ou Shiyi; Zhang Zhisen

    2007-01-01

    Waste cooking oils (WCO), which contain large amounts of free fatty acids produced in restaurants, are collected by the environmental protection agency in the main cities of China and should be disposed in a suitable way. In this research, a two step catalyzed process was adopted to prepare biodiesel from waste cooking oil whose acid value was 75.92 ± 0.036 mgKOH/g. The free fatty acids of WCO were esterified with methanol catalyzed by ferric sulfate in the first step, and the triglycerides (TGs) in WCO were transesterified with methanol catalyzed by potassium hydroxide in the second step. The results showed that ferric sulfate had high activity to catalyze the esterification of free fatty acids (FFA) with methanol, The conversion rate of FFA reached 97.22% when 2 wt% of ferric sulfate was added to the reaction system containing methanol to TG in10:1 (mole ratio) composition and reacted at 95 deg. C for 4 h. The methanol was vacuum evaporated, and transesterification of the remained triglycerides was performed at 65 deg. C for 1 h in a reaction system containing 1 wt% of potassium hydroxide and 6:1 mole ratio of methanol to TG. The final product with 97.02% of biodiesel, obtained after the two step catalyzed process, was analyzed by gas chromatography. This new process has many advantages compared with the old processes, such as no acidic waste water, high efficiency, low equipment cost and easy recovery of the catalyst

  15. Human myeloperoxidase (MPO) and horseradish peroxidase (HRP) catalyzed oxidation of phenol

    International Nuclear Information System (INIS)

    Ross, D.; Eastmond, D.A.; Ruzo, L.O.; Smith, M.T.

    1986-01-01

    MPO-catalyzed conversion of phenolic metabolites of benzene may be involved in benzene-induced myelotoxicity. The authors have studied the metabolism and protein binding of phenol - the major metabolite of benzene - during peroxidatic oxidation. The major metabolite observed during MPO- and HRP- catalyzed oxidation was characterized as 4,4 biphenol using HPLC and combined GC-MS. When glutathione (GSH) was added to the incubation mixtures, two additional compounds were observed during HPLC analysis which were characterized as GSH-conjugates of 4,4-diphenoquinone by fast atom bombardment MS and by NMR. ESR spectroscopy showed that both MPO-and HRP-catalyzed oxidation of phenol proceeded via the generation of free radical intermediates. Using 14 C-phenol, both MPO- and HRP-catalyzed oxidations resulted in the production of species which bound covalently to boiled liver microsomal protein. The increase in binding correlated well with removal of substrate. Thus, peroxidatic oxidation of phenolic metabolites of benzene in the bone marrow may be involved in benzene-induced myelotoxicity

  16. Zn(OTf)2 catalyzed indolylation and pyrrolylation of isatins: Efficient ...

    Indian Academy of Sciences (India)

    praveenithya

    Zn(OTf)2 catalyzed indolylation and pyrrolylation of isatins: Efficient synthesis and biochemical assay of 3,3- di(heteroaryl)oxindoles. C PRAVEEN a. , S NARENDIRAN b. , P DHEENKUMAR a,c and P T PERUMAL a,. * a. Organic Chemistry Division, Central Leather Research Institute (CSIR), Adyar, Chennai. 600020 ...

  17. DWPF integrated cold runs revised technical bases for precipitate hydrolysis

    International Nuclear Information System (INIS)

    Landon, L.F.

    1992-01-01

    The report defines new precipitate hydrolysis process operating parameters for DWPF Chemical runs assuming the precipitate feed simulants to be processed reflect the decision to implement a final wash of the tetraphenylborate slurry before transfer to DWPF (i.e. the Late Wash Facility). Control of the nitrite content of the tetraphenylborate slurry to 0.01M or less has eliminated the need for hydroxylamine nitrate (HAN) during hydrolysis. Consequently, the oxidant nitrous oxide will not be generated. However, nitric oxide (NO) is expected to be generated (reaction of formic acid with nitrite) and some fraction of the NO can be expected to be oxidized to nitrogen dioxide. The rate of NO generation with low nitrite feed has not been quantified at this time nor is the extent to which the NO is oxidized to NO 2 known. A mass spectrometer is being installed in the Precipitate Hydrolysis Experimental Facility (PHEF) which will enable the NO generation rate to be defined as well as the extent to which the NO is oxidized to NO 2 . There is some undocumented data available for C 6 H 6 /NO and C 6 H 6 /NO 2 with N 2 as the diluent but no similar data for CO 2 . Development of test data in the required time frame is not possible. However, MOC's will be estimated for benzene/NO/NO 2 /CO 2 gas mixtures (the MOC is expected to be approximately 60% less than for the HAN process). Once these data are obtained, and NO/NO 2 concentration profiles are obtained from PHEF hydrolysis process demonstrations, a flammability control strategy for the DWPF Salt Processing Cell will be developed. Implementation of the HAN process purge strategy upon startup of the SPC with the late wash process would be conservative

  18. [Structural characterization of Astragalus polysaccharides using partial acid hydrolysis-hydrophilic interaction liquid chromatography-mass spectrometry].

    Science.gov (United States)

    Liang, Tu; Fu, Qing; Xin, Huaxia; Li, Fangbing; Jin, Yu; Liang, Xinmiao

    2014-12-01

    Water-soluble polysaccharides from traditional Chinese medicine (TCM) have properties of broad-spectrum treatment and low toxicity, making them as important components in natural medicines and health products. In order to solve the problem of polysaccharides characterization caused by their complex structures, a "bottom-up" approach was developed to complete the characterization of polysaccharides from Astragalus. Firstly, Astragalus pieces were extracted with hot water and then were precipitated by ethanol to obtain Astragalus polysaccharides. Secondly, a partial acid hydrolysis method was carried out and the effects of time, acid concentration and temperature on hydrolysis were investigated. The degree of hydrolysis increased along with the increase of hydrolysis time and acid concentration. The temperature played a great role in the hydrolysis process. No hydrolysis of the polysaccharides occurred at low temperature, while the polysaccharides were almost hydrolyzed to monosaccharide at high temperature. Under the optimum hydrolysis conditions (4 h, 1.5 mol/L trifluoroacetic acid, and 80 °C), Astragalus polysaccharides were hydrolyzed to characteristic oligosaccharide fragments. At last, a hydrophilic liquid chromatography-mass spectrometry method was used for the separation and structural characterization of the polysaccharide hydrolysates. The results showed that the resulting polysaccharides were mainly 1--> 4 linear glucan, and gluco-oligosaccharides with the degrees of polymerization (DP) of 4 - 11 were obtained after partial acid hydrolysis. The significance of this study is that it is the guidance for the characterization of other TCM polysaccharides.

  19. Transition Metal Catalyzed Synthesis of Carboxylic Acids, Imines, and Biaryls

    DEFF Research Database (Denmark)

    Santilli, Carola; Madsen, Robert

    the carboxylate.  Manganese catalyzed radical Kumada-type reaction between aryl halidesand aryl Grignard reagents. The reaction between aryl halides and aryl Grignard reagents catalyzed by MnCl2 has been extended to several methyl-substituted aryl iodide reagents byperforming the reaction at 120 ˚C in a microwave...... oven (Scheme ii). A limitation of the heterocoupling process is the concomitant dehalogenation of the aryl halide and homocoupling of the Grignard reagent leading low to moderate yields of the desired heterocoupling product. The mechanism of the cross-coupling process was investigated by performing two...

  20. Production of value added materials by subcritical water hydrolysis ...

    African Journals Online (AJOL)

    The hydrolysis efficiencies of glycine, arginine, and leucine were found to be increased with increasing water temperature, consistent with higher solubility at higher temperatures. The highest yield of amino acids in de-oiled krill hydrolysate was at 280°C. While, the highest amino acid yield in raw krill hydrolysate was at low ...

  1. Syndecans reside in sphingomyelin-enriched low-density fractions of the plasma membrane isolated from a parathyroid cell line.

    Directory of Open Access Journals (Sweden)

    Katarzyna A Podyma-Inoue

    Full Text Available BACKGROUND: Heparan sulfate proteoglycans (HSPGs are one of the basic constituents of plasma membranes. Specific molecular interactions between HSPGs and a number of extracellular ligands have been reported. Mechanisms involved in controlling the localization and abundance of HSPG on specific domains on the cell surface, such as membrane rafts, could play important regulatory roles in signal transduction. METHODOLOGY/PRINCIPAL FINDINGS: Using metabolic radiolabeling and sucrose-density gradient ultracentrifugation techniques, we identified [(35S]sulfate-labeled macromolecules associated with detergent-resistant membranes (DRMs isolated from a rat parathyroid cell line. DRM fractions showed high specific radioactivity ([(35S]sulfate/mg protein, implying the specific recruitment of HSPGs to the membrane rafts. Identity of DRM-associated [(35S]sulfate-labeled molecules as HSPGs was confirmed by Western blotting with antibodies that recognize heparan sulfate (HS-derived epitope. Analyses of core proteins by SDS-PAGE revealed bands with an apparent MW of syndecan-4 (30-33 kDa and syndecan-1 (70 kDa suggesting the presence of rafts with various HSPG species. DRM fractions enriched with HSPGs were characterized by high sphingomyelin content and found to only partially overlap with the fractions enriched in ganglioside GM1. HSPGs could be also detected in DRMs even after prior treatment of cells with heparitinase. CONCLUSIONS/SIGNIFICANCE: Both syndecan-1 and syndecan-4 have been found to specifically associate with membrane rafts and their association seemed independent of intact HS chains. Membrane rafts in which HSPGs reside were also enriched with sphingomyelin, suggesting their possible involvement in FGF signaling. Further studies, involving proteomic characterization of membrane domains containing HSPGs might improve our knowledge on the nature of HSPG-ligand interactions and their role in different signaling platforms.

  2. Peptide models of protein metastable binding sites: competitive kinetics of isomerization and hydrolysis.

    Science.gov (United States)

    Khan, S A; Sekulski, J M; Erickson, B W

    1986-09-09

    alpha 2-Macroglobulin and the complement components C3 and C4 each contain a metastable binding site that is essential for covalent attachment. Two cyclic peptides are useful models of these unusual protein sites. Five-membered lactam 1 (CH3CO-Gly-Cys-Gly-Glu-Glp-Asn-NH2) contains an internal residue of pyroglutamic acid (Glp). Fifteen-membered thiolactone 2 (CH3CO-Gly-Cys-Gly-Glu-Glu-Asn-NH2 15-thiolactone) contains a thiol ester bond between Cys-2 and Glu-5. These isomeric hexapeptides are spontaneously interconverted in water. Competing with the two isomerization reactions are three reactions involving hydrolysis of 1 and 2. These five processes were found to occur simultaneously under physiologic conditions (phosphate-buffered saline, pH 7.3, 37 degrees C). Best estimates of the five rate constants for these apparent first-order reactions were obtained by comparing the observed molar percentages of peptides 1-4 with those calculated from a set of exponential equations. Both isomerization reactions (ring expansion of 1 to 2, k1 = 6.4 X 10(-5) s-1; ring contraction of 2 to 1, k-1 = 69 X 10(-5) s-1) proceeded faster than any of the hydrolysis reactions: alpha-cleavage of 1 with fragmentation to form dipeptide 3 (k2 = 3.3 X 10(-5) s-1), gamma-cleavage of 1 with ring opening to yield mercapto acid 4 (k3 = 0.35 X 10(-5) s-1), and hydrolysis of 2 with ring opening to give 4 (k4 = 1.9 X 10(-5) s-1). The isomerization rate ratio (k1/k-1 = 10.9) agreed with the isomer ratio at equilibrium (1:2 = 11 starting from 1 and 10 starting from 2). The alpha/gamma regioselectivity ratio (k2/k3 = 9.7) for hydrolysis of the internal Glp residue of 1 was consistent with results for model tripeptides. Part of the chemistry of the protein metastable binding sites can be explained by similar isomerization and hydrolysis reactions.

  3. The Deceptively Simple Thermolysis of Trivalent Permethyltitanocene Derivatives (η5-C5Me5)2TiR. Formation of a Tetramethylfulvene Titanium Compound (η6-C5Me4CH2)(η5-C5Me5)Ti and RH, Catalyzed by Permethyltitanocene Hydride, (η5-C5Me5)2TiH

    NARCIS (Netherlands)

    Luinstra, Gerrit A.; Teuben, Jan H.

    1992-01-01

    The complexes Cp*2TiR (Cp* = η5-C5Me5; R = Me, Et, n-Pr, C2H3, CH2CMe3, Ph) undergo thermolysis to yield the fulvene complex Cp*FvTi (Fv = η6-C5Me4CH2) and RH. Kinetic measurements and deuterium labeling studies show that the decomposition is catalyzed by Cp*2TiH, which is formed either by

  4. Effect of Varying Acid Hydrolysis Condition in Gracilaria Sp. Fermentation Using Sasad

    Science.gov (United States)

    Mansuit, H.; Samsuri, M. D. C.; Sipaut, C. S.; Yee, C. F.; Yasir, S. M.; Mansa, R.

    2015-04-01

    Macroalgae or seaweed is being considered as promising feedstock for bioalcohol production due to high polysaccharides content. Polysaccharides can be converted into fermentable sugar through acid hydrolysis pre-treatment. In this study, the potential of using carbohydrate-rich macroalgae, Gracilaria sp. as feedstock for bioalcohol production via various acid hydrolysis conditions prior to the fermentation process was investigated and evaluated. The seaweed used in this research was from the red algae group, using species of Gracilaria sp. which was collected from Sg. Petani Kedah, Malaysia. Pre-treatment of substrate was done using H2SO4 and HCl with molarity ranging from 0.2M to 0.8M. The pretreatment time were varied in the range of 15 to 30 minutes. Fermentation was conducted using Sasad, a local Sabahan fermentation agent as a starter culture. Alcohol extraction was done using a distillation unit. Reducing sugar analysis was done by Benedict test method. Alcohol content analysis was done using specific gravity test. After hydrolysis, it was found out that acid hydrolysis at 0.2M H2SO4 and pre-treated for 20 minutes at 121°C has shown the highest reducing sugar content which has yield (10.06 mg/g) of reducing sugar. It was followed by other samples hydrolysis using 0.4M HCl with 30 minutes pre-treatment and 0.2M H2SO4, 15 minutes pre-treatment with yield of 8.06 mg/g and 5.75 mg/g reducing sugar content respectively. In conclusion, acid hydrolysis of Gracilaria sp. can produce higher reducing sugar yield and thus it can further enhance the bioalcohol production yield. Hence, acid hydrolysis of Gracilaria sp. should be studied more as it is an important step in the bioalcohol production and upscaling process.

  5. The mechanism of transition-metal (Cu or Pd)-catalyzed synthesis of benzimidazoles from amidines: theoretical investigation.

    Science.gov (United States)

    Li, Juan; Gu, Honghong; Wu, Caihong; Du, Lijuan

    2014-11-28

    In this study, the Cu(OAc)2- and [PdCl2(PhCN)2]-catalyzed syntheses of benzimidazoles from amidines were theoretically investigated using density functional theory calculations. For the Cu-catalyzed system, our calculations supported a four-step-pathway involving C-H activation of an arene with Cu(II) via concerted metalation-deprotonation (CMD), followed by oxidation of the Cu(II) intermediate and deprotonation of the imino group by Cu(III), and finally reductive elimination from Cu(III). In our calculations, the barriers for the CMD step and the oxidation step are the same. The results are different from the ones reported by Fu et al. in which the whole reaction mechanism includes three steps and the CMD step is rate determining. On the basis of the calculation results for the [PdCl2(PhCN)2]-catalyzed system, C-H bond breaking by CMD occurs first, followed by the rate-determining C-N bond formation and N-H deprotonation. Pd(III) species is not involved in the [PdCl2(PhCN)2]-catalyzed syntheses of benzimidazoles from amidines.

  6. Towards integrated biorefinery from dried distillers grains: Selective extraction of pentoses using dilute acid hydrolysis

    International Nuclear Information System (INIS)

    Fonseca, Dania A.; Lupitskyy, Robert; Timmons, David; Gupta, Mayank; Satyavolu, Jagannadh

    2014-01-01

    The abundant availability and high level of hemicellulose content make dried distillers grains (DDG) an attractive feedstock for production of pentoses (C5) and conversion of C5 to bioproducts. One target of this work was to produce a C5 extract (hydrolyzate) with high yield and purity with a low concentration of C5 degradation products. A high selectivity towards pentoses was achieved using dilute acid hydrolysis of DDG in a percolation reactor with liquid recirculation. Pretreatment of starting material using screening and ultrasonication resulted in fractional increase of the pentose yield by 42%. A 94% yield of pentoses on the DDG (280.9 g kg −1 ) was obtained. Selective extraction of individual pentoses has been achieved by using a 2-stage hydrolysis process, resulting in arabinose-rich (arabinose 81.5%) and xylose-rich (xylose 85.2%) streams. A broader impact of this work is towards an Integrated Bio-Refinery based on DDG – for production of biofuels, biochemical intermediates, and other bioproducts. - Highlights: • A process for selective extraction of pentoses from DDG was presented as a part of integrated biorefinery approach. • The selectivity for pentoses was high using dilute acid hydrolysis in a percolation reactor with liquid recirculation. • Pretreatment of DDG using screening and ultrasonication resulted in fractional increase of the pentose yield by 42 %. • A 94% yield in pentoses (280.9 g kg −1 of DDG) was obtained. • A 2-stage hydrolysis process, developed to extract individual pentoses, resulted in arabinose and xylose rich streams

  7. Acid-base catalysis of N-[(morpholine)methylene]daunorubicin.

    Science.gov (United States)

    Krause, Anna; Jelińska, Anna; Cielecka-Piontek, Judyta; Klawitter, Maria; Zalewski, Przemysław; Oszczapowicz, Irena; Wąsowska, Małgorzata

    2012-08-01

    The stability of N-[(morpholine)methylene]-daunorubicin hydrochloride (MMD) was investigated in the pH range 0.44-13.54, at 313, 308, 303 and 298 K. The degradation of MMD as a result of hydrolysis is a pseudo-first-order reaction described by the following equation: ln c = ln c(0) - k(obs)• t. In the solutions of hydrochloric acid, sodium hydroxide, borate, acetate and phosphate buffers, k(obs) = k(pH) because general acid-base catalysis was not observed. Specific acid-base catalysis of MMD comprises the following reactions: hydrolysis of the protonated molecules of MMD catalyzed by hydrogen ions (k(1)) and spontaneous hydrolysis of MMD molecules other than the protonated ones (k(2)) under the influence of water. The total rate of the reaction is equal to the sum of partial reactions: k(pH) = k(1) • a(H)+ • f(1) + k(2) • f(2) where: k(1) is the second-order rate constant (mol(-1) l s(-1)) of the specific hydrogen ion-catalyzed degradation of the protonated molecules of MMD; k(2) is the pseudo-first-order rate constant (s(-1)) of the water-catalyzed degradation of MMD molecules other than the protonated ones, f(1) - f(2) are fractions of the compound. MMD is the most stable at approx. pH 2.5.

  8. Twisted Amides: From Obscurity to Broadly Useful Transition-Metal-Catalyzed Reactions by N-C Amide Bond Activation.

    Science.gov (United States)

    Liu, Chengwei; Szostak, Michal

    2017-05-29

    The concept of using amide bond distortion to modulate amidic resonance has been known for more than 75 years. Two classic twisted amides (bridged lactams) ingeniously designed and synthesized by Kirby and Stoltz to feature fully perpendicular amide bonds, and as a consequence emanate amino-ketone-like reactivity, are now routinely recognized in all organic chemistry textbooks. However, only recently the use of amide bond twist (distortion) has advanced to the general organic chemistry mainstream enabling a host of highly attractive N-C amide bond cross-coupling reactions of broad synthetic relevance. In this Minireview, we discuss recent progress in this area and present a detailed overview of the prominent role of amide bond destabilization as a driving force in the development of transition-metal-catalyzed cross-coupling reactions by N-C bond activation. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Preparation of Rh/Ag bimetallic nanoparticles as effective catalyst for hydrogen generation from hydrolysis of KBH4

    Science.gov (United States)

    Huang, Liang; Jiao, Chengpeng; Wang, Liqiong; Huang, Zili; Liang, Feng; Liu, Simin; Wang, Yuhua; Zhang, Haijun; Zhang, Shaowei

    2018-01-01

    ISOBAM-104 protected Rh/Ag bimetallic nanoparticles (NPs) with average diameter less than 3.0 nm were synthesized by a co-reduction method. Ultraviolet-visible spectroscopy, transmission electron microscopy (TEM), high-resolution TEM and x-ray photoelectron spectroscopy (XPS) were employed to characterize the structure, particle size, and electronic structure of the prepared bimetallic NPs. The catalytic activities of prepared bimetallic NPs for hydrogen generation from hydrolysis of a basic KBH4 solution were evaluated in detail. The results indicated that as-prepared Rh/Ag bimetallic NPs showed a higher catalytic activity than corresponding monometallic NPs. Among all the monometallic NPs and bimetallic NPs, Rh80Ag20 bimetallic NPs exhibited the highest catalytic activity with a value of 6010 mol-H2·h-1·mol-catalyst-1 at pH = 12 and 303 K. The high catalytic activities of Rh/Ag bimetallic NPs could be attributed to presence of negatively charged Rh atoms and positively charged Ag atoms, which is supported by the results of XPS and density functional theory calculation. Based on the kinetic study, the apparent activation energy for the hydrolysis reaction of the basic KBH4 solution catalyzed by Rh80Ag20 bimetallic NPs was about 47.0 ± 3.9 kJ mol-1.

  10. [Response surface method optimize of nano-silica solid dispersion technology assistant enzymatic hydrolysis preparation genistein].

    Science.gov (United States)

    Jin, Xin; Zhang, Zhen-Hai; Zhu, Jing; Sun, E; Yu, Dan-Hong; Chen, Xiao-Yun; Liu, Qi-Yuan; Ning, Qing; Jia, Xiao-Bin

    2012-04-01

    This article reports that nano-silica solid dispersion technology was used to raise genistein efficiency through increasing the enzymatic hydrolysis rate. Firstly, genistin-nano-silica solid dispersion was prepared by solvent method. And differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) were used to verify the formation of solid dispersion, then enzymatic hydrolysis of solid dispersion was done by snailase to get genistein. With the conversion of genistein as criteria, single factor experiments were used to study the different factors affecting enzymatic hydrolysis of genistin and its solid dispersion. And then, response surface method was used to optimize of nano-silica solid dispersion technology assistant enzymatic hydrolysis. The optimum condition to get genistein through enzymatic hydrolysis of genistin-nano-silica solid dispersion was pH 7.1, temperature 52.2 degrees C, enzyme concentration 5.0 mg x mL(-1) and reaction time 7 h. Under this condition, the conversion of genistein was (93.47 +/- 2.40)%. Comparing with that without forming the genistin-nano-silica solid dispersion, the conversion increased 2.62 fold. At the same time, the product of hydrolysis was purified to get pure genistein. The method of enzymatic hydrolysis of genistin-nano-silica solid dispersion by snailase to obtain genistein is simple, efficiency and suitable for the modern scale production.

  11. Rhodium(iii)-catalyzed ortho-olefination of aryl phosphonates.

    Science.gov (United States)

    Chary, Bathoju Chandra; Kim, Sunggak

    2013-09-25

    Rhodium(iii)-catalyzed C-H olefination of aryl phosphonic esters is reported for the first time. In this mild and efficient process, the phosphonic ester group is utilized successfully as a new directing group. In addition, mono-olefination for aryl phosphonates is observed using a phosphonic diamide directing group.

  12. Structural changes in lignin during organosolv pretreatment of Liriodendron tulipifera and the effect on enzymatic hydrolysis

    International Nuclear Information System (INIS)

    Koo, Bon-Wook; Min, Byeong-Cheol; Gwak, Ki-Seob; Lee, Soo-Min; Choi, Joon-Weon; Yeo, Hwanmyeong; Choi, In-Gyu

    2012-01-01

    Although organosolv pretreatment removed substantial amounts of lignin and xylan, the yield of glucan which is a major sugar source for fermentation to ethanol is more than 90% in most conditions of the organosolv pretreatment. Relative lignin contents of all pretreated biomass were more than 200 g kg −1 , however enzymatic conversions were increased dramatically comparing to untreated biomass. Therefore the correlation between lignin and enzymatic hydrolysis could not be explained just by lignin content, and other changes resulting from lignin removal affected enzymatic hydrolysis. Results on enzymatic conversion and sugar recovery suggested that the critical temperature improving enzymatic hydrolysis significantly was between 120 °C and 130 °C. Microscopic analysis using Field emission scanning electron microscopy (FE-SEM) showed that structural lignin changes happened through organosolv pretreatment. Lignins were isolated from lignin carbohydrate complex (LCC) at the initial stage and then migrated to the surface of biomass. The isolated and migrated lignins were finally redistributed onto surface. These structural changes formed droplets on surface and increased pore volume in pretreated biomass. The increase in pore volume also increased available surface area and enzyme adsorption at initial stage, and thus enzymatic conversion increased significantly through organosolv pretreatment. It was verified that the droplets were mainly composed of lignin and the lignin droplets inhibited enzymatic hydrolysis through adsorption with cellulase. -- Highlights: ► Just lignin contents cannot explain a correlation with enzymatic hydrolysis. ► Several changes resulted from lignin removal must affect enzymatic hydrolysis. ► Droplets are formed by structural changes in lignin during organosolv pretreatment. ► Formation of the lignin droplet increases the pore volume in biomass. ► The increase in pore volume enhances the enzymatic hydrolysis.

  13. Co-{alpha}Al{sub 2}O{sub 3}-Cu as shaped catalyst in NaBH{sub 4} hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Chamoun, R. [Universite Lyon 1, CNRS, UMR 5615, Laboratoire des Multimateriaux et Interfaces, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne (France); Universite Libanaise, Faculte des Sciences II, Laboratoire de physique appliquee, 90656 Jdeidet El Metn (Lebanon); Demirci, U.B.; Miele, P. [Universite Lyon 1, CNRS, UMR 5615, Laboratoire des Multimateriaux et Interfaces, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne (France); Zaatar, Y.; Khoury, A. [Universite Libanaise, Faculte des Sciences II, Laboratoire de physique appliquee, 90656 Jdeidet El Metn (Lebanon)

    2010-07-15

    A study about catalytic films of Co-supported-over-{alpha}Al{sub 2}O{sub 3} fabricated by electrophoretic deposition (EPD) is reported, the as-prepared shaped catalysts being intended to catalyze NaBH{sub 4} hydrolysis. Co-{alpha}Al{sub 2}O{sub 3} supported over Cu substrate can be prepared by a 2-step route: (i) preparation of the supported catalyst Co-{alpha}Al{sub 2}O{sub 3} (in powder form) by wet impregnation of CoCl{sub 2} over {alpha}Al{sub 2}O{sub 3}, followed by a reduction, and (ii) fabrication of Co-{alpha}Al{sub 2}O{sub 3}-Cu (thin film over Cu) by EPD. Both types of catalysts, whatever their form, are highly efficient in hydrolyzing NaBH{sub 4}, conversions of 100% and HGRs of tens of mL(H{sub 2}) min{sup -1} being achieved at 60-80 C. The Co-{alpha}Al{sub 2}O{sub 3}-Cu catalysts are even more reactive than the Co-{alpha}Al{sub 2}O{sub 3} catalysts because the surface of the former materials becomes much more acid than that of the latter ones in the course of the EPD process. The respective rate laws and reaction kinetics have been determined. Independently on the catalyst form, apparent activation energies of about 52 kJ mol{sup -1} and positive reaction orders versus the initial NaBH{sub 4} concentration (i.e. 0.3-0.7) were calculated, suggesting that the EPD does not affect the reaction mechanisms. Besides, it is showed that the hydrolysis is really catalytic as well as typical of a heterogeneous process. For example, an apparent reaction order versus the Co content of 0.9 was calculated. All of these results among others are reported and discussed in the present article. (author)

  14. Investigation of the profile and kinetics of degradation of rivaroxaban using HPLC, TLC-densitometry and LC/MS/MS: Application to pre-formulation studies

    Directory of Open Access Journals (Sweden)

    Mohamed A. Abdallah

    2015-06-01

    Full Text Available Rivaroxaban (RIVA, an amide group-containing oral anticoagulant was subjected to stress conditions commonly required for the registration of pharmaceuticals: base and acid-catalyzed hydrolysis (0.1 M, 60 °C, 3–6 h, oxidation (10% H2O2, 24 h, photodegradation (300–800 nm, 24 h and thermal decomposition (50 °C, 6 h. Two major degradation products were separated and identified using TLC and LC/MS/MS, respectively. An orthogonal stability-indicating testing protocol (RP-HPLC and NP-TLC-densitometry was developed and validated according to ICH guidelines. Both assays enabled the determination of RIVA in the presence of its degradation products as well as the kinetics of degradation. Determination was carried out over a concentration range of (5.00–50.00 μg/mL and (0.40–12.00 μg/band with an accuracy of (100.81% ± 1.03 and (100.29% ± 1.08 for HPLC and TLC-densitometry, respectively. Results indicated that RIVA was stable towards oxidation, photodegradation and thermal decomposition but extremely sensitive to hydrolysis. Two major degradation products were detected in the case of base-catalyzed hydrolysis while only one degradation product was detected upon acid-catalyzed hydrolysis. This could be attributed to the presence of amide groups in RIVA structure of different stability profiles. The kinetics of hydrolysis was investigated in more detail and the reaction was found to follow the pseudo first order kinetics, as confirmed by the results of both HPLC and TLC-densitometric assays. The applicability of the assay for the determination of RIVA content and dissolution pattern of the innovator product as well as three generic formulations was demonstrated.

  15. Point mutation in FGF receptor eliminates phosphatidylinositol hydrolysis without affecting mitogenesis.

    Science.gov (United States)

    Mohammadi, M; Dionne, C A; Li, W; Li, N; Spivak, T; Honegger, A M; Jaye, M; Schlessinger, J

    1992-08-20

    Stimulation of growth factor receptors with tyrosine kinase activity is followed by rapid receptor dimerization, tyrosine autophosphorylation and phosphorylation of signalling molecules such as phospholipase C gamma (PLC gamma) and the ras GTPase-activating protein. PLC gamma and GTPase-activating protein bind to specific tyrosine-phosphorylated regions in growth factor receptors through their src-homologous SH2 domains. Growth factor-induced tyrosine phosphorylation of PLC gamma is essential for stimulation of phosphatidylinositol hydrolysis in vitro and in vivo. We have shown that a short phosphorylated peptide containing tyrosine at position 766 from a conserved region of the fibroblast growth factor (FGF) receptor is a binding site for the SH2 domain of PLC gamma (ref. 8). Here we show that an FGF receptor point mutant in which Tyr 766 is replaced by a phenylalanine residue (Y766F) is unable to associate with and tyrosine-phosphorylate PLC gamma or to stimulate hydrolysis of phosphatidylinositol. Nevertheless, the Y766F FGF receptor mutant can be autophosphorylated, and can phosphorylate several cellular proteins and stimulate DNA synthesis. Our data show that phosphorylation of the conserved Tyr 766 of the FGF receptor is essential for phosphorylation of PLC gamma and for hydrolysis of phosphatidylinositol, but that elimination of this hydrolysis does not affect FGF-induced mitogenesis.

  16. Characterization of a unique class C acid phosphatase from Clostridium perfringens.

    Science.gov (United States)

    Reilly, Thomas J; Chance, Deborah L; Calcutt, Michael J; Tanner, John J; Felts, Richard L; Waller, Stephen C; Henzl, Michael T; Mawhinney, Thomas P; Ganjam, Irene K; Fales, William H

    2009-06-01

    Clostridium perfringens is a gram-positive anaerobe and a pathogen of medical importance. The detection of acid phosphatase activity is a powerful diagnostic indicator of the presence of C. perfringens among anaerobic isolates; however, characterization of the enzyme has not previously been reported. Provided here are details of the characterization of a soluble recombinant form of this cell-associated enzyme. The denatured enzyme was approximately 31 kDa and a homodimer in solution. It catalyzed the hydrolysis of several substrates, including para-nitrophenyl phosphate, 4-methylumbelliferyl phosphate, and 3' and 5' nucleoside monophosphates at pH 6. Calculated K(m)s ranged from 0.2 to 0.6 mM with maximum velocity ranging from 0.8 to 1.6 micromol of P(i)/s/mg. Activity was enhanced in the presence of some divalent cations but diminished in the presence of others. Wild-type enzyme was detected in all clinical C. perfringens isolates tested and found to be cell associated. The described enzyme belongs to nonspecific acid phosphatase class C but is devoid of lipid modification commonly attributed to this class.

  17. Production of value added materials by subcritical water hydrolysis ...

    African Journals Online (AJOL)

    use

    2011-12-14

    Dec 14, 2011 ... from raw and de-oiled krill was examined over the temperature range of 200 to 280°C, ratio of material to water for hydrolysis was 1:50 .... stirring. The raw material and SC-CO2 (run 1, 2 and 3) extracted residues were prepared ... amino acid auto analyzer (Hitachi L-8900, Tokyo, Japan). RESULTS AND ...

  18. Kinetic modelling of enzymatic starch hydrolysis

    NARCIS (Netherlands)

    Bednarska, K.A.

    2015-01-01

    Kinetic modelling of enzymatic starch hydrolysis – a summary

    K.A. Bednarska

    The dissertation entitled ‘Kinetic modelling of enzymatic starch hydrolysis’ describes the enzymatic hydrolysis and kinetic modelling of liquefaction and saccharification of wheat starch.

  19. Conversion of rice straw to sugars by dilute-acid hydrolysis

    International Nuclear Information System (INIS)

    Karimi, Keikhosro; Kheradmandinia, Shauker; Taherzadeh, Mohammad J.

    2006-01-01

    Hydrolysis of rice straw by dilute sulfuric acid at high temperature and pressure was investigated in one and two stages. The hydrolyses were carried out in a 10-l reactor, where the hydrolysis retention time (3-10 min), pressure (10-35 bar) and acid concentration (0-1%) were examined. Optimization of first stage hydrolysis is desirable to achieve the highest yield of the sugars from hemicellulose and also as a pretreatment for enzymatic hydrolysis. The results show the ability of first stage hydrolysis to depolymerize xylan to xylose with a maximum yield of 80.8% at hydrolysis pressure of 15 bar, 10 min retention time and 0.5% acid concentration. However, the yield of glucose from glucan was relatively low in first stage hydrolysis at a maximum of 25.8%. The solid residuals were subjected to further dilute-acid hydrolysis in this study. This second-stage hydrolysis without addition of the acid could not increase the yield of glucose from glucan beyond 26.6%. On the other hand, the best results of the hydrolysis were achieved, when 0.5% sulfuric acid was added prior to each stage in two-stage hydrolysis. The best results of the second stage of the hydrolysis were achieved at the hydrolysis pressure and the retention time of 30 bar and 3 min in the second stage hydrolysis, where a total of 78.9% of xylan and 46.6% of glucan were converted to xylose and glucose, respectively in the two stages. Formation of furfural and HMF were functions of the hydrolysis pressure, acid concentration, and retention time, whereas the concentration of acetic acid was almost constant at pressure of higher than 10 bar and a total retention time of 10 min

  20. Enzymatic hydrolysis of plant extracts containing inulin

    Energy Technology Data Exchange (ETDEWEB)

    Guiraud, J.P.; Galzy, P.

    1981-10-01

    Inulin-rich extracts of chicory and Jerusalem artichoke are a good potential source of fructose. Total enzymatic hydrolysis of these extracts can be effected by yeast inulinases (EC 3.2.1.7). Chemical prehydrolysis is unfavourable. Enzymatic hydrolysis has advantages over chemical hydrolysis: it does not produce a dark-coloured fraction or secondary substances. It is possible to envisage the preparation of high fructose syrups using this process. (Refs. 42).

  1. Plasma membrane associated phospholipase C from human platelets: Synergistic stimulation of phosphatidylinositol 4,5-bisphosphate hydrolysis by thrombin and guanosine 5'-O-(3-thiotriphosphate)

    International Nuclear Information System (INIS)

    Baldassare, J.J.; Henderson, P.A.; Fisher, G.J.

    1989-01-01

    The effects of thrombin and GTPγS on the hydrolysis of phosphoinositides by membrane-associated phospholipase C (PLC) from human platelets were examined with endogenous [ 3 H]inositol-labeled membranes or with lipid vesicles containing either [ 3 H]phosphatidylinositol or [ 3 H]phosphatidylinositol 4,5-bisphosphate. GTPγS (1 μM) or thrombin (1 unit/mL) did not stimulate release of inositol trisphosphate (IP 3 ), inositol bisphosphate (IP 2 ), or inositol phosphate (IP) from [ 3 H]inositol-labeled membranes. IP 2 and IP 3 , but not IP, from [ 3 H]inositol-labeled membranes were, however, stimulated 3-fold by GTPγS (1 μM) plus thrombin (1 unit/mL). A higher concentration of GTPγS (100 μM) alone also stimulated IP 2 and IP 3 , but not IP, release. In the presence of 1 mM calcium, release of IP 2 and IP 3 was increased 6-fold over basal levels; however, formation of IP was not observed. At submicromolar calcium concentration, hydrolysis of exogenous phosphatidylinositol 4,5-bisphosphate (PIP 2 ) by platelet membrane associated PLC was also markedly enhanced by GTPγS (100 μM) or GTPγS (1 μM) plus thrombin (1 unit/mL). Under identical conditions, exogenous phosphatidylinositol (PI) was not hydrolyzed. The same substrate specificity was observed when the membrane-associated PLC was activated with 1 mM calcium. Thrombin-induced hydrolysis of PIP 2 was inhibited by treatment of the membranes with pertussis toxin or pretreatment of intact platelets with 12-O-tetradecanoyl-13-acetate (TPA) prior to preparation of membranes. Pertussis toxin did not inhibit GTPγS (100 μM) or calcium (1 mM) dependent PIP 2 breakdown, while TPA inhibited GTPγS-dependent but not calcium-dependent phospholipase C activity

  2. Enantioselective copper-catalyzed carboetherification of unactivated alkenes.

    Science.gov (United States)

    Bovino, Michael T; Liwosz, Timothy W; Kendel, Nicole E; Miller, Yan; Tyminska, Nina; Zurek, Eva; Chemler, Sherry R

    2014-06-16

    Chiral saturated oxygen heterocycles are important components of bioactive compounds. Cyclization of alcohols onto pendant alkenes is a direct route to their synthesis, but few catalytic enantioselective methods enabling cyclization onto unactivated alkenes exist. Herein reported is a highly efficient copper-catalyzed cyclization of γ-unsaturated pentenols which terminates in C-C bond formation, a net alkene carboetherification. Both intra- and intermolecular C-C bond formations are demonstrated, thus yielding functionalized chiral tetrahydrofurans as well as fused-ring and bridged-ring oxabicyclic products. Transition-state calculations support a cis-oxycupration stereochemistry-determining step. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Enzymatic hydrolysis of biomimetic bacterial cellulose-hemicellulose composites.

    Science.gov (United States)

    Penttilä, Paavo A; Imai, Tomoya; Hemming, Jarl; Willför, Stefan; Sugiyama, Junji

    2018-06-15

    The production of biofuels and other chemicals from lignocellulosic biomass is limited by the inefficiency of enzymatic hydrolysis. Here a biomimetic composite material consisting of bacterial cellulose and wood-based hemicelluloses was used to study the effects of hemicelluloses on the enzymatic hydrolysis with a commercial cellulase mixture. Bacterial cellulose synthesized in the presence of hemicelluloses, especially xylan, was found to be more susceptible to enzymatic hydrolysis than hemicellulose-free bacterial cellulose. The reason for the easier hydrolysis could be related to the nanoscale structure of the substrate, particularly the packing of cellulose microfibrils into ribbons or bundles. In addition, small-angle X-ray scattering was used to show that the average nanoscale morphology of bacterial cellulose remained unchanged during the enzymatic hydrolysis. The reported easier enzymatic hydrolysis of bacterial cellulose produced in the presence of wood-based xylan offers new insights to overcome biomass recalcitrance through genetic engineering. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Bisphenol diglycidyl ethers and bisphenol A and their hydrolysis in drinking water.

    Science.gov (United States)

    Lane, R F; Adams, C D; Randtke, S J; Carter, R E

    2015-04-01

    Epoxy coatings are commonly used to protect the interior (and exterior) surfaces of water mains and storage tanks and can be used on the interior surfaces of water pipes in homes, hospitals, hotels, and other buildings. Common major components of epoxies include bisphenols, such as bisphenol A (BPA) or bisphenol F (BPF), and their reactive prepolymers, bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE), respectively. There currently are health concerns about the safety of BPA and BPF due to known estrogenic effects. Determination of key bisphenol leachates, development of a hydrolysis model, and identification of stable hydrolysis products will aid in assessment of human bisphenol exposure through ingestion of drinking water. Liquid chromatography/mass spectrometry (LC/MS/MS) was used for quantitation of key analytes, and a pseudo-first order kinetic approach was used for modeling. In fill-and-dump studies on epoxy-coated pipe specimens, BADGE and a BPA-like compound were identified as leachates. The BADGE hydrolysis model predicts BADGE half-lives at pH 7 and 15, 25, 35, and 40 °C to be 11, 4.6, 2.0, and 1.4 days respectively; the BFDGE half-life was 5 days at pH 7 and 25 °C. The two identified BADGE hydrolysis products are BADGE-H2O and BADGE 2H2O, with BADGE 2H2O being the final end product under the conditions studied. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Effects of hydrolysis on solid-state relaxation and stickiness behavior of sodium caseinate-lactose powders.

    Science.gov (United States)

    Mounsey, J S; Hogan, S A; Murray, B A; O'Callaghan, D J

    2012-05-01

    Hydrolyzed or nonhydrolyzed sodium caseinate-lactose dispersions were spray dried, at a protein: lactose ratio of 0.5, to examine the effects of protein hydrolysis on relaxation behavior and stickiness of model powders. Sodium caseinate (NC) used included a nonhydrolyzed control (DH 0) and 2 hydrolyzed variants (DH 8.3 and DH 15), where DH = degree of hydrolysis (%). Prior to spray drying, apparent viscosities of liquid feeds (at 70°C) at a shear rate of 20/s were 37.6, 3.14, and 3.19 mPa·s, respectively, for DH 0, DH 8, and DH 15 dispersions. Powders containing hydrolyzed casein were more susceptible to sticking than those containing intact NC. The former had also lower bulk densities and powder particle sizes. Scanning electron microscopy showed that hydrolyzed powders had thinner particle walls and were more friable than powders containing intact NC. Secondary structure of caseinates, determined by Fourier transform infrared spectroscopy, was affected by the relative humidity of storage and the presence of lactose as co-solvent rather than its physical state. Glass transition temperatures and lactose crystallization temperatures, determined by differential scanning calorimetry were not affected by caseinate hydrolysis, although the effects of protein hydrolysis on glass-rubber transitions (T(gr)) could be determined by thermo-mechanical analysis. Powders containing hydrolyzed NC had lower T(gr) values (~30°C) following storage at a higher subcrystallization relative humidity (33%) compared with powder with nonhydrolyzed NC (T(gr) value of ~40°C), an effect that reflects more extensive plasticization of powder matrices by moisture. Results support that sodium caseinate-lactose interactions were weak but that relaxation behavior, as determined by the susceptibility of powder to sticking, was affected by hydrolysis of sodium caseinate. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  6. Synthesis of benzimidazoles via iridium-catalyzed acceptorless dehydrogenative coupling.

    Science.gov (United States)

    Sun, Xiang; Lv, Xiao-Hui; Ye, Lin-Miao; Hu, Yu; Chen, Yan-Yan; Zhang, Xue-Jing; Yan, Ming

    2015-07-21

    Iridium-catalyzed acceptorless dehydrogenative coupling of tertiary amines and arylamines has been developed. A number of benzimidazoles were prepared in good yields. An iridium-mediated C-H activation mechanism is suggested. This finding represents a novel strategy for the synthesis of benzimidazoles.

  7. Reaction kinetics of cellulose hydrolysis in subcritical and supercritical water

    Science.gov (United States)

    Olanrewaju, Kazeem Bode

    The uncertainties in the continuous supply of fossil fuels from the crisis-ridden oil-rich region of the world is fast shifting focus on the need to utilize cellulosic biomass and develop more efficient technologies for its conversion to fuels and chemicals. One such technology is the rapid degradation of cellulose in supercritical water without the need for an enzyme or inorganic catalyst such as acid. This project focused on the study of reaction kinetics of cellulose hydrolysis in subcritical and supercritical water. Cellulose reactions at hydrothermal conditions can proceed via the homogeneous route involving dissolution and hydrolysis or the heterogeneous path of surface hydrolysis. The work is divided into three main parts. First, the detailed kinetic analysis of cellulose reactions in micro- and tubular reactors was conducted. Reaction kinetics models were applied, and kinetics parameters at both subcritical and supercritical conditions were evaluated. The second major task was the evaluation of yields of water soluble hydrolysates obtained from the hydrolysis of cellulose and starch in hydrothermal reactors. Lastly, changes in molecular weight distribution due to hydrothermolytic degradation of cellulose were investigated. These changes were also simulated based on different modes of scission, and the pattern generated from simulation was compared with the distribution pattern from experiments. For a better understanding of the reaction kinetics of cellulose in subcritical and supercritical water, a series of reactions was conducted in the microreactor. Hydrolysis of cellulose was performed at subcritical temperatures ranging from 270 to 340 °C (tau = 0.40--0.88 s). For the dissolution of cellulose, the reaction was conducted at supercritical temperatures ranging from 375 to 395 °C (tau = 0.27--0.44 s). The operating pressure for the reactions at both subcritical and supercritical conditions was 5000 psig. The results show that the rate-limiting step in

  8. Chlamydia trachomatis co-opts GBF1 and CERT to acquire host sphingomyelin for distinct roles during intracellular development.

    Directory of Open Access Journals (Sweden)

    Cherilyn A Elwell

    2011-09-01

    Full Text Available The strain designated Chlamydia trachomatis serovar that was used for experiments in this paper is Chlamydia muridarum, a species closely related to C. trachomatis (and formerly termed the Mouse Pneumonitis strain of C. trachomatis. [corrected]. The obligate intracellular pathogen Chlamydia trachomatis replicates within a membrane-bound inclusion that acquires host sphingomyelin (SM, a process that is essential for replication as well as inclusion biogenesis. Previous studies demonstrate that SM is acquired by a Brefeldin A (BFA-sensitive vesicular trafficking pathway, although paradoxically, this pathway is dispensable for bacterial replication. This finding suggests that other lipid transport mechanisms are involved in the acquisition of host SM. In this work, we interrogated the role of specific components of BFA-sensitive and BFA-insensitive lipid trafficking pathways to define their contribution in SM acquisition during infection. We found that C. trachomatis hijacks components of both vesicular and non-vesicular lipid trafficking pathways for SM acquisition but that the SM obtained from these separate pathways is being utilized by the pathogen in different ways. We show that C. trachomatis selectively co-opts only one of the three known BFA targets, GBF1, a regulator of Arf1-dependent vesicular trafficking within the early secretory pathway for vesicle-mediated SM acquisition. The Arf1/GBF1-dependent pathway of SM acquisition is essential for inclusion membrane growth and stability but is not required for bacterial replication. In contrast, we show that C. trachomatis co-opts CERT, a lipid transfer protein that is a key component in non-vesicular ER to trans-Golgi trafficking of ceramide (the precursor for SM, for C. trachomatis replication. We demonstrate that C. trachomatis recruits CERT, its ER binding partner, VAP-A, and SM synthases, SMS1 and SMS2, to the inclusion and propose that these proteins establish an on-site SM biosynthetic

  9. Kinetics of enzymatic hydrolysis of methyl ricinoleate

    OpenAIRE

    Neeharika, T. S.V.R.; Lokesh, P.; Prasanna Rani, K. N.; Prathap Kumar, T.; Prasad, R. B.N.

    2015-01-01

    Ricinoleic acid is an unsaturated hydroxy fatty acid that naturally occurs in castor oil in proportions of up to 85–90%. Ricinoleic acid is a potential raw material and finds several applications in coatings, lubricant formulations and pharmaceutical areas. Enzymatic hydrolysis of castor oil is preferred over conventional hydrolysis for the preparation of ricinoleic acid to avoid estolide formation. A kinetics analysis of the enzymatic hydrolysis of Methyl Ricinoleate in the presence of Candi...

  10. Application of the pM'-pCH diagrams in the determination of hydrolysis constants of the lanthanides

    International Nuclear Information System (INIS)

    Lopez G, H.; Jimenez R, M.; Solache R, M.; Rojas H, A.

    2001-01-01

    The pM ' -pC H diagrams allowed to determine the saturation and non-saturation zones of Lu(OH) 3 in solid phase and those were applied for determining the hydrolysis and lutetium solubility constants, using the radioactive isotope Lu-177. The first constant of hydrolysis was also determined by the potentiometric method in absence of solid phase. (Author)

  11. Biocatalytic production of 3′-sialyllactose by use of a modified sialidase with superior trans-sialidase activity

    DEFF Research Database (Denmark)

    Michalak, Malwina; Larsen, Dorte Møller; Jers, Carsten

    2014-01-01

    ′-sialyllactose production by optimizing pH, temperature, acceptor, and donor concentrations using response surface designs. At the optimum reaction conditions, the Tr6 catalyzed the transfer of sialic acid from cGMP to lactose at high efficiency without substantial hydrolysis of the 3′-sialyllactose product......Casein glycomacropeptide (cGMP) and lactose, which are purified (or semi-purified) components obtained from side streams from dairy industry operations, were used as substrates for enzyme catalyzed production of 3′-sialyllactose, a model case compound for human milk oligosaccharides (HMOs...

  12. Fiber specific changes in sphingolipid metabolism in skeletal muscles of hyperthyroid rats.

    Science.gov (United States)

    Chabowski, A; Zendzian-Piotrowska, M; Mikłosz, A; Łukaszuk, B; Kurek, K; Górski, J

    2013-07-01

    Thyroid hormones (T3, T4) are well known modulators of different cellular signals including the sphingomyelin pathway. However, studies regarding downstream effects of T3 on sphingolipid metabolism in skeletal muscle are scarce. In the present work we sought to investigate the effects of hyperthyroidism on the activity of the key enzymes of ceramide metabolism as well as the content of fundamental sphingolipids. Based on fiber/metabolic differences, we chose three different skeletal muscles, with diverse fiber compositions: soleus (slow-twitch oxidative), red (fast-twitch oxidative-glycolytic) and white (fast-twitch glycolytic) section of gastrocnemius. We demonstrated that T3 induced accumulation of sphinganine, ceramide, sphingosine, as well as sphingomyelin, mostly in soleus and in red, but not white section of gastrocnemius. Concomitantly, the activity of serine palmitoyltransferase and acid/neutral ceramidase was increased in more oxidative muscles. In conclusion, hyperthyroidism induced fiber specific changes in the content of sphingolipids that were relatively more related to de novo synthesis of ceramide rather than to its generation via hydrolysis of sphingomyelin.

  13. Bioethanol production: an integrated process of low substrate loading hydrolysis-high sugars liquid fermentation and solid state fermentation of enzymatic hydrolysis residue.

    Science.gov (United States)

    Chu, Qiulu; Li, Xin; Ma, Bin; Xu, Yong; Ouyang, Jia; Zhu, Junjun; Yu, Shiyuan; Yong, Qiang

    2012-11-01

    An integrated process of enzymatic hydrolysis and fermentation was investigated for high ethanol production. The combination of enzymatic hydrolysis at low substrate loading, liquid fermentation of high sugars concentration and solid state fermentation of enzymatic hydrolysis residue was beneficial for conversion of steam explosion pretreated corn stover to ethanol. The results suggested that low substrate loading hydrolysis caused a high enzymatic hydrolysis yield; the liquid fermentation of about 200g/L glucose by Saccharomyces cerevisiae provided a high ethanol concentration which could significantly decrease cost of the subsequent ethanol distillation. A solid state fermentation of enzymatic hydrolysis residue was combined, which was available to enhance ethanol production and cellulose-to-ethanol conversion. The results of solid state fermentation demonstrated that the solid state fermentation process accompanied by simultaneous saccharification and fermentation. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Automated Quantum Mechanical Predictions of Enantioselectivity in a Rhodium-Catalyzed Asymmetric Hydrogenation.

    Science.gov (United States)

    Guan, Yanfei; Wheeler, Steven E

    2017-07-24

    A computational toolkit (AARON: An automated reaction optimizer for new catalysts) is described that automates the density functional theory (DFT) based screening of chiral ligands for transition-metal-catalyzed reactions with well-defined reaction mechanisms but multiple stereocontrolling transition states. This is demonstrated for the Rh-catalyzed asymmetric hydrogenation of (E)-β-aryl-N-acetyl enamides, for which a new C 2 -symmetric phosphorus ligand is designed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Temperature and base requirements for the alkaline hydrolysis of okadaite's esters.

    Science.gov (United States)

    Rodrigues, Susana M; Vale, Paulo

    2009-06-01

    Portuguese bivalves are recurrently contaminated with okadaic acid (OA) and dinophysistoxin-2 (DTX2), found mainly in esterified forms. Throughout the years different conditions have been reported in the literature for releasing the parent toxins through an alkaline hydrolysis step, in order to simplify their detection by HPLC-FLD or LC-MS. In order to clearly understand toxin stability and reaction end-point the binominous temperature/time course and base concentration were studied using naturally contaminated bivalve samples. The results showed a strong temperature dependence of the reaction. At 60 degrees C and 70 degrees C the hydrolysis was fast, and 40min were sufficient for maximal recovery of OA and DTX2, while at 40 degrees C and 50 degrees C it was only complete after 100min and 60min, respectively. At room temperature the reaction was slow and incomplete even after 2h. Stability of OA and DTX2 in semi-purified bivalve matrix at 70 degrees C for 2h was demonstrated. Concentrations of sodium hydroxide lower than 2.5M, corresponding to a final incubation concentration of 0.23M, resulted in incomplete release of parent toxins, demonstrating that high concentrations are needed when taking into account the dilution in the supernatant extract.

  16. Enzymatic hydrolysis of lactose of whey permeate

    Directory of Open Access Journals (Sweden)

    Karina Nascimento de Almeida

    2015-09-01

    Full Text Available The whey permeate is the residual of the concentration process of the whey proteins by ultrafiltration method. It contains important nutrients such as lactose, minerals and some proteins and lipids. It is without an ending industrial waste that causes serious damage to the environment. For its full use the lactose must be hydrolyzed to enable its consumption by intolerant people. The enzymatic hydrolysis by lactase (β-galactosidase of Kluyveromyces lactis yeast is a safe method that does not compromise the integrity of other nutrients, enabling further use of the permeate as a raw material. This study aimed to perform tests of enzymatic hydrolysis of lactose in whey permeate formulations in a concentration of 0.2%, 0.7% and 1% at 30, 60 and 90 minutes with pH 6.3 medium and 37 °C. The reactions were monitored by high performance liquid chromatography which showed that the enzyme concentration of 0.7% at time 30 minutes formulations became safe for consumption by lactose intolerant people, according to minimum levels established by law.

  17. Pungent Components from Thioglucosides in Armoracia rusticana Grown in China, Obtained by Enzymatic Hydrolysis

    OpenAIRE

    Rong Li; Jimmy C. Yu; Zi-Tao Jiang

    2006-01-01

    The conditions of enzymatic hydrolysis of thioglucosides, which are the precursors of the pungent components in Armoracia rusticana grown in China, were studied. The effects of incubation time, temperature, pH and the addition of ascorbic acid on the hydrolysis of thioglucosides were determined. The optimum hydrolytic conditions for the pungent components from thioglucosides were time, 120 min; temperature, 65 oC; pH=4.0 and ascorbic acid, 2 mg/g. The mixture of pungent components in a pale-y...

  18. Combined heat treatment and acid hydrolysis of cassava grate waste (CGW) biomass for ethanol production

    Energy Technology Data Exchange (ETDEWEB)

    Agu, R.C.; Amadife, A.E.; Ude, C.M.; Onyia, A.; Ogu, E.O. [Enugu State Univ. of Science and Technology (Nigeria). Faculty of Applied Natural Sciences; Okafor, M.; Ezejiofor, E. [Nnamdi Azikiwe Univ., Awka (Nigeria). Dept. of Applied Microbiology

    1997-12-31

    The effect of combined heat treatment and acid hydrolysis (various concentrations) on cassava grate waste (CGW) biomass for ethanol production was investigated. At high concentrations of H{sub 2}SO{sub 4} (1--5 M), hydrolysis of the CGW biomass was achieved but with excessive charring or dehydration reaction. At lower acid concentrations, hydrolysis of CGW biomass was also achieved with 0.3--0.5 M H{sub 2}SO{sub 4}, while partial hydrolysis was obtained below 0.3 M H{sub 2}SO{sub 4} (the lowest acid concentration that hydrolyzed CGW biomass) at 120 C and 1 atm pressure for 30 min. A 60% process efficiency was achieved with 0.3 M H{sub 2}SO{sub 4} in hydrolyzing the cellulose and lignin materials present in the CGW biomass. High acid concentration is therefore not required for CGW biomass hydrolysis. The low acid concentration required for CGW biomass hydrolysis, as well as the minimal cost required for detoxification of CGW biomass because of low hydrogen cyanide content of CGW biomass would seem to make this process very economical. From three liters of the CGW biomass hydrolysate obtained from hydrolysis with 0.3M H{sub 2}SO{sub 4}, ethanol yield was 3.5 (v/v%) after yeast fermentation. However, although the process resulted in gainful utilization of CGW biomass, additional costs would be required to effectively dispose new by-products generated from CGW biomass processing.

  19. Characteristic Studies of Micron Zinc Particle Hydrolysis in a Fixed Bed Reactor

    Directory of Open Access Journals (Sweden)

    Lv Ming

    2015-09-01

    Full Text Available Zinc fuel is considered as a kind of promising energy sources for marine propeller. As one of the key steps for zinc marine energy power system, zinc hydrolysis process had been studied experimentally in a fixed bed reactor. In this study, we focus on the characteristics of micron zinc particle hydrolysis. The experimental results suggested that the steam inner diffusion is the controlling step of accumulative zinc particles hydrolysis reaction at a relative lower temperature and a relative higher water partial pressure. In other conditions, the chemical reaction kinetics was the controlling step. And two kinds of chemical reaction kinetics appeared in experiments: the surface reaction and the gas-gas reaction. The latter one occurs usually for larger zinc particles and high reaction temperature. Temperature seems to be one of the most important parameters for the dividing of different reaction mechanisms. Several parameters of the hydrolysis process including heating rate, water partial pressure, the particle size and temperature were also studied in this paper. Results show that the initial reaction temperature of zinc hydrolysis in fixed bed is about 410°C. And the initial reaction temperature increases as the heating rate increases and as the water partial pressure decreases. The total hydrogen yield increases as the heating rate decreases, as the water partial pressure increases, as the zinc particle size decreases, and as the reaction temperature increases. A hydrogen yield of more than 81.5% was obtained in the fixed bed experiments.

  20. Wet explosion pretreatment of sugarcane bagasse for enhanced enzymatic hydrolysis

    DEFF Research Database (Denmark)

    Biswas, Rajib; Uellendahl, Hinrich; Ahring, Birgitte Kiær

    2014-01-01

    .7% of the theoretical maximum value. Pretreatment at 200 C with oxygen exhibited enhanced enzymatic efficiency but lower xylose recovery and formation of the degradation products such as acetate, furfural and HMF of 7.6, 3.3 and 1.0 g/L, respectively. In the hydrolysis, the total sugars (glucose + xylose) yielded...

  1. Total syntheses of hyperforin and papuaforins A-C, and formal synthesis of nemorosone through a gold(I)-catalyzed carbocyclization.

    Science.gov (United States)

    Bellavance, Gabriel; Barriault, Louis

    2014-06-23

    The remarkable biological activities of polyprenylated polycyclic acylphloroglucinols (PPAPs) combined with their highly decorated bicyclo[3.3.1]nonane-2,4,9-trione frameworks have inspired synthetic organic chemists over the last decade. The concise total syntheses of four natural products PPAPs; hyperforin and papuaforins A-C, and the formal synthesis of nemorosone are reported. Key to the realization of this strategy is the short and scalable synthesis of densely substituted PPAP scaffolds through a gold(I)-catalyzed 6-endo-dig carbocyclization of cyclic enol ethers for late-stage functionalization. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Atroposelective Synthesis of Axially Chiral Biaryls by Palladium-Catalyzed Asymmetric C-H Olefination Enabled by a Transient Chiral Auxiliary.

    Science.gov (United States)

    Yao, Qi-Jun; Zhang, Shuo; Zhan, Bei-Bei; Shi, Bing-Feng

    2017-06-01

    Atroposelective synthesis of axially chiral biaryls by palladium-catalyzed C-H olefination, using tert-leucine as an inexpensive, catalytic, and transient chiral auxiliary, has been realized. This strategy provides a highly efficient and straightforward access to a broad range of enantioenriched biaryls in good yields (up to 98 %) with excellent enantioselectivities (95 to >99 % ee). Kinetic resolution of trisubstituted biaryls bearing sterically more demanding substituents is also operative, thus furnishing the optically active olefinated products with excellent selectivity (95 to >99 % ee, s-factor up to 600). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Processing of micro-nano bacterial cellulose with hydrolysis method as a reinforcing bioplastic

    Science.gov (United States)

    Maryam, Maryam; Dedy, Rahmad; Yunizurwan, Yunizurwan

    2017-01-01

    Nanotechnology is the ability to create and manipulate atoms and molecules on the smallest of scales. Their size allows them to exhibit novel and significantly improved physical, chemical, biological properties, phenomena, and processes because of their size. The purpose of this research is obtaining micro-nano bacterial cellulose as reinforcing bioplastics. Bacterial cellulose (BC) was made from coconut water for two weeks. BC was dried and grinded. Bacterial cellulose was given purification process with NaOH 5% for 6 hours. Making the micro-nano bacterial cellulose with hydrolysis method. Hydrolysis process with hydrochloric acid (HCl) at the conditions 3,5M, 55°C, 6 hours. Drying process used spray dryer. The hydrolysis process was obtained bacterial cellulose with ±7 μm. The addition 2% micro-nano bacterial cellulose as reinforcing in bioplastics composite can improve the physical characteristics.

  4. Processing of micro-nano bacterial cellulose with hydrolysis method as a reinforcing bioplastic

    International Nuclear Information System (INIS)

    Maryam, Maryam; Yunizurwan, Yunizurwan; Dedy, Rahmad

    2017-01-01

    Nanotechnology is the ability to create and manipulate atoms and molecules on the smallest of scales. Their size allows them to exhibit novel and significantly improved physical, chemical, biological properties, phenomena, and processes because of their size. The purpose of this research is obtaining micro-nano bacterial cellulose as reinforcing bioplastics. Bacterial cellulose (BC) was made from coconut water for two weeks. BC was dried and grinded. Bacterial cellulose was given purification process with NaOH 5% for 6 hours. Making the micro-nano bacterial cellulose with hydrolysis method. Hydrolysis process with hydrochloric acid (HCl) at the conditions 3,5M, 55°C, 6 hours. Drying process used spray dryer. The hydrolysis process was obtained bacterial cellulose with ±7 μm. The addition 2% micro-nano bacterial cellulose as reinforcing in bioplastics composite can improve the physical characteristics. (paper)

  5. Alpha 1-adrenergic receptor-mediated phosphoinositide hydrolysis and prostaglandin E2 formation in Madin-Darby canine kidney cells. Possible parallel activation of phospholipase C and phospholipase A2

    International Nuclear Information System (INIS)

    Slivka, S.R.; Insel, P.A.

    1987-01-01

    alpha 1-Adrenergic receptors mediate two effects on phospholipid metabolism in Madin-Darby canine kidney (MDCK-D1) cells: hydrolysis of phosphoinositides and arachidonic acid release with generation of prostaglandin E2 (PGE2). The similarity in concentration dependence for the agonist (-)-epinephrine in eliciting these two responses implies that they are mediated by a single population of alpha 1-adrenergic receptors. However, we find that the kinetics of the two responses are quite different, PGE2 production occurring more rapidly and transiently than the hydrolysis of phosphoinositides. The antibiotic neomycin selectively decreases alpha 1-receptor-mediated phosphatidylinositol 4,5-bisphosphate hydrolysis without decreasing alpha 1-receptor-mediated arachidonic acid release and PGE2 generation. In addition, receptor-mediated inositol trisphosphate formation is independent of extracellular calcium, whereas release of labeled arachidonic acid is largely calcium-dependent. Moreover, based on studies obtained with labeled arachidonic acid, receptor-mediated generation of arachidonic acid cannot be accounted for by breakdown of phosphatidylinositol monophosphate, phosphatidylinositol bisphosphate, or phosphatidic acid. Further studies indicate that epinephrine produces changes in formation or turnover of several classes of membrane phospholipids in MDCK cells. We conclude that alpha 1-adrenergic receptors in MDCK cells appear to regulate phospholipid metabolism by the parallel activation of phospholipase C and phospholipase A2. This parallel activation of phospholipases contrasts with models described in other systems which imply sequential activation of phospholipase C and diacylglycerol lipase or phospholipase A2

  6. A method for the production of D-tagatose using a recombinant Pichia pastoris strain secreting β-D-galactosidase from Arthrobacter chlorophenolicus and a recombinant L-arabinose isomerase from Arthrobacter sp. 22c

    Directory of Open Access Journals (Sweden)

    Wanarska Marta

    2012-08-01

    Full Text Available Abstract Background D-Tagatose is a natural monosaccharide which can be used as a low-calorie sugar substitute in food, beverages and pharmaceutical products. It is also currently being tested as an anti-diabetic and obesity control drug. D-Tagatose is a rare sugar, but it can be manufactured by the chemical or enzymatic isomerization of D-galactose obtained by a β-D-galactosidase-catalyzed hydrolysis of milk sugar lactose and the separation of D-glucose and D-galactose. L-Arabinose isomerases catalyze in vitro the conversion of D-galactose to D-tagatose and are the most promising enzymes for the large-scale production of D-tagatose. Results In this study, the araA gene from psychrotolerant Antarctic bacterium Arthrobacter sp. 22c was isolated, cloned and expressed in Escherichia coli. The active form of recombinant Arthrobacter sp. 22c L-arabinose isomerase consists of six subunits with a combined molecular weight of approximately 335 kDa. The maximum activity of this enzyme towards D-galactose was determined as occurring at 52°C; however, it exhibited over 60% of maximum activity at 30°C. The recombinant Arthrobacter sp. 22c L-arabinose isomerase was optimally active at a broad pH range of 5 to 9. This enzyme is not dependent on divalent metal ions, since it was only marginally activated by Mg2+, Mn2+ or Ca2+ and slightly inhibited by Co2+ or Ni2+. The bioconversion yield of D-galactose to D-tagatose by the purified L-arabinose isomerase reached 30% after 36 h at 50°C. In this study, a recombinant Pichia pastoris yeast strain secreting β-D-galactosidase Arthrobacter chlorophenolicus was also constructed. During cultivation of this strain in a whey permeate, lactose was hydrolyzed and D-glucose was metabolized, whereas D-galactose was accumulated in the medium. Moreover, cultivation of the P. pastoris strain secreting β-D-galactosidase in a whey permeate supplemented with Arthrobacter sp. 22c L-arabinose isomerase resulted in a 90% yield

  7. A method for the production of D-tagatose using a recombinant Pichia pastoris strain secreting β-D-galactosidase from Arthrobacter chlorophenolicus and a recombinant L-arabinose isomerase from Arthrobacter sp. 22c.

    Science.gov (United States)

    Wanarska, Marta; Kur, Józef

    2012-08-23

    D-Tagatose is a natural monosaccharide which can be used as a low-calorie sugar substitute in food, beverages and pharmaceutical products. It is also currently being tested as an anti-diabetic and obesity control drug. D-Tagatose is a rare sugar, but it can be manufactured by the chemical or enzymatic isomerization of D-galactose obtained by a β-D-galactosidase-catalyzed hydrolysis of milk sugar lactose and the separation of D-glucose and D-galactose. L-Arabinose isomerases catalyze in vitro the conversion of D-galactose to D-tagatose and are the most promising enzymes for the large-scale production of D-tagatose. In this study, the araA gene from psychrotolerant Antarctic bacterium Arthrobacter sp. 22c was isolated, cloned and expressed in Escherichia coli. The active form of recombinant Arthrobacter sp. 22c L-arabinose isomerase consists of six subunits with a combined molecular weight of approximately 335 kDa. The maximum activity of this enzyme towards D-galactose was determined as occurring at 52°C; however, it exhibited over 60% of maximum activity at 30°C. The recombinant Arthrobacter sp. 22c L-arabinose isomerase was optimally active at a broad pH range of 5 to 9. This enzyme is not dependent on divalent metal ions, since it was only marginally activated by Mg2+, Mn2+ or Ca2+ and slightly inhibited by Co2+ or Ni2+. The bioconversion yield of D-galactose to D-tagatose by the purified L-arabinose isomerase reached 30% after 36 h at 50°C. In this study, a recombinant Pichia pastoris yeast strain secreting β-D-galactosidase Arthrobacter chlorophenolicus was also constructed. During cultivation of this strain in a whey permeate, lactose was hydrolyzed and D-glucose was metabolized, whereas D-galactose was accumulated in the medium. Moreover, cultivation of the P. pastoris strain secreting β-D-galactosidase in a whey permeate supplemented with Arthrobacter sp. 22c L-arabinose isomerase resulted in a 90% yield of lactose hydrolysis, the complete utilization

  8. Occurrence of bioactive sphingolipids in meat and fish products

    DEFF Research Database (Denmark)

    Hellgren, Lars

    2001-01-01

    /neutral glycolipids varied from 1 to 2.9, while in poultry this ratio varied between 5.2 to 19.2 and in red meat it varied from 1.6 to 8.3. The fatty acid composition of sphingomyelin in fish was dominated by C24:1 (Delta (9)) or C22:1 (Delta (9)), while C16:0 and C18:0 were the dominating sphingomyelin species....... Therefore we investigated the contents of sphingomyelin and neutral glycosphingolipids in commonly consumed meat and fish products. Sphingomyelin and glycosphingolipids were found in all foodstuffs studied. The total amount varied between 118 +/- 17 nmol/g (cod) to 589 +/- 39 nmol/g (chicken leg). Generally......, lower amounts of sphingolipids were determined in fish meat than in red meat and poultry, while poultry was the richest source of this class of lipids. However, fish meat contained a relatively high content of neutral glycolipids compared with other types of meat. Thus, in fish the ratio sphingomyelin...

  9. Inhibition of cellulase-catalyzed lignocellulosic hydrolysis by iron and oxidative metal ions and complexes.

    Science.gov (United States)

    Tejirian, Ani; Xu, Feng

    2010-12-01

    Enzymatic lignocellulose hydrolysis plays a key role in microbially driven carbon cycling and energy conversion and holds promise for bio-based energy and chemical industries. Cellulases (key lignocellulose-active enzymes) are prone to interference from various noncellulosic substances (e.g., metal ions). During natural cellulolysis, these substances may arise from other microbial activities or abiotic events, and during industrial cellulolysis, they may be derived from biomass feedstocks or upstream treatments. Knowledge about cellulolysis-inhibiting reactions is of importance for the microbiology of natural biomass degradation and the development of biomass conversion technology. Different metal ions, including those native to microbial activity or employed for biomass pretreatments, are often tested for enzymatic cellulolysis. Only a few metal ions act as inhibitors of cellulases, which include ferrous and ferric ions as well as cupric ion. In this study, we showed inhibition by ferrous/ferric ions as part of a more general effect from oxidative (or redox-active) metal ions and their complexes. The correlation between inhibition and oxidation potential indicated the oxidative nature of the inhibition, and the dependence on air established the catalytic role that iron ions played in mediating the dioxygen inhibition of cellulolysis. Individual cellulases showed different susceptibilities to inhibition. It is likely that the inhibition exerted its effect more on cellulose than on cellulase. Strong iron ion chelators and polyethylene glycols could mitigate the inhibition. Potential microbiological and industrial implications of the observed effect of redox-active metal ions on enzymatic cellulolysis, as well as the prevention and mitigation of this effect in industrial biomass conversion, are discussed.

  10. Extraterrestrial material analysis: loss of amino acids during liquid-phase acid hydrolysis

    Science.gov (United States)

    Buch, Arnaud; Brault, Amaury; Szopa, Cyril; Freissinet, Caroline

    2015-04-01

    Searching for building blocks of life in extraterrestrial material is a way to learn more about how life could have appeared on Earth. With this aim, liquid-phase acid hydrolysis has been used, since at least 1970 , in order to extract amino acids and other organic molecules from extraterrestrial materials (e.g. meteorites, lunar fines) or Earth analogues (e.g. Atacama desert soil). This procedure involves drastic conditions such as heating samples in 6N HCl for 24 h, either under inert atmosphere/vacuum, or air. Analysis of the hydrolyzed part of the sample should give its total (free plus bound) amino acid content. The present work deals with the influence of the 6N HCl hydrolysis on amino acid degradation. Our experiments have been performed on a standard solution of 17 amino acids. After liquid-phase acid hydrolysis (6N HCl) under argon atmosphere (24 h at 100°C), the liquid phase was evaporated and the dry residue was derivatized with N-Methyl-N-(t-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) and dimethylformamide (DMF), followed by gas chromatography-mass spectrometry analysis. After comparison with derivatized amino acids from the standard solution, a significant reduction of the chromatographic peak areas was observed for most of the amino acids after liquid-phase acid hydrolysis. Furthermore, the same loss pattern was observed when the amino acids were exposed to cold 6N HCl for a short amount of time. The least affected amino acid, i.e. glycine, was found to be 73,93% percent less abundant compared to the non-hydrolyzed standard, while the most affected, i.e. histidine, was not found in the chromatograms after hydrolysis. Our experiments thereby indicate that liquid-phase acid hydrolysis, even under inert atmosphere, leads to a partial or total loss of all of the 17 amino acids present in the standard solution, and that a quick cold contact with 6N HCl is sufficient to lead to a loss of amino acids. Therefore, in the literature, the reported increase

  11. Regioselective C2 Oxidative Olefination of Indoles and Pyrroles through Cationic Rhodium(III)-Catalyzed C-H Bond Activation.

    Science.gov (United States)

    Li, Bin; Ma, Jianfeng; Xie, Weijia; Song, Haibin; Xu, Shansheng; Wang, Baiquan

    2013-09-02

    Be economic with your atoms! An efficient Rh-catalyzed oxidative olefination of indoles and pyrroles with broad substrate scope and tolerance is reported. The catalytic reaction proceeds with excellent regio- and stereoselectivity. The directing group N,N-dimethylcarbamoyl was crucial for the reaction and could be removed easily. Copyright © 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. RhII -Catalyzed β-C(sp2 )-H Alkylation of Enol Ethers, Enamides and Enecarbamates with α-Diazo Dicarbonyl Compounds.

    Science.gov (United States)

    McLarney, Brett D; Cavitt, Marchello A; Donnell, Theodore M; Musaev, Djamaladdin G; France, Stefan

    2017-01-23

    A Rh II -catalyzed method for intermolecular alkylation of the β-C(sp 2 )-H bond of enol ethers, enamides, and enecarbamates with α-diazo-1,3-dicarbonyl compounds is reported. The products are formed in up to 99 % yield and can be readily derivatized under a variety of conditions. By utilizing a combination of experimental and computational studies, the presumptive addition-elimination reaction mechanism was investigated and found to proceed under thermodynamic control at higher temperature. The acquired fundamental knowledge was translated into a strategic reaction design and yielded the first example of the β-C-H functionalizations of acyclic enol ethers using α-diazo-1,3-dicarbonyl compounds. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Effects of lipids on enzymatic hydrolysis and physical properties of starch.

    Science.gov (United States)

    Ai, Yongfeng; Hasjim, Jovin; Jane, Jay-lin

    2013-01-30

    This study aimed to understand effects of lipids, including corn oil (CO), soy lecithin (SL), palmitic acid (PA), stearic acid (SA), oleic acid (OA), and linoleic acid (LA), on the enzymatic hydrolysis and physical properties of normal corn (NCS), tapioca (TPS), waxy corn (WCS), and high-amylose corn (HA7) starch, and to elucidate mechanisms of interactions between the starches and lipids. After cooking with the lipids (10%, w/w, dsb), NCS, TPS, and HA7 showed significant decreases in enzymatic hydrolysis, and their DSC thermograms displayed amylose-lipid-complex dissociation peaks except with the CO. (13)C NMR spectra of amylodextrin with CO showed downfield changes in the chemical shifts of carbons 1 and 4 of the anhydroglucose unit, indicating helical complex formation. Generally, free fatty acids (FFAs) reduced, but SL increased the peak viscosities of starches. FFAs and SL decreased, but CO increased the gel strength of NCS. These lipids displayed little impacts on the enzymatic hydrolysis and physical properties of WCS because it lacked amylose. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Hydrolysis kinetics of astaxanthin esters and stability of astaxanthin of Haematococcus pluvialis during saponification.

    Science.gov (United States)

    Yuan, J P; Chen, F

    1999-01-01

    The reaction kinetics for the hydrolysis of astaxanthin esters and the degradation of astaxanthin during saponification of the pigment extract from the microalga Haematococcus pluvialis were investigated. Different concentrations of sodium hydroxide in methanol were used for the saponification under nitrogen in darkness at ambient temperature (22 degrees C) followed by the analysis of astaxanthins and other carotenoids using an HPLC method. The concentration of methanolic NaOH solution was important for promoting the hydrolysis of astaxanthin esters and minimizing the degradation of astaxanthin during saponification. With a higher concentration of methanolic NaOH solution, the reaction rate of hydrolysis was high, but the degradation of astaxanthin occurred significantly. The rate constants of the hydrolysis reaction (first order) of astaxanthin esters and the degradation reaction (zero-order) of astaxanthin were directly proportional to the concentration of sodium hydroxide in the saponified solution. Although the concentration of sodium hydroxide in the saponified solution was 0.018 M, complete hydrolysis of astaxanthin esters was achieved in 6 h for different concentrations (10-100 mg/L) of pigment extracts. Results also indicated that a higher temperature should be avoided to minimize the degradation of astaxanthin. In addition, during saponification, no loss of lutein, beta-carotene, and canthaxanthin was found.

  15. Optimization of upstream and development of cellulose hydrolysis process for cellulosic bio-ethanol production

    International Nuclear Information System (INIS)

    Bae, Hyeun Jong; Wi, Seung Gon; Lee, Yoon Gyo; Kim, Ho Myung; Kim, Su Bae

    2011-10-01

    The purpose of this project is optimization of upstream and development of cellulose hydrolysis process for cellulosic bio-ethanol production. The 2nd year Research scope includes: 1) Optimization of pre-treatment conditions for enzymatic hydrolysis of lignocellulosic biomass and 2) Demonstration of enzymatic hydrolysis by recombinant enzymes. To optimize the pretreatment, we applied two processes: a wet process (wet milling + popping), and dry process (popping + dry milling). Out of these, the wet process presented the best glucose yield with a 93.1% conversion, while the dry process yielded 69.6%, and the unpretreated process yielded <20%. The recombinant cellulolytic enzymes showed very high specific activity, about 80-1000 times on CMC and 13-70 times on filter paper at pH 3.5 and 55 .deg. C

  16. Supramolecular Complexes Formed by the Self-assembly of Hydrophobic Bis(Zn(2+)-cyclen) Complexes, Copper, and Di- or Triimide Units for the Hydrolysis of Phosphate Mono- and Diesters in Two-Phase Solvent Systems (Cyclen=1,4,7,10-Tetraazacyclododecane).

    Science.gov (United States)

    Hisamatsu, Yosuke; Miyazawa, Yuya; Yoneda, Kakeru; Miyauchi, Miki; Zulkefeli, Mohd; Aoki, Shin

    2016-01-01

    We previously reported on supramolecular complexes 4 and 5, formed by the 4 : 4 : 4 or 2 : 2 : 2 assembly of a dimeric zinc(II) complex (Zn2L(1)) having 2,2'-bipyridyl linker, dianion of cyanuric acid (CA) or 5,5-diethylbarbituric acid (Bar), and copper(II) ion (Cu(2+)) in an aqueous solution. The supermolecule 4 possesses Cu2(μ-OH)2 centers and catalyzes hydrolysis of phosphate monoester dianion, mono(4-nitrophenyl)phosphate (MNP), at neutral pH. In this manuscript, we report on design and synthesis of hydrophobic supermolecules 9 and 10 by 4 : 4 : 4 and 2 : 2 : 2 self-assembly of hydrophobic Zn2L(2) and Zn2L(3) containing long alkyl chains, CA or Bar, and Cu(2+) and their phosphatase activity for the hydrolysis of MNP and bis(4-nitrophenyl)phosphate (BNP) in two-phase solvent systems. We assumed that the Cu2(μ-OH)2 active sites of 9 and 10 would be more stable in organic solvent than in aqueous solution and that product inhibition of the supermolecules might be avoided by the release of HPO4(2-) into the aqueous layer. The findings indicate that 9 and 10 exhibit phosphatase activity in the two-phase solvent system, although catalytic turnover was not observed. Furthermore, the hydrolysis of BNP catalyzed by the hydrophobic 2 : 2 : 2 supermolecules in the two-phase solvent system is described.

  17. Neutral fat hydrolysis and long-chain fatty acid oxidation during anaerobic digestion of slaughterhouse wastewater.

    Science.gov (United States)

    Masse, L; Massé, D I; Kennedy, K J; Chou, S P

    2002-07-05

    Neutral fat hydrolysis and long-chain fatty acid (LCFA) oxidation rates were determined during the digestion of slaughterhouse wastewater in anaerobic sequencing batch reactors operated at 25 degrees C. The experimental substrate consisted of filtered slaughterhouse wastewater supplemented with pork fat particles at various average initial sizes (D(in)) ranging from 60 to 450 microm. At the D(in) tested, there was no significant particle size effect on the first-order hydrolysis rate. The neutral fat hydrolysis rate averaged 0.63 +/- 0.07 d(-1). LCFA oxidation rate was modelled using a Monod-type equation. The maximum substrate utilization rate (kmax) and the half-saturation concentration (Ks) averaged 164 +/- 37 mg LCFA/L/d and 35 +/- 31 mg LCFA/L, respectively. Pork fat particle degradation was mainly controlled by LCFA oxidation rate and, to a lesser extent, by neutral fat hydrolysis rate. Hydrolysis pretreatment of fat-containing wastewaters and sludges should not substantially accelerate their anaerobic treatment. At a D(in) of 450 microm, fat particles were found to inhibit methane production during the initial 20 h of digestion. Inhibition of methane production in the early phase of digestion was the only significant effect of fat particle size on anaerobic digestion of pork slaughterhouse wastewater. Soluble COD could not be used to determine the rate of lipid hydrolysis due to LCFA adsorption on the biomass.

  18. Hydrolysis of protein and model dipeptide substrated by attached and nonattached marine Pseudomonas sp. strain NCIMB 2021

    International Nuclear Information System (INIS)

    Griffith, P.C.; Fletcher, M.

    1991-01-01

    Rates of substrate hydrolysis by nonattached bacteria and by bacteria attached to particles derived from marine diatom frustules were estimated by using two substrates, a dipeptide analog and a protein. Adsorption of the two substrates onto the particles was also evaluated. Methyl-coumarinyl-amide-leucine (MCA-leucine) was used to estimate hydrolysis of dipeptides by measuring an increase in fluorescence as MCA-leucine was hydrolyzed to leucine and the fluorochrome methylcoumarin. To examine hydrolysis of a larger molecule, was prepared a radiolabeled protein by 14 C-methylation of bovine serum albumin. The rate of protein hydrolysis in samples of particle-attached or nonattached bacteria was estimated by precipitating all nonhydrolyzed protein with cold trichloroacetic acid and then determining the trichloroacetic acid-soluble radiolabeled material, which represented methyl- 14 C-peptides and -amino acids. About 25% of the MCA-leucine adsorbed to the particles. MCA-leucine was hydrolyzed faster by nonattached than attached bacteria, which was probably related to its tendency to remain dissolved in the liquid phase. In contrast, almost 100% of the labeled protein adsorbed to the particles. Accordingly, protein was much less available to nonattached bacteria but was rapidly hydrolyzed by attached bacteria

  19. Effect of the chloride ions on the hydrolysis of praseodymium in a 2M ion force media

    International Nuclear Information System (INIS)

    Lopez G, H.; Jimenez R, M.; Solache R, M.; Rojas H, A.

    2004-01-01

    The constants of the product of solubility and the first of hydrolysis were determined of the Praseodymium in media 2M of NaClO 4 and 2M of NaCl, to 303 K and under conditions free of CO 2 . The diagram of solubility was obtained (pPr (ac) - pC H ), by means of a radiochemical method and with it was established the pC H that limit the saturation and non saturation areas; that diagram allowed, also, to calculate the constant of the product of solubility. Also, it was adjusted with the polynomial of solubility equation, that it allowed to determine and to check the values of the constants of the product of solubility and the first of hydrolysis. Independently, it was determined the first constant of hydrolysis of the element, by means of potentiometric titrations whose data were treated with the computer program named SUPERQUAD and with the adjustment of the equation of the average number of bonds. It was also calculates the log constant β Pr,Cl of the specie PrCI 2+ starting from the hydrolysis constants obtained in the perchlorate and chloride media. (Author)

  20. The Study of NADPH-Dependent Flavoenzyme-Catalyzed Reduction of Benzo[1,2-c]1,2,5-oxadiazole N-Oxides (Benzofuroxans

    Directory of Open Access Journals (Sweden)

    Jonas Šarlauskas

    2014-12-01

    Full Text Available The enzymatic reactivity of a series of benzo[1,2-c]1,2,5-oxadiazole N-oxides (benzofuroxans; BFXs towards mammalian single-electron transferring NADPH:cytochrome P-450 reductase (P-450R and two-electron (hydride transferring NAD(PH:quinone oxidoreductase (NQO1 was examined in this work. Since the =N+ (→OO− moiety of furoxan fragments of BFXs bears some similarity to the aromatic nitro-group, the reactivity of BFXs was compared to that of nitro-aromatic compounds (NACs whose reduction mechanisms by these and other related flavoenzymes have been extensively investigated. The reduction of BFXs by both P-450R and NQO1 was accompanied by O2 uptake, which was much lower than the NADPH oxidation rate; except for annelated BFXs, whose reduction was followed by the production of peroxide. In order to analyze the possible quantitative structure-activity relationships (QSARs of the enzymatic reactivity of the compounds, their electron-accepting potency and other reactivity indices were assessed by quantum mechanical methods. In P-450R-catalyzed reactions, both BFXs and NACs showed the same reactivity dependence on their electron-accepting potency which might be consistent with an “outer sphere” electron transfer mechanism. In NQO1-catalyzed two-electron (hydride transferring reactions, BFXs acted as more efficient substrates than NACs, and the reduction efficacy of BFXs by NQO1 was in general higher than by single-electron transferring P-450R. In NQO1-catalyzed reactions, QSARs obtained showed that the reduction efficacy of BFXs, as well as that of NACs, was determined by their electron-accepting potency and could be influenced by their binding mode in the active center of NQO1 and by their global softness as their electronic characteristic. The reductive conversion of benzofuroxan by both flavoenzymes yielded the same reduction product of benzofuroxan, 2,3-diaminophenazine, with the formation of o-benzoquinone dioxime as a putative primary

  1. Kinetics and mechanism of hydrolysis of benzimidazolylcarbamates

    OpenAIRE

    Norberto, F. P.; Santos, S. P.; Iley, J.; Silva, D. B.; Corte Real, M.

    2007-01-01

    Synthesis of new 2-aminobenzimidazole-1-carbamates was accomplished by carbamoylation of 2-aminobenzimidazole using different substituted phenyl chloroformates. The aqueous hydrolysis of the new compounds was examined in the pH range 1-13 at 25 ºC. The evaluated kinetic parameters led to the conclusion that up to pH 4 reaction proceeds by a bimolecular attack of water to the N-protonated substrate. This is the first time this behavior is described for carbamates, and can be ascribed to the hi...

  2. Effects of cooking methods and starch structures on starch hydrolysis rates of rice.

    Science.gov (United States)

    Reed, Michael O; Ai, Yongfeng; Leutcher, Josh L; Jane, Jay-lin

    2013-07-01

    This study aimed to understand effects of different cooking methods, including steamed, pilaf, and traditional stir-fried, on starch hydrolysis rates of rice. Rice grains of 3 varieties, japonica, indica, and waxy, were used for the study. Rice starch was isolated from the grain and characterized. Amylose contents of starches from japonica, indica, and waxy rice were 13.5%, 18.0%, and 0.9%, respectively. The onset gelatinization temperature of indica starch (71.6 °C) was higher than that of the japonica and waxy starch (56.0 and 56.8 °C, respectively). The difference was attributed to longer amylopectin branch chains of the indica starch. Starch hydrolysis rates and resistant starch (RS) contents of the rice varieties differed after they were cooked using different methods. Stir-fried rice displayed the least starch hydrolysis rate followed by pilaf rice and steamed rice for each rice variety. RS contents of freshly steamed japonica, indica, and waxy rice were 0.7%, 6.6%, and 1.3%, respectively; those of rice pilaf were 12.1%, 13.2%, and 3.4%, respectively; and the stir-fried rice displayed the largest RS contents of 15.8%, 16.6%, and 12.1%, respectively. Mechanisms of the large RS contents of the stir-fried rice were studied. With the least starch hydrolysis rate and the largest RS content, stir-fried rice would be a desirable way of preparing rice for food to reduce postprandial blood glucose and insulin responses and to improve colon health of humans. © 2013 Institute of Food Technologists®

  3. Novel Platinum-Catalyzed Ring-Opening of 1,2-Cyclopropanated Sugars with Alcohols

    DEFF Research Database (Denmark)

    Beyer, Jürgen; Madsen, Robert

    1998-01-01

    Reaction of 1,2-cyclopropanated sugars with a catalytic amount ofZeise's dimer [Pt(C2H4)Cl2]2 and an alcohol gives 2-C-branched glycosides by a novel platinum catalyzed ring-opening. A wide variety of alcohols can participate in this ring-opening reaction giving 2-C-branched glycosides ranging from...

  4. Enantioconvergent hydrolysis of racemic styrene oxide at high concentration by a pair of novel epoxide hydrolases into (R)-phenyl-1,2-ethanediol.

    Science.gov (United States)

    Wang, Rui; Hu, Die; Zong, Xuncheng; Li, Jinping; Ding, Lei; Wu, Minchen; Li, Jianfang

    2017-12-01

    To prepare (R)-phenyl-1,2-ethanediol ((R)-PED) with high enantiomeric excess (ee p ) and yield from racemic styrene oxide (rac-SO) at high concentration by bi-enzymatic catalysis. The bi-enzymatic catalysis was designed for enantioconvergent hydrolysis of rac-SO by a pair of novel epoxide hydrolases (EHs), a Vigna radiata EH3 (VrEH3) and a variant (AuEH2 A250I ) of Aspergillus usamii EH2. The simultaneous addition mode of VrEH3 and AuEH2 A250I , exhibiting the highest average turnover frequency (aTOF) of 0.12 g h -1 g -1 , was selected, by which rac-SO (10 mM) was converted into (R)-PED with 92.6% ee p and 96.3% yield. Under the optimized reaction conditions: dry weight ratio 14:1 of VrEH3-expressing E. coli/vreh3 to AuEH2 A250I -expressing E. coli/Aueh2 A250I and reaction at 20 °C, rac-SO (10 mM) was completely hydrolyzed in 2.3 h, affording (R)-PED with 98% ee p . At the weight ratio 0.8:1 of rac-SO to two mixed dry cells, (R)-PED with 97.4% ee p and 98.7% yield was produced from 200 mM (24 mg/ml) rac-SO in 10.5 h. Enantioconvergent hydrolysis of rac-SO at high concentration catalyzed by both VrEH3 and AuEH2 A250I is an effective method for preparing (R)-PED with high ee p and yield.

  5. Pd(II)-Catalyzed Alkylation of Tertiary Carbon via Directing-Group-Mediated C(sp(3))-H Activation: Synthesis of Chiral 1,1,2-Trialkyl Substituted Cyclopropanes.

    Science.gov (United States)

    Hoshiya, Naoyuki; Takenaka, Kei; Shuto, Satoshi; Uenishi, Jun'ichi

    2016-01-04

    A Pd(OAc)2-catalyzed alkylation reaction of the tertiary carbon of chiral cyclopropane substrates with alkyl iodides and bromides via C(sp(3))-H activation has been developed. This is an elusive example of a C-H activation-mediated alkylation of tertiary carbon to effectively construct a quaternary carbon center. The alkylation proceeded with various alkyl halides, including those of functional groups, to provide a variety of chiral cis- and trans-1,1,2,-trialkyl substituted cyclopropanes of medicinal chemical importance.

  6. Preparation of micro-fibrillated cellulose based on sugar palm ijuk (Arenga pinnata) fibres through partial acid hydrolysis

    Science.gov (United States)

    Saputro, A.; Verawati, I.; Ramahdita, G.; Chalid, M.

    2017-07-01

    The aim of this study was to isolate and characterized micro-fibrillated cellulose (MFC) from sugar palm/ijuk fibre (Arenga pinnata) by partial sulfuric acid hydrolysis. Cellulose fibre was prepared by repeated treatments with 5 wt% sodium hydroxide 2 h at 80°C, followed by bleaching with 1.7 wt% sodium chlorite for 2 h at 80°C in acidic environment under stirring. MFC was prepared by partial hydrolysis with sulfuric acid in various concentrations (30, 40, 50, and 60 % for 45 min at 45 °C) under stirring. Fourier Transform Infrared, Field Emission Scanning Electron Microscope, Thermo Gravimetric Analyzer and X-ray Diffraction characterized cellulose fibre and MFC. FTIR measurements showed that alkaline and bleaching treatments were effective to remove non-cellulosic constituents such as wax, lignin and hemicellulose. FESEM observation revealed conversion into more clear surface and defibrillation of cellulosic fibre after pre-treatments. XRD measurement revealed increase in crystallinity after pre-treatments and acid hydrolysis from 54.4 to 87.8%. Thermal analysis showed that increasing acid concentration reduced thermal stability.

  7. Sphingomyelin synthesis in rat liver occurs predominantly at the cis and medial cisternae of the Golgi apparatus

    International Nuclear Information System (INIS)

    Futerman, A.H.; Stieger, B.; Hubbard, A.L.; Pagano, R.E.

    1990-01-01

    The intracellular site of sphingomyelin (SM) synthesis was examined in subcellular fractions from rat liver using a radioactive ceramide analog N-([1-14C]hexanoyl)-D-erythro-sphingosine. This lipid readily transferred from a complex with bovine serum albumin to liver fractions without disrupting the membranes, and was metabolized to radioactive SM. To prevent degradation of the newly synthesized SM to ceramide, all experiments were performed in the presence of EDTA to minimize neutral sphingomyelinase activity and at neutral pH to minimize acid sphingomyelinase activity. An intact Golgi apparatus fraction gave an 85-98-fold enrichment of SM synthesis and a 58-83-fold enrichment of galactosyltransferase activity. Controlled trypsin digestion demonstrated that SM synthesis was localized to the lumen of intact Golgi apparatus vesicles. Although small amounts of SM synthesis were detected in plasma membrane and rough microsome fractions, after accounting for contamination by Golgi apparatus membranes, their combined activity contributed less than 13% of the total SM synthesis in rat liver. Subfractions of the Golgi apparatus were obtained and characterized by immunoblotting and biochemical assays using cis/medial (mannosidase II) and trans (sialyltransferase and galactosyltransferase) Golgi apparatus markers. The specific activity of SM synthesis was highest in enriched cis and medial fractions but far lower in a trans fraction. We conclude that SM synthesis in rat liver occurs predominantly in the cis and medial cisternae of the Golgi apparatus and not at the plasma membrane or endoplasmic reticulum as has been previously suggested

  8. Improving the enzymatic hydrolysis of thermo-mechanical fiber from Eucalyptus urophylla by a combination of hydrothermal pretreatment and alkali fractionation.

    Science.gov (United States)

    Sun, Shaoni; Cao, Xuefei; Sun, Shaolong; Xu, Feng; Song, Xianliang; Sun, Run-Cang; Jones, Gwynn Lloyd

    2014-01-01

    The recalcitrance of lignocellulosic biomass is a major limitation for its conversion into biofuels by enzymatic hydrolysis. The use of a pretreatment technology is an essential step to diminish biomass recalcitrance for bioethanol production. In this study, a two-step pretreatment using hydrothermal pretreatment at various temperatures and alkali fractionation was performed on eucalyptus fiber. The detailed chemical composition, physicochemical characteristics, and morphology of the pretreated fibers in each of the fractions were evaluated to advance the performance of eucalyptus fiber in enzymatic digestibility. The hydrothermal pretreatment (100 to 220°C) significantly degraded hemicelluloses, resulting in an increased crystallinity of the pretreated fibers. However, as the pretreatment temperature reached 240°C, partial cellulose was degraded, resulting in a reduced crystallinity of cellulose. As compared to the hydrothermal pretreatment alone, a combination of hydrothermal and alkali treatments significantly removed hemicelluloses and lignin, resulting in an improved enzymatic hydrolysis of the cellulose-rich fractions. As compared with the raw fiber, the enzymatic hydrolysis rate increased 1.1 to 8.5 times as the hydrothermal pretreatment temperature increased from 100 to 240°C. Interestingly, after a combination of hydrothermal pretreatment and alkali fractionation, the enzymatic hydrolysis rate increased 3.7 to 9.2 times. Taking into consideration the consumption of energy and the production of xylo-oligosaccharides and lignin, an optimum pretreatment condition was found to be hydrothermal pretreatment at 180°C for 30 min and alkali fractionation with 2% NaOH at 90°C for 2.5 h, in which 66.3% cellulose was converted into glucose by enzymatic hydrolysis. The combination of hydrothermal pretreatment and alkali fractionation was a promising method to remove hemicelluloses and lignin as well as overcome the biomass recalcitrance for enzymatic hydrolysis

  9. Hydrothermal synthesis of uranyl squarates and squarate-oxalates: hydrolysis trends and in situ oxalate formation.

    Science.gov (United States)

    Rowland, Clare E; Cahill, Christopher L

    2010-07-19

    We report the synthesis of two uranyl squarates and two mixed-ligand uranyl squarate-oxalates from aqueous solutions under hydrothermal conditions. These products exhibit a range of uranyl building units from squarates with monomers in (UO(2))(2)(C(4)O(4))(5).6NH(4).4H(2)O (1; a = 16.731(17) A, b = 7.280(8) A, c = 15.872(16) A, beta = 113.294(16) degrees , monoclinic, P2(1)/c) and chains in (UO(2))(2)(OH)(2)(H(2)O)(2)(C(4)O(4)) (2; a = 12.909(5) A, b = 8.400(3) A, c = 10.322(4) A, beta = 100.056(7) degrees , monoclinic, C2/c) to two squarate-oxalate polymorphs with dimers in (UO(2))(2)(OH)(C(4)O(4))(C(2)O(4)).NH(4).H(2)O (3; a = 9.0601(7) A, b = 15.7299(12) A, c = 10.5108(8) A, beta = 106.394(1) degrees , monoclinic, P2(1)/n; and 4; a = 8.4469(6) A, b = 7.7589(5) A, c = 10.5257(7) A, beta = 105.696(1) degrees , monoclinic, P2(1)/m). The dominance at low pH of monomeric species and the increasing occurrence of oligomeric species with increasing pH suggests that uranyl hydrolysis, mUO(2)(2+) + nH(2)O right harpoon over left harpoon [(UO(2))(m)(OH)(n)](2m-n) + nH(+), has a significant role in the identity of the inorganic building unit. Additional factors that influence product assembly include in situ hydrolysis of squaric acid to oxalic acid, dynamic metal to ligand concentration, and additional binding modes resulting from the introduction of oxalate anions. These points and the effects of uranyl hydrolysis with changing pH are discussed in the context of the compounds presented herein.

  10. Tissue-specific biomass recalcitrance in corn stover pretreated with liquid hot-water: enzymatic hydrolysis (part 1).

    Science.gov (United States)

    Zeng, Meijuan; Ximenes, Eduardo; Ladisch, Michael R; Mosier, Nathan S; Vermerris, Wilfred; Huang, Chia-Ping; Sherman, Debra M

    2012-02-01

    Lignin content, composition, distribution as well as cell wall thickness, structures, and type of tissue have a measurable effect on enzymatic hydrolysis of cellulose in lignocellulosic feedstocks. The first part of our work combined compositional analysis, pretreatment and enzyme hydrolysis for fractionated pith, rind, and leaf tissues from a hybrid stay-green corn, in order to identify the role of structural characteristics on enzyme hydrolysis of cell walls. The extent of enzyme hydrolysis follows the sequence rind cellulose to glucose in 24 h in the best cases. Physical fractionation of corn stalks or other C(4) grasses into soft and hard tissue types could reduce cost of cellulose conversion by enabling reduced enzyme loadings to hydrolyze soft tissue, and directing the hard tissue to other uses such as thermal processing, combustion, or recycle to the land from which the corn was harvested. Copyright © 2011 Wiley Periodicals, Inc.

  11. Kinetics of cellobiose hydrolysis using cellobiase composites from Trichoderma reesei and Aspergillus niger

    Energy Technology Data Exchange (ETDEWEB)

    Grous, W.; Converse, A.; Grethlein, H.; Lynd, L.

    1985-01-01

    The enzymatic hydrolysis of cellulose to glucose involves the formation of cellobiose as an intermediate. It has been found necessary to add cellobiase from Aspergillus niger (NOVO) to the cellobiase component of Trichoderma reesei mutant Rut C-30 (Natick) cellulase enzymes in order to obtain after 48 h complete conversion of the cellobiose formed in the enzymatic hydrolysis of biomass. This study of the cellobiase activity of these two enzyme sources was undertaken as a first step in the formation of a kinetic model for cellulose hydrolysis that can be used in process design. In order to cover the full range of cellobiose concentrations, it was necessary to develop separate kinetic parameters for high- and low-concentration ranges of cellobiose for the enzymes from each organism. Competitive glucose inhibition was observed with the enzymes from both organisms. Substrate inhibition was observed only with the A. niger enzymes.

  12. Production of fermentable sugars by combined chemo-enzymatic hydrolysis of cellulosic material for bioethanol production

    Directory of Open Access Journals (Sweden)

    M. Idrees

    2014-06-01

    Full Text Available To change the recalcitrant nature of the lignocellulosic material for maximum hydrolysis yield, a comprehensive study was done by using sulphuric acid as an exclusive catalyst for the pretreatment process. The enzymatic digestibility of the biomass [Water Hyacinth: Eichhornia crassipes] after pretreatment was determined by measuring the hydrolysis yield of the pretreated material obtained from twenty four different pretreatment conditions. These included different concentrations of sulphuric acid (0.0, 1.0, 2.0 and 3.0%, at two different temperatures (108 and 121 ºC for different residence times (1.0, 2.0 and 3.0h.The highest reducing sugar yield (36.65 g/L from enzymatic hydrolysis was obtained when plant material was pretreated at 121 ºC for 1.0 h residence time using 3.0% (v/v sulphuric acid and at 1:10 (w/v solid to liquid ratio. The total reducing sugars obtained from the two-stage process (pretreatment + enzymatic hydrolysis was 69.6g/L. The resulting sugars were fermented into ethanol by using Saccharomyces cerevisiae. The ethanol yield from the enzymatic hydrolyzate was 95.2% of the theoretical yield (0.51g/g glucose, as determined by GS-MS, and nearly 100% since no reducing sugars were detected in the fermenting media by TLC and DNS analysis.

  13. Au-Cu core-shell nanocube-catalyzed click reactions for efficient synthesis of diverse triazoles.

    Science.gov (United States)

    Madasu, Mahesh; Hsia, Chi-Fu; Huang, Michael H

    2017-06-01

    Au-Cu core-shell nanocubes and octahedra synthesized in aqueous solution were employed to catalyze a 1,3-dipolar cycloaddition reaction between phenylacetylene and benzyl azide in water at 50 °C for 3 h. Interestingly, the nanocubes were far more efficient in catalyzing this reaction, giving 91% yield of a regioselective 1,4-triazole product, while octahedra only recorded 46% yield. The Au-Cu nanocubes were subsequently employed to catalyze the click reaction between benzyl azide and a broad range of aromatic and aliphatic alkynes. The product yields ranged from 78 to 99%. Clearly the Au-Cu cubes exposing {100} surfaces are an excellent and green catalyst for click reactions.

  14. Unprecedentedly mild direct Pd-catalyzed arylation of oxazolo[4,5-b]pyridine

    DEFF Research Database (Denmark)

    Zhuravlev, Fedor

    2006-01-01

    Pd-catalyzed C-2 arylation of oxazolo[4,5-b]pyridine proceeds efficiently at 30 degrees C and tolerates a variety of aryl halides, including derivatized amino acids for which no racemization was observed during the reaction. Experimental evidence for facile deprotonation of oxazolo[4,5-b...

  15. Vitamin B2 content determination in liver paste by using acid and acid-enzyme hydrolysis

    Directory of Open Access Journals (Sweden)

    Basić Zorica

    2007-01-01

    Full Text Available Background/Aim. Vitamin B2 is available in foodstuff in the form of coenzyme and in free form. For its content determination a few procedures should be performed (deliberation from a complex, extraction of free and deliberated form and detection, identification and quantification. There is a particular problem in determination of vitamin B2 in the meat products. For a determination of total vitamin B2 content in liver paste two preparation procedures are compared: acid and acid-enzymatic hydrolysis. The aim of this study thus, was to compare the effectiveness of these two different procedures for vitamin B2 content determination in liver paste. Methods. High pressure liquid chromatography (HPLC method with fluorescence detector, as specific and adequately sensitive for the foodstuff of a complex composition with a natural vitamin content, was used for determination of vitamin B2 in liver paste. Acid hydrolysis was performed with the application 0.1 M hydrochloric acid in a pressure cooker, and enzymatic hydrolysis was performed with the 10% takadiastase on 45 ºC within four hours. Ten samples of liver paste from the supply of the Serbian Army were examined. Separation was performed on the analytical column Nucleosil 50−5 C18 with mobile phase 450 ml CH3OH + 20 ml 5 mM CH3COONH4, and detection on the fluorescent detector with the variable wave length. Both methods were validated: examining a detection limit, quantification limit, specificity (because of a possible B2 vitamin interference with reagents, linearity of a peak area and standard concentration of B2 vitamin ratio in the range from 0.05 μg/ml to 2 μg/ml, precision for the 0.05 μg/ml concentration and recovery. Results. All the previously examined parameters validated both methods as specific, precise and reproductive, with a high recovery (98.5% for acid and 98.2% for acid - enzymatic hydrolysis, as well as linearity in a range that significantly superseded the expected content in

  16. The Hydrolysis of Di-Isopropyl Methylphosphonate in Ground Water

    Energy Technology Data Exchange (ETDEWEB)

    Sega, G.A., Tomkins, B.A., Griest, W.H., Bayne, C.K.

    1997-12-31

    Di-isopropyl methylphosphonate (DIMP) is a byproduct from the manufacture of the nerve agent Sarin. The persistence of DIMP in the ground water is an important question in evaluating the potential environmental impacts of DIMP contamination. The half-life of DIMP in ground water at 10 deg C was estimated to be 500 years with a 95% confidence interval of 447 to 559 years from measurements of the hydrolysis rates at temperatures between 70 to 98 deg C.Extrapolation of the kinetics to 10 deg C used the Arrhenius equation, and calculation of the half-life assumed first-order kinetics. Inorganic phosphate was not detected.

  17. Synthesis, characterization and in vitro hydrolysis of a gemfibrozil-nicotinic acid codrug for improvement of lipid profile.

    Science.gov (United States)

    Qandil, Amjad M; Rezigue, Meriem M; Tashtoush, Bassam M

    2011-06-14

    Combination therapy of fibrates and nicotinic acid has been reported to be synergistic. Herein, we describe a covalent codrug of gemfibrozil (GEM) and nicotinic acid (NA) that was synthesized and characterized by (1)H NMR, (13)C NMR, FT-IR, MS analysis and elemental analysis. A validated HPLC method was developed that allows for the accurate quantitative determination of the codrug and its hydrolytic products that are formed during the in vitro chemical and enzymatic hydrolysis. The physico-chemical properties of codrug were improved compared to its parent drugs in term of water solubility and partition coefficient. The kinetics of hydrolysis of the codrug was studied using accelerated hydrolysis experiments at high temperatures in aqueous phosphate buffer solution in pH 1.2, 6.8 and 7.4. Using the Arrhenius equation, the extrapolated half-life at 37°C were 289 days at pH 1.2 for the codrug and 130 and 20,315 days at pH 6.8 for the codrug and gemfibrozil 2-hydroxyethyl ester (GHEE), respectively. The shortest half-lives were at pH 7.4; 42 days for the codrug and 5837 days for GHEE, respectively. The hydrolysis of the latter was studied, alone, at 80°C and pH 1.2 and compared to its hydrolysis when it is produced from the codrug using similar conditions. The k(obs) was found in both cases to be 1.60×10(-3)h(-1). The half-lives in plasma were 35.24 min and 26.75 h for the codrug and GHEE, respectively. With regard to liver homogenate, the hydrolysis half-lives were 1.96 min and 48.13 min for the codrug and GHEE, respectively. It can be expected that in vivo, the codrug will liberate NA immediately in plasma then GEM will be liberated from its 2-hydroxyethyl ester in the liver. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Active Site Dynamics in Substrate Hydrolysis Catalyzed by DapE Enzyme and Its Mutants from Hybrid QM/MM-Molecular Dynamics Simulation.

    Science.gov (United States)

    Dutta, Debodyuti; Mishra, Sabyashachi

    2017-07-27

    The mechanism of the catalytic hydrolysis of N-succinyl diaminopimelic acid (SDAP) by the microbial enzyme DapE in its wild-type (wt) form as well as three of its mutants (E134D, H67A, and H349A) is investigated employing a hybrid quantum mechanics/molecular mechanics (QM/MM) method coupled with molecular dynamics (MD) simulations, wherein the time evolution of the atoms of the QM and MM regions are obtained from the forces acting on the individual atoms. The free-energy profiles along the reaction coordinates of this multistep hydrolysis reaction process are explored using a combination of equilibrium and nonequilibrium (umbrella sampling) QM/MM-MD simulation techniques. In the enzyme-substrate complexes of wt-DapE and the E134D mutant, nucleophilic attack is found to be the rate-determining step involving a barrier of 15.3 and 21.5 kcal/mol, respectively, which satisfactorily explains the free energy of activation obtained from kinetic experiments in wt-DapE-SDAP (15.2 kcal/mol) and the 3 orders of magnitude decrease in the catalytic activity due to E134D mutation. The catalysis is found to be quenched in the H67A and H349A mutants of DapE due to conformational rearrangement in the active site induced by the absence of the active site His residues that prohibits activation of the catalytic water molecule.

  19. Synergistic antioxidant activity of milk sphingomyeline and its sphingoid base with α-tocopherol on fish oil triacylglycerol.

    Science.gov (United States)

    Shimajiri, Junki; Shiota, Makoto; Hosokawa, Masashi; Miyashita, Kazuo

    2013-08-21

    The effects of milk phospholipids (PLs), sphingolipids (SLs), and their sphingoid backbone on the oxidation of fish oil triacylglycerol (TAG) were examined with or without α-tocopherol. All compounds had little effect on the TAG oxidation in the absence of α-tocopherol. On the other hand, they could act synergistically with α-tocopherol. The highest synergistic activity was shown by sphingoid bases, followed by sphingomyelin (SPM) and other amine-containing PLs and SLs. This result showed that the synergistic activity increased with an increasing concentration of amine group of PLs, SLs, or sphingoid bases in the reaction mixture. The comparison of changes in α-tocopherol content in fish oil TAG and tricaprylin suggested that antioxidant compounds would be formed from the amine group and the lipid oxidation products in a mild oxidation condition controlled by α-tocopherol.

  20. Paraoxonase (PON1 and PON3 polymorphisms: impact on liver expression and atorvastatin-lactone hydrolysis

    Directory of Open Access Journals (Sweden)

    Stephan eRiedmaier

    2011-07-01

    Full Text Available Atorvastatin δ-lactone, a major, pharmacologically inactive metabolite, has been associated with toxicity. In a previous study we showed that polymorphisms of UGT1A3 influence atorvastatin δ-lactone formation. Here we investigated the reverse reaction, atorvastatin δ-lactone hydrolysis, in a human liver bank. Screening of microarray data revealed paraoxonases PON1 and PON3 among 17 candidate esterases. Microsomal δ-lactone hydrolysis was significantly correlated to PON1 and PON3 protein (rs=0.60; rs=0.62, respectively; P<0.0001. PON1 and PON3 were strongly correlated to each other (rs=0.60 but PON1 was shown to be more extensively glycosylated than PON3. In addition a novel splice variant of PON3 was identified. Genotyping of 40 polymorphisms within the PON-locus identified PON1 promoter polymorphisms (-108T>C, -832G>A, -1741G>A and a tightly linked group of PON3 polymorphisms (-4984A>G, -4105G>A, -1091A>G, -746C>T and F21F to be associated with changes in atorvastatin δ-lactone hydrolysis and expression of PON1 but not PON3. However, carriers of the common PON1 polymorphisms L55M or Q192R showed no difference in δ-lactone hydrolysis or PON expression. Haplotype analysis revealed decreased δ-lactone hydrolysis in carriers of the most common haplotype *1 compared to carriers of haplotypes *2, *3, *4 and *7. Analysis of non-genetic factors showed association of hepatocellular and cholangiocellular carcinoma with decreased PON1 and PON3 expression, respectively. Increased C-reactive protein and γ-glutamyl transferase levels were associated with decreased protein expression of both enzymes, and increased bilirubin levels, cholestasis and pre-surgical exposure to omeprazole or pantoprazole were related to decreased PON3 protein. In conclusion, PON-locus polymorphisms affect PON1 expression whereas non-genetic factors have an effect on PON1 and PON3 expression. This may influence response to therapy or adverse events in statin treatment.