- Synthetic application and activity of cutinase in an aqueous, miniemulsion model system: Hexyl octanoate synthesis
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Cutinase has been shown to be a promising biocatalyst for applications in processes targeted for industrial scale. This work aims to further contribute for highlighting such role, by bestowing detailed insight on the application of cutinase for the synthesis of value added compounds in miniemulsion environments (oil-in-water). The synthesis of hexyl octanoate was used as model system, due to the relevance of this compound for industrial applications as flavor and fragrance agent. The nature, specificity and selectivity of the catalyst enable operation under mild reaction conditions, without undesirable side reactions, leading to a very pure product. A high conversion yield, about 86%, for an enzyme concentration of 5 mg ml-1, was achieved. Hexyl octanoate synthesis and cutinase activity for different acid: alcohol molar ratio (R), under different pH environments, were evaluated. A maximum cutinase activity of 2.20 μmol mg-1 min-1 was observed for R = 0.5, which was tentatively ascribed to the stabilizing effect of hexanol on the miniemulsion. It is thus considered that the accumulation of the hydrophobic hexyl octanoate inside the droplets stabilize the miniemulsion system.
- De Barros, Dragana P.C.,Fernandes, Pedro,Cabral, Joaquim M.S.,Fonseca, Luis P.
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- Rational redesign of Candida antarctica lipase B for the ring opening polymerization of d,d-lactide
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Based on molecular modelling, the enzyme Candida antarctica lipase B was redesigned as a catalyst for the ring opening polymerization of d,d-lactide. Two mutants with 90-fold increased activity as compared to the wild-type enzyme were created. In a preparative synthesis of poly(d,d-lactide) the mutants greatly improved the rate and the degree of polymerization.
- Takwa, Mohamad,Larsen, Marianne Wittrup,Hult, Karl,Martinelle, Mats
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- Organometallic substrates of enzymes: lipase catalysed transesterifications in organic solvents via O-stannyl ethers
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Lipases from pig pancreas and from Chromobacterium viscosum (but not from Candida cylindracea) catalyze transesterification reactions between ethyl esters of carboxylic acids and tributylstannyl ethers of primary and secondary alcohols.At concentrations 1M or higher in anhydrous hydrocarbons, use of these nucleophilic derivatives of alcohols gives reaction rates ca. three times higher than those for the corresponding alcohols.
- Therisod, Michel
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- Lipase chemoselectivity towards alcohol and thiol acyl acceptors in a transacylation reaction
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The lipase chemoselectivity towards an alcohol and a thiol was investigated for the two lipases Candida antarctica lipase B (CalB) and Rhizomucor miehei lipase (Rml). Hexanol and hexanethiol were used as acyl acceptors in a transacylation reaction with ethyl octanoate in cyclohexane. CalB showed the highest chemoselectivity ratio (kcat/KM) OH/(kcat/KM)SH, of 88,000 while the ratio for Rml was 1200. That could be compared with the ratio, k OH/kSH, of 120 for the non-catalyzed reaction. Thus, the enzyme contribution to the chemoselectivity between hexanol and hexanethiol was 730 for CalB and 10 for Rml. High KM values displayed towards hexanethiol (above 1.8 M) were the largest contribution to the selectivity. No saturation was achieved. The KM values were more than two orders of magnitude higher than those of hexanol.
- Hedfors, Cecilia,Hult, Karl,Martinelle, Mats
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- Kinetic study on the enzymatic esterification of octanoic acid and hexanol by immobilized Candida antarctica lipase B
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This study investigates reaction kinetics of the esterification of octanoic acid and hexanol into hexyloctanoate, catalyzed by an immobilized Candida antarctica lipase (Novozym435). The product is consid-ered natural and used as a fresh vegetable and fruity flavour additive in food, cosmetic and pharmaceuticalproducts. The reaction is performed in n-decane as the solvent, to improve enzyme stability and toincrease the reaction yield. The influence of substrate concentration on hexyl octanoate synthesis isinvestigated over a wide range up to 2 M. The observed bi-substrate inhibition pattern follows a Ping-Pong bi-bi mechanism with dead-end inhibition by both substrates and, based on the proposed model, thekinetic constants of the esterification reaction are estimated. These parameters are verified to be intrin-sic neither external nor internal mass transfer resistances are significant for the examined reactionsystem and are essential to extend analysis to a large-scale process and for a wide range of operatingconditions. The progress of the reaction is also observed and the kinetic model is validated by fittingexperimental progress curves with two different concentrations of biocatalyst. Effects of biphasicity ofthe reaction system, inhibition by the ester produced and the influence of the reverse reaction have beenalso evaluated.
- Lopresto, Catia Giovanna,Calabr, Vincenza,Woodley, John M.,Tufvesson, P?r
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- Carboxylic Acid Reductase Can Catalyze Ester Synthesis in Aqueous Environments
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Most of the well-known enzymes catalyzing esterification require the minimization of water or activated substrates for activity. This work reports a new reaction catalyzed by carboxylic acid reductase (CAR), an enzyme known to transform a broad spectrum of carboxylic acids into aldehydes, with the use of ATP, Mg2+, and NADPH as co-substrates. When NADPH was replaced by a nucleophilic alcohol, CAR from Mycobacterium marinum can catalyze esterification under aqueous conditions at room temperature. Addition of imidazole, especially at pH 10.0, significantly enhanced ester production. In comparison to other esterification enzymes such as acyltransferase and lipase, CAR gave higher esterification yields in direct esterification under aqueous conditions. The scalability of CAR catalyzed esterification was demonstrated for the synthesis of cinoxate, an active ingredient in sunscreen. The CAR esterification offers a new method for green esterification under high water content conditions.
- Pongpamorn, Pornkanok,Kiattisewee, Cholpisit,Kittipanukul, Narongyot,Jaroensuk, Juthamas,Trisrivirat, Duangthip,Maenpuen, Somchart,Chaiyen, Pimchai
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supporting information
p. 5749 - 5753
(2021/02/01)
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- Second-Generation meta-Phenolsulfonic Acid-Formaldehyde Resin as a Catalyst for Continuous-Flow Esterification
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A second-generation m-phenolsulfonic acid-formaldehyde resin (PAFR II) catalyst was prepared by condensation polymerization of sodium m-phenolsulfonate and paraformaldehyde in an aqueous H2SO4 solution. This reusable, robust acid resin catalyst was improved in both catalytic activity and stability, maintaining the characteristics of the previous generation catalyst (p-phenolsulfonic acid-formaldehyde resin). PAFR II was applied in the batchwise and continuous-flow direct esterification without water removal and provided higher product yields in continuous-flow esterification than any other commercial ion-exchanged acid catalyst tested.
- Hu, Hao,Ota, Hajime,Baek, Heeyoel,Shinohara, Kenta,Mase, Toshiaki,Uozumi, Yasuhiro,Yamada, Yoichi M. A.
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supporting information
p. 160 - 163
(2020/01/02)
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- Non-plasmonic metal nanoparticles as visible light photocatalysts for the selective oxidation of aliphatic alcohols with molecular oxygen at near ambient conditions
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Nanoparticles (NPs) of Pd and Pt were used for the selective oxidation of aliphatic alcohols with molecular oxygen as an oxidant at near ambient temperatures under visible light irradiation. Distinct final products were obtained under identical reaction conditions, aliphatic esters formed over the Pd NPs while aldehydes formed over the Pt NPs. The reason for this different product selectivity is proven to be due to the much stronger interaction of Pd NPs with alcohol and aldehyde compared to Pt NPs. The photocatalytic activity is tuneable by light intensity or a moderate change in the reaction temperature.
- Tana, Tana,Guo, Xiao-Wei,Xiao, Qi,Huang, Yiming,Sarina, Sarina,Christopher, Phillip,Jia, Jianfeng,Wu, Haishun,Zhu, Huaiyong
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p. 11567 - 11570
(2016/10/03)
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- Effective esterification of carboxylic acids using (6-oxo-6H-pyridazin-1-yl)phosphoric acid diethyl ester as novel coupling agents
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(6-Oxo-6H-pyridazin-1-yl)phosphoric acid diethyl esters (3) are efficient and selective coupling agents for equimolar esterification of carboxylic acids and alcohols. Esterification of aliphatic and aromatic carboxylic acids with aliphatic and aromatic alcohols using 3 afforded the corresponding esters chemoselectively in good to excellent yield.
- Won, Ju-Eun,Kim, Ho-Kyun,Kim, Jeum-Jong,Yim, Heong-Seup,Kim, Min-Jung,Kang, Seung-Beom,Chung, Hyun-A.,Lee, Sang-Gyeong,Yoon, Yong-Jin
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p. 12720 - 12730
(2008/03/14)
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