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Karl Hult - One of the best experts on this subject based on the ideXlab platform.
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Rational engineering of Candida Antarctica lipase B for selective monoacylation of diols
Chemical communications (Cambridge England), 2012Co-Authors: Anders Hamberg, Steffen Maurer, Karl HultAbstract:The enzyme Candida Antarctica lipase B was subjected to site directed mutagenesis suggested by molecular modelling. The selectivity for the enzyme increased towards a range of diols over their corresponding monoesters as an effect of the mutations.
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Selectivity towards itaconic acid esters by Candida Antarctica lipase B and variants
2011Co-Authors: Cecilia Hedfors, Peter Hendil-forssell, Per-olof Syrén, Mohamad Takwa, Karl Hult, Mats MartinelleAbstract:Enzyme selectivity means that the enzyme´s preferences towards competing substrates will be different. In this thesis, the enzyme selectivity has been studied for utilization in synthesis of functionalized macromonomers. The aim was to study how the inherent –or introduced – selectivity of lipases can be used to introduce thiol‐ or enefunctionalities into short polyesters. Thiol‐ and ene‐functionalized renewable organic precursor molecules in combination with thiol‐ene click chemistry opens up for a sustainable material production. Lipases do not normally affect ene‐moieties and the preference towards thiols is low, enabling introduction of these functional groups for further modifications. In addition, lipases have been shown to be good catalysts in the formation of polyesters, both via ring‐opening and polycondensation polymerization. In paper I Candida Antarctica lipase B was used to end‐functionalize poly(e‐caprolactone) with free thiols in a one‐pot reaction. The advantage of using achemoselective lipase as catalyst was that no protection of the thiol was needed. The chemoselectivity displayed by Candida Antarctica lipase B turned out to be 88 000 in favour of the alcohol (paper II). Rhizomucor miehei lipase showed less pronounced chemoselectivity. The largest contribution to the selectivities was derived from the more than two orders of magnitude higer KM towards the thiol compared to the alcohol. Thiols can be cross‐linked with enes in radical reactions to form networks, enabling formation of materials. One promising renewable molecule containing an acrylate moiety is itaconic acid. In paper III the selectivity towards the two esters in dimethyl itaconate was investigated and the active site of Candida Antarctica lipase B was redesigned to generate variants with increased and decreased selectivity. One variant showed 14‐fold higher selectivity and could regioselectively add dimethyl itaconate onto a diol. This variant could be used in end‐functionalizations of polymers, introducing acrylate‐ester end‐groups. The enzyme selectivity towards lactones and their corresponding polyesters is of importance when designing a ring‐opening polymerization reaction. In paper IV Candida Antarctica lipase B was found to prefer ω‐pentadecalactone and polyesters over e‐caprolactone ten‐fold, while Humicola insolens cutinase preferred e‐caprolactone and its corresponding polyester four‐fold over ω‐pentadecalactone and its polyester. From a selectivity point of view, Candida Antarctica lipase B and Humicola insolens cutinase would be equally good in ring‐opening polymerization of ω‐pentadecalactone, while in the case of e‐caprolactone Humicola insolens cutinase would be the preferred choice.
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Screening and production of Pseudozyma (Candida) Antarctica lipase B in Pichia pastoris using the GAP promoter as alternative to the AOX promoter expression system
2010Co-Authors: Marianne Larsen Wittrup, Sven-olof Enfors, Mehmedalija Jahic, Karl HultAbstract:Screening and production of Pseudozyma (Candida) Antarctica lipase B in Pichia pastoris using the GAP promoter as alternative to the AOX promoter expression system
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Direct Epoxidation in Candida Antarctica Lipase B Studied by Experiment and Theory
Chembiochem : a European journal of chemical biology, 2008Co-Authors: Maria Svedendahl, Karl Hult, Peter Carlqvist, Cecilia Branneby, Olof Allnér, Anton Frise, Per Berglund, Tore BrinckAbstract:Candida Antarctica lipase B (CALB) is a promiscuous serine hydrolase that, besides its native function, catalyzes different side reactions, such as direct epoxidation. A single-point mutant of CALB ...
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One-Pot Difunctionalization of Poly(ω-pentadecalactone) with Thiol-Thiol or Thiol-Acrylate Groups, Catalyzed by Candida Antarctica Lipase B
Macromolecular Rapid Communications, 2006Co-Authors: Mohamad Takwa, Karl Hult, Eva Malmström, Neil Simpson, Mats MartinelleAbstract:An enzymatic one-pot procedure has been developed for the synthesis of difunetional polyesters containing terminal thiols and acrylates. Candida Antarctica lipase B was used as a catalyst for the r ...
Mats Martinelle - One of the best experts on this subject based on the ideXlab platform.
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Selectivity towards itaconic acid esters by Candida Antarctica lipase B and variants
2011Co-Authors: Cecilia Hedfors, Peter Hendil-forssell, Per-olof Syrén, Mohamad Takwa, Karl Hult, Mats MartinelleAbstract:Enzyme selectivity means that the enzyme´s preferences towards competing substrates will be different. In this thesis, the enzyme selectivity has been studied for utilization in synthesis of functionalized macromonomers. The aim was to study how the inherent –or introduced – selectivity of lipases can be used to introduce thiol‐ or enefunctionalities into short polyesters. Thiol‐ and ene‐functionalized renewable organic precursor molecules in combination with thiol‐ene click chemistry opens up for a sustainable material production. Lipases do not normally affect ene‐moieties and the preference towards thiols is low, enabling introduction of these functional groups for further modifications. In addition, lipases have been shown to be good catalysts in the formation of polyesters, both via ring‐opening and polycondensation polymerization. In paper I Candida Antarctica lipase B was used to end‐functionalize poly(e‐caprolactone) with free thiols in a one‐pot reaction. The advantage of using achemoselective lipase as catalyst was that no protection of the thiol was needed. The chemoselectivity displayed by Candida Antarctica lipase B turned out to be 88 000 in favour of the alcohol (paper II). Rhizomucor miehei lipase showed less pronounced chemoselectivity. The largest contribution to the selectivities was derived from the more than two orders of magnitude higer KM towards the thiol compared to the alcohol. Thiols can be cross‐linked with enes in radical reactions to form networks, enabling formation of materials. One promising renewable molecule containing an acrylate moiety is itaconic acid. In paper III the selectivity towards the two esters in dimethyl itaconate was investigated and the active site of Candida Antarctica lipase B was redesigned to generate variants with increased and decreased selectivity. One variant showed 14‐fold higher selectivity and could regioselectively add dimethyl itaconate onto a diol. This variant could be used in end‐functionalizations of polymers, introducing acrylate‐ester end‐groups. The enzyme selectivity towards lactones and their corresponding polyesters is of importance when designing a ring‐opening polymerization reaction. In paper IV Candida Antarctica lipase B was found to prefer ω‐pentadecalactone and polyesters over e‐caprolactone ten‐fold, while Humicola insolens cutinase preferred e‐caprolactone and its corresponding polyester four‐fold over ω‐pentadecalactone and its polyester. From a selectivity point of view, Candida Antarctica lipase B and Humicola insolens cutinase would be equally good in ring‐opening polymerization of ω‐pentadecalactone, while in the case of e‐caprolactone Humicola insolens cutinase would be the preferred choice.
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One-Pot Difunctionalization of Poly(ω-pentadecalactone) with Thiol-Thiol or Thiol-Acrylate Groups, Catalyzed by Candida Antarctica Lipase B
Macromolecular Rapid Communications, 2006Co-Authors: Mohamad Takwa, Karl Hult, Eva Malmström, Neil Simpson, Mats MartinelleAbstract:An enzymatic one-pot procedure has been developed for the synthesis of difunetional polyesters containing terminal thiols and acrylates. Candida Antarctica lipase B was used as a catalyst for the r ...
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Thiol end-functionalization of poly(ε-caprolactone), catalyzed by Candida Antarctica lipase B
Macromolecules, 2005Co-Authors: Cecilia Hedfors, Karl Hult, Emma Östmark, Eva Malmström, Mats MartinelleAbstract:The use of Candida Antarctica Lipase B (CALB) chemoselective catalyst in the Thiol End-Functionalization of Poly(e-caprolacetone) was discussed. Thiol-functionalization of poly(e-caprolacetone)(PCL ...
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Expression in Pichia pastoris of Candida Antarctica Lipase B and Lipase B Fused to a Cellulose-Binding Domain
Protein expression and purification, 2001Co-Authors: Johanna C. Rotticci-mulder, Karl Hult, Malin Gustavsson, Mats Holmquist, Mats MartinelleAbstract:Candida Antarctica lipase B (CALB) and C. Antarctica lipase B fused to a cellulose-binding domain (CBD-CALB) were expressed functionally in the methylotrophic yeast Pichia pastoris. The cellulose-b ...
Takashi Nakane - One of the best experts on this subject based on the ideXlab platform.
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Production of Biosurfactants by Candida Antarctica
Biochemical Engineering for 2001, 1992Co-Authors: Dai Kitamoto, Hiroshi Yanagishita, Takeyoshi Fuzishiro, Takashi NakaneAbstract:We previously reported that the growing cells of Candida Antarctica strain T-34 produced a large amount of biosurfactants, a mixture of mannosylerythritol lipids (MEL) from different vegetabLe oils [1]. A resting-cell method have been widely applied to the production of biosurfactants, because the method is considered to need less costs than a growing-cell method, i.e., a conventional fermentation method [2]. To improve the yield and to facilitate the recovery of MEL, we tried to produce MEL by using resting cells of the yeast. We also studied the interfacial properties and antimicrobial activities of MEL.
Thorleif Anthonsen - One of the best experts on this subject based on the ideXlab platform.
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Biocatalytic resolution of saphenic acid. Substrate preferences for lipases A and B from Candida Antarctica
Arkivoc, 2008Co-Authors: Freddy Tjosås, Thorleif Anthonsen, Elisabeth Egholm JacobsenAbstract:Efficient methods for synthesis of enantiomerically pure enantiomers of a series of secondary alcohols and butanoates have been performed by kinetic resolution of the racemic alcohols and esters catalyzed by lipase B from Candida Antarctica (Novozym 435). The effect of the substrate structure on E was different for transesterifications of alcohols in organic media as compared to hydrolysis of esters in buffer. The influence of different acyl donors on the enantioselectivity has also been investigated.Derivatives of 1-phenoxy-2-alkanols have been kinetically resolved by esterification with irreversible and reversible acyl donors using lipase B from Candida Antarctica (Novozym 435) as catalyst. Esterifications in eight different solvents with different water activity have been performed. For 3-bromo-1-phenoxy-2-propanol the E-values in all of the solvents were higher when the water activity was increased. The water content of the various reaction media at the same water activity was also determined.In esterifications of secondary alcohols catalyzed by immobilized lipase B from Candida Antarctica (Novozym 435) the E-values decreased during the reaction. Hydrolysis of the corresponding butanoates showed the opposite effect. When an enantiopure (R)-alcohol, related but different, was added to the transesterification reaction, the E-value was significantly enhanced.Decreasing enantioselectivity (E-value) by conversion has also been observed in transesterification reactions of secondary alcohols catalyzed by a pure protein formulation of lipase B from Candida Antarctica (Novozym 525 F). It can be concluded that the immobilization of Novozym 435 not was the reason for the decrease in E-value which was observed. Addition of a range of enantiopure alcohols caused a temporary increase in enzyme selectivity in the transesterification reaction of 3-chloro-1-phenoxy- 2-propanol with vinyl butanoate.Enantioselective hydrolyses and ammonolyses of diethyl 3-hydroxyglutarate and dimethyl 3-hydroxyglutarate gave a maximum of 91 and 98 % enantiomeric excess, respectively, with use of immobilized lipase B from Candida Antarctica (Novozym 435). Ee´s were determined using chiral GLC of the mono amides and achiral GLC of diastereomeric derivatives of the monoesters. The catalyst was re-used more than ten times with retention of high activity and selectivity.Biocatalytic asymmetrizations of diethyl 3-hydroxyglutarate furnish a route to enantiomers of ethyl 4-cyano-3-hydroxybutanoate. The enantiopreference of different enzymes has been established by chiral chromatography. Conclusive evidence for absolute configurations has been provided by X-ray crystallographic structure determination of co-crystals of the predominant monoester (3S)-3-hydroxy pentanedioic monoethyl ester with (R)-phenylethylamine. The predominant enantiopure monoester produced by ammonolysis of diethyl 3-hydroxyglutarate catalyzed by immobilized lipase B from Candida Antarctica (Novozym 435) was ethyl (3S)-4-carbamoyl-3- hydroxybutanoate. It was converted to ethyl (3S)-4-cyano-3-hydroxybutanoate in high yield and enantiomeric excess.
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Enantiopure derivatives of 1,2-alkanediols: substrate requirements of lipase B from Candida Antarctica.
Chirality, 2000Co-Authors: Elisabeth Egholm Jacobsen, Bård Helge Hoff, Thorleif AnthonsenAbstract:Efficient methods for synthesis of enantiomerically pure enantiomers of a series of secondary alcohols and butanoates have been performed by kinetic resolution of the racemic alcohols and esters catalyzed by lipase B from Candida Antarctica (Novozym 435). The effect of the substrate structure on E was different for transesterifications of alcohols in organic media as compared to hydrolysis of esters in buffer. The influence of different acyl donors on the enantioselectivity has also been investigated.Derivatives of 1-phenoxy-2-alkanols have been kinetically resolved by esterification with irreversible and reversible acyl donors using lipase B from Candida Antarctica (Novozym 435) as catalyst. Esterifications in eight different solvents with different water activity have been performed. For 3-bromo-1-phenoxy-2-propanol the E-values in all of the solvents were higher when the water activity was increased. The water content of the various reaction media at the same water activity was also determined.In esterifications of secondary alcohols catalyzed by immobilized lipase B from Candida Antarctica (Novozym 435) the E-values decreased during the reaction. Hydrolysis of the corresponding butanoates showed the opposite effect. When an enantiopure (R)-alcohol, related but different, was added to the transesterification reaction, the E-value was significantly enhanced.Decreasing enantioselectivity (E-value) by conversion has also been observed in transesterification reactions of secondary alcohols catalyzed by a pure protein formulation of lipase B from Candida Antarctica (Novozym 525 F). It can be concluded that the immobilization of Novozym 435 not was the reason for the decrease in E-value which was observed. Addition of a range of enantiopure alcohols caused a temporary increase in enzyme selectivity in the transesterification reaction of 3-chloro-1-phenoxy- 2-propanol with vinyl butanoate.Enantioselective hydrolyses and ammonolyses of diethyl 3-hydroxyglutarate and dimethyl 3-hydroxyglutarate gave a maximum of 91 and 98 % enantiomeric excess, respectively, with use of immobilized lipase B from Candida Antarctica (Novozym 435). Ee´s were determined using chiral GLC of the mono amides and achiral GLC of diastereomeric derivatives of the monoesters. The catalyst was re-used more than ten times with retention of high activity and selectivity.Biocatalytic asymmetrizations of diethyl 3-hydroxyglutarate furnish a route to enantiomers of ethyl 4-cyano-3-hydroxybutanoate. The enantiopreference of different enzymes has been established by chiral chromatography. Conclusive evidence for absolute configurations has been provided by X-ray crystallographic structure determination of co-crystals of the predominant monoester (3S)-3-hydroxy pentanedioic monoethyl ester with (R)-phenylethylamine. The predominant enantiopure monoester produced by ammonolysis of diethyl 3-hydroxyglutarate catalyzed by immobilized lipase B from Candida Antarctica (Novozym 435) was ethyl (3S)-4-carbamoyl-3- hydroxybutanoate. It was converted to ethyl (3S)-4-cyano-3-hydroxybutanoate in high yield and enantiomeric excess.
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Enantiopure derivatives of 1,2-alkanediols: substrate requirements of lipase B from Candida Antarctica.
Chirality, 2000Co-Authors: Elisabeth Egholm Jacobsen, Bård Helge Hoff, Thorleif AnthonsenAbstract:Efficient methods for kinetic resolution of 1-phenoxy-2-butanol, 1-phenylmethoxy-2-butanol, and 1-phenoxy-2-pentanol were developed using lipase B from Candida Antarctica as catalyst. Resolutions were performed in order to investigate the substrate requirements needed to obtain a high E-value. The effect of the substrate structure on E is different for transesterifications in organic media as compared to hydrolysis. The influence of different acyl donors on the E-value was also investigated.
Włodzimierz Bednarski - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of ascorbyloleate by immobilized Candida Antarctica lipases
Process Biochemistry, 2005Co-Authors: Marek Adamczak, Uwe T. Bornscheuer, Włodzimierz BednarskiAbstract:The lipase-catalyzed synthesis of ascorbyloleate was studied using different preparations of lipases from Candida Antarctica. Conversion to ascorbyloleate was influenced by the type of lipase, the carrier used for immobilization, water activity and organic solvent. The highest conversion (63%) was found using Chirazyme L-2 immobilized on carrier C2, in acetone, using methyloleate as acyl donor (4-fold excess), at water activity 0.11 and in the presence of molecular sieves.
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Influence of medium composition and aeration on the synthesis of biosurfactants produced by Candida Antarctica
Biotechnology Letters, 2000Co-Authors: Marek Adamczak, Włodzimierz BednarskiAbstract:Candida Antarctica synthesised surface-active mannosylerythritol lipids at 46 g l−1 by adding 80 g soybean oil l−1 to the medium and maintaining the pO2 at 50% with an air flow rate 1 vvm. Two-stage culturing of C. Antarctica avoided medium foaming but the yield of biosurfactants synthesis was 28 g l−1. The biosurfactants decreased the surface tension of water to 35 mN m−1.
