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Mohamed Ghoul - One of the best experts on this subject based on the ideXlab platform.
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effect of Acyl Donor chain length and sugar Acyl Donor molar ratio on enzymatic synthesis of fatty acid fructose esters
Journal of Molecular Catalysis B-enzymatic, 2001Co-Authors: Samia Soultani, Jeanmarc Engasser, Mohamed GhoulAbstract:Abstract Lipase-catalyzed synthesis of fatty acid sugar esters through direct esterification was performed in 2-methyl 2-butanol as solvent. Fructose and saturated fatty acids were used as substrates and the reaction was catalyzed by immobilized Candida antarctica lipase. The effect of the initial fructose/Acyl Donor molar ratio and the carbon-chain length of the Acyl Donor as well as their reciprocal interactions on the reaction performance were investigated. For this purpose, an experimental design taking into account variations of the molar ratio (from 1:1 to 1:5) and the carbon-chain length of the fatty acid (from C8 to C18) was employed. Statistical analysis of the data indicated that the two factors as well as their interactions had significant effects on the sugar esters synthesis. The obtained results showed that whatever the molar ratio used, the highest concentration (73 g l−1), fructose and fatty acid conversion yields (100% and 80%, respectively) and initial reaction rate (40 g l−1 h−1) were reached when using the C18 fatty acid as Acyl Donor. Low molar ratios gave the best fatty acid conversion yields and initial reaction rates, whereas the best total sugar ester concentrations and fructose conversion yields were obtained for high molar ratios.
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Effect of Acyl Donor chain length and sugar/Acyl Donor molar ratio on enzymatic synthesis of fatty acid fructose esters
Journal of Molecular Catalysis B-enzymatic, 2001Co-Authors: Samia Soultani, Jeanmarc Engasser, Mohamed GhoulAbstract:Abstract Lipase-catalyzed synthesis of fatty acid sugar esters through direct esterification was performed in 2-methyl 2-butanol as solvent. Fructose and saturated fatty acids were used as substrates and the reaction was catalyzed by immobilized Candida antarctica lipase. The effect of the initial fructose/Acyl Donor molar ratio and the carbon-chain length of the Acyl Donor as well as their reciprocal interactions on the reaction performance were investigated. For this purpose, an experimental design taking into account variations of the molar ratio (from 1:1 to 1:5) and the carbon-chain length of the fatty acid (from C8 to C18) was employed. Statistical analysis of the data indicated that the two factors as well as their interactions had significant effects on the sugar esters synthesis. The obtained results showed that whatever the molar ratio used, the highest concentration (73 g l−1), fructose and fatty acid conversion yields (100% and 80%, respectively) and initial reaction rate (40 g l−1 h−1) were reached when using the C18 fatty acid as Acyl Donor. Low molar ratios gave the best fatty acid conversion yields and initial reaction rates, whereas the best total sugar ester concentrations and fructose conversion yields were obtained for high molar ratios.
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Enzymic synthesis of fructose monooleate in a reduced pressure pilot scale reactor using various Acyl Donors
Process Biochemistry, 1999Co-Authors: Denis Coulon, Michel Girardin, Mohamed GhoulAbstract:Enzymic synthesis of fructose esters was studied under reduced pressure. Different Acyl Donors were tested, and immobilized Candida antarctica lipase was used as biocatalyst. Influences of pressure, nature of the Acyl Donor, molar ratio sugar/Acyl Donor were investigated. Pressure had the greatest influence. At 200 mbar, more than 90% of fructose was Acylated compared to 50% under atmospheric pressure. This is explained by the evaporation of reaction by-product (methanol or water) that shifted the equilibrium. C. antarctica lipase catalyzed sugar ester synthesis very efficiently using rapeseed oil as Acyl Donor. Moreover, synthesis performed with an equimolar mixture of both substrates gave promising results. Although the reaction rate was slower than synthesis performed with an excess of fatty acid, fructose monooleate concentration was still high (44 g l−1 instead of 56 g l−1) and the residual Acyl Donor concentration was very low. Downstream processes for the recovery of pure fructose monooleate were simplified in this case.
Paul J Pachlatko - One of the best experts on this subject based on the ideXlab platform.
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esterification of streptol a cyclitol derivative by candida rugosa lipase influence of the Acyl Donor on regioselectivity
Journal of Molecular Catalysis B-enzymatic, 2005Co-Authors: Wolfgang Kroutil, Leonhard Hagmann, Traugott Christoph Schuez, Volker Jungmann, Paul J PachlatkoAbstract:Abstract The influence of the nature of Acyl Donors on the regioselectivity of Candida rugosa lipase for the esterification of streptol — a cyclitol derivative — was investigated. Excellent regioselectivity for the formation of 3,7-disubstituted derivatives was observed for vinyl butyrate (100% 3,7-derivative, 68% yield) and vinyl propionate (100% 3,7-derivative, 46% yield) as Acyl Donors. In contrast, for vinyl methacrylate as Acyl Donor, a mixture of 71% 3,7-derivative and 29% 1,7-derivative was obtained. Varying the chain length, a certain dependency of regioselectivity on the Acyl Donor was observed, however, no logical correlation satisfying all cases was found. Mono-substituted streptol derivatives were obtained by employing Novozym 243.
Wolfgang Kroutil - One of the best experts on this subject based on the ideXlab platform.
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esterification of streptol a cyclitol derivative by candida rugosa lipase influence of the Acyl Donor on regioselectivity
Journal of Molecular Catalysis B-enzymatic, 2005Co-Authors: Wolfgang Kroutil, Leonhard Hagmann, Traugott Christoph Schuez, Volker Jungmann, Paul J PachlatkoAbstract:Abstract The influence of the nature of Acyl Donors on the regioselectivity of Candida rugosa lipase for the esterification of streptol — a cyclitol derivative — was investigated. Excellent regioselectivity for the formation of 3,7-disubstituted derivatives was observed for vinyl butyrate (100% 3,7-derivative, 68% yield) and vinyl propionate (100% 3,7-derivative, 46% yield) as Acyl Donors. In contrast, for vinyl methacrylate as Acyl Donor, a mixture of 71% 3,7-derivative and 29% 1,7-derivative was obtained. Varying the chain length, a certain dependency of regioselectivity on the Acyl Donor was observed, however, no logical correlation satisfying all cases was found. Mono-substituted streptol derivatives were obtained by employing Novozym 243.
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Esterification of streptol — a cyclitol derivative — by Candida rugosa lipase: influence of the Acyl Donor on regioselectivity
Journal of Molecular Catalysis B-enzymatic, 2005Co-Authors: Wolfgang Kroutil, Leonhard Hagmann, Traugott Christoph Schuez, Volker Jungmann, J. Paul PachlatkoAbstract:Abstract The influence of the nature of Acyl Donors on the regioselectivity of Candida rugosa lipase for the esterification of streptol — a cyclitol derivative — was investigated. Excellent regioselectivity for the formation of 3,7-disubstituted derivatives was observed for vinyl butyrate (100% 3,7-derivative, 68% yield) and vinyl propionate (100% 3,7-derivative, 46% yield) as Acyl Donors. In contrast, for vinyl methacrylate as Acyl Donor, a mixture of 71% 3,7-derivative and 29% 1,7-derivative was obtained. Varying the chain length, a certain dependency of regioselectivity on the Acyl Donor was observed, however, no logical correlation satisfying all cases was found. Mono-substituted streptol derivatives were obtained by employing Novozym 243.
Samia Soultani - One of the best experts on this subject based on the ideXlab platform.
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effect of Acyl Donor chain length and sugar Acyl Donor molar ratio on enzymatic synthesis of fatty acid fructose esters
Journal of Molecular Catalysis B-enzymatic, 2001Co-Authors: Samia Soultani, Jeanmarc Engasser, Mohamed GhoulAbstract:Abstract Lipase-catalyzed synthesis of fatty acid sugar esters through direct esterification was performed in 2-methyl 2-butanol as solvent. Fructose and saturated fatty acids were used as substrates and the reaction was catalyzed by immobilized Candida antarctica lipase. The effect of the initial fructose/Acyl Donor molar ratio and the carbon-chain length of the Acyl Donor as well as their reciprocal interactions on the reaction performance were investigated. For this purpose, an experimental design taking into account variations of the molar ratio (from 1:1 to 1:5) and the carbon-chain length of the fatty acid (from C8 to C18) was employed. Statistical analysis of the data indicated that the two factors as well as their interactions had significant effects on the sugar esters synthesis. The obtained results showed that whatever the molar ratio used, the highest concentration (73 g l−1), fructose and fatty acid conversion yields (100% and 80%, respectively) and initial reaction rate (40 g l−1 h−1) were reached when using the C18 fatty acid as Acyl Donor. Low molar ratios gave the best fatty acid conversion yields and initial reaction rates, whereas the best total sugar ester concentrations and fructose conversion yields were obtained for high molar ratios.
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Effect of Acyl Donor chain length and sugar/Acyl Donor molar ratio on enzymatic synthesis of fatty acid fructose esters
Journal of Molecular Catalysis B-enzymatic, 2001Co-Authors: Samia Soultani, Jeanmarc Engasser, Mohamed GhoulAbstract:Abstract Lipase-catalyzed synthesis of fatty acid sugar esters through direct esterification was performed in 2-methyl 2-butanol as solvent. Fructose and saturated fatty acids were used as substrates and the reaction was catalyzed by immobilized Candida antarctica lipase. The effect of the initial fructose/Acyl Donor molar ratio and the carbon-chain length of the Acyl Donor as well as their reciprocal interactions on the reaction performance were investigated. For this purpose, an experimental design taking into account variations of the molar ratio (from 1:1 to 1:5) and the carbon-chain length of the fatty acid (from C8 to C18) was employed. Statistical analysis of the data indicated that the two factors as well as their interactions had significant effects on the sugar esters synthesis. The obtained results showed that whatever the molar ratio used, the highest concentration (73 g l−1), fructose and fatty acid conversion yields (100% and 80%, respectively) and initial reaction rate (40 g l−1 h−1) were reached when using the C18 fatty acid as Acyl Donor. Low molar ratios gave the best fatty acid conversion yields and initial reaction rates, whereas the best total sugar ester concentrations and fructose conversion yields were obtained for high molar ratios.
Samuel J Danishefsky - One of the best experts on this subject based on the ideXlab platform.
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toward homogeneous erythropoietin fine tuning of the c terminal Acyl Donor in the chemical synthesis of the cys29 gly77 glycopeptide domain
Journal of the American Chemical Society, 2009Co-Authors: Yu Yua, Ji Che, Gong Che, Samuel J DanishefskyAbstract:Described herein is the chemical synthesis of the Cys29−Gly77 glycopeptide domain (22) of erythropoietin. Our initial ligation strategy targeted a C → N termini condensation between glycopeptide 3 and peptide 4. However, the reaction was hindered by the “unattainable” reactivity, mismatched polarity, and severe aggregation of the (glyco)peptide substrates. In contrast, by tuning the C-terminal Acyl Donor and using smaller peptide fragments, the Cys29−Gly77 glycopeptide domain of erythropoietin was prepared through unconventional N → C termini condensation reactions. The use of a p-cyanonitrophenyl ester and the development of a masked thiophenyl ester as Acyl Donors enabled us to promptly access glycopeptides bearing complex carbohydrates and offer potential synthetic applications beyond our current work.
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Toward Homogeneous Erythropoietin: Fine Tuning of the C-Terminal Acyl Donor in the Chemical Synthesis of the Cys29−Gly77 Glycopeptide Domain
Journal of the American Chemical Society, 2009Co-Authors: Yu Yuan, Jin Chen, Qian Wan, Zhongping Tan, Gong Chen, Cindy Kan, Samuel J DanishefskyAbstract:Described herein is the chemical synthesis of the Cys29−Gly77 glycopeptide domain (22) of erythropoietin. Our initial ligation strategy targeted a C → N termini condensation between glycopeptide 3 and peptide 4. However, the reaction was hindered by the “unattainable” reactivity, mismatched polarity, and severe aggregation of the (glyco)peptide substrates. In contrast, by tuning the C-terminal Acyl Donor and using smaller peptide fragments, the Cys29−Gly77 glycopeptide domain of erythropoietin was prepared through unconventional N → C termini condensation reactions. The use of a p-cyanonitrophenyl ester and the development of a masked thiophenyl ester as Acyl Donors enabled us to promptly access glycopeptides bearing complex carbohydrates and offer potential synthetic applications beyond our current work.
