title: Lipase-catalyzed synthesis of fatty acid sugar ester using extremely supersaturated sugar solution in ionic liquids.
abstract: The low solubility of sugars has hampered the lipase-catalyzed synthesis of fatty acid sugar esters in organic solvents and ionic liquids (ILs), because several solvents that are able to effectively dissolve sugars are detrimental to enzymes. In this work, in order to prepare a high concentration of sugars in ILs, we have developed a new procedure that entails mixing an aqueous sugar solution into ILs followed by removal of the water from the solution. The glucose concentrations in the supersaturated [Emim][TfO] and [Bmim][TfO] were 19 and 10 times higher, respectively, than the solubilities (6.1 and 4.8 g/L) of glucose in the ILs at 25 degrees C. Furthermore, the supersaturated glucose solutions in ILs were maintained over a long period of time without any significant loss of glucose. In ILs that were extremely supersaturated with glucose, lipase-catalyzed esterifications of glucose with vinyl laurate, and lauric acid were successfully carried out. The conversion increased from 8% to 96% at 1 day of reaction by using supersaturated solution in [Bmim][TfO] which had dissolved glucose concentration of 400% higher than its solubility, compared with the reaction using saturated glucose solution. By making the glucose concentration in ILs much higher than the solubility through our novel and simple method, the initial rate and conversion of the lipase-catalyzed reaction were significantly improved.
authors.affiliation: ERC for Advanced Bioseparation Technology, Inha University, Incheon 402-751, Korea.
authors.forename: Sang Hyun
authors.initials: SH
authors.lastname: Lee
authors.forename: Dung Thanh
authors.initials: DT
authors.lastname: Dang
authors.forename: Sung Ho
authors.initials: SH
authors.lastname: Ha
authors.forename: Woo-Jin
authors.initials: WJ
authors.lastname: Chang
authors.forename: Yoon-Mo
authors.initials: YM
authors.lastname: Koo
mesh_terms: D002384:Catalysis; D004789:Enzyme Activation; D004800:Enzymes, Immobilized; D004951:Esterification; D004952:Esters / Q000138:chemical synthesis; D005227:Fatty Acids / Q000138:chemical synthesis*; D005656:Fungal Proteins; D005947:Glucose / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D008049:Lipase / Q000737:chemistry*; D012995:Solubility
chemical_list: D004800:Enzymes, Immobilized; D004952:Esters; D005227:Fatty Acids; D005656:Fungal Proteins; D052578:Ionic Liquids; C093667:Novozyme 435; D008049:Lipase; D005947:Glucose