title: Thermodynamically based solvent design for enzymatic saccharide acylation with hydroxycinnamic acids in non-conventional media.
abstract: Enzyme-catalyzed synthesis has been widely studied with lipases (EC 3.1.1.3), but feruloyl esterases (FAEs; EC 3.1.1.73) may provide advantages such as higher substrate affinity and regioselectivity in the synthesis of hydroxycinnamate saccharide esters. These compounds are interesting because of their amphiphilicity and antioxidative potential. Synthetic reactions using mono- or disaccharides as one of the substrates may moreover direct new routes for biomass upgrading in the biorefinery. The paper reviews the available data for enzymatic hydroxycinnamate saccharide ester synthesis in organic solvent systems as well as other enzymatic hydroxycinnamate acylations in ionic liquid systems. The choice of solvent system is highly decisive for enzyme stability, selectivity, and reaction yields in these synthesis reactions. To increase the understanding of the reaction environment and to facilitate solvent screening as a crucial part of the reaction design, the review explores the use of activity coefficient models for describing these systems and - more importantly - the use of group contribution model UNIFAC and quantum chemistry based COSMO-RS for thermodynamic predictions and preliminary solvent screening. Surfactant-free microemulsions of a hydrocarbon, a polar alcohol, and water are interesting solvent systems because they accommodate different substrate and product solubilities and maintain enzyme stability. Ionic liquids may provide advantages as solvents in terms of increased substrate and product solubility, higher reactivity and selectivity, as well as tunable physicochemical properties, but their design should be carefully considered in relation to enzyme stability. The treatise shows that thermodynamic modeling tools for solvent design provide a new toolbox to design enzyme-catalyzed synthetic reactions from biomass sources.
authors.affiliation: Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Building 229, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Birgitte
authors.initials: B
authors.lastname: Zeuner
authors.forename: Georgios M
authors.initials: GM
authors.lastname: Kontogeorgis
authors.forename: Anders
authors.initials: A
authors.lastname: Riisager
authors.forename: Anne S
authors.initials: AS
authors.lastname: Meyer
mesh_terms: D000215:Acylation; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry*; D003373:Coumaric Acids / Q000737:chemistry*; D004187:Disaccharides / Q000737:chemistry*; D004795:Enzyme Stability; D008956:Models, Chemical; D009005:Monosaccharides / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D003373:Coumaric Acids; D004187:Disaccharides; D009005:Monosaccharides; D012997:Solvents; D002265:Carboxylic Ester Hydrolases; C070196:feruloyl esterase