title: Enzyme-Catalyzed Henry Reaction in Choline Chloride-Based Deep Eutectic Solvents.
abstract: The enzyme-catalyzed Henry reaction was realized using deep eutectic solvents (DESs) as a reaction medium. The lipase from Aspergillus niger (lipase AS) showed excellent catalytic activity toward the substrates aromatic aldehydes and nitromethane in choline chloride:glycerol at a molar ratio of 1:2. Addition of 30 vol% water to DES further improved the lipase activity and inhibited DES-catalyzed transformation. A final yield of 92.2% for the lipase AS-catalyzed Henry reaction was achieved under optimized reaction conditions in only 4 h. In addition, the lipase AS activity was improved by approximately 3-fold in a DES-water mixture compared with that in pure water, which produced a final yield of only 33.4%. Structural studies with fluorescence spectroscopy showed that the established strong hydrogen bonds between DES and water may be the main driving force that affects the spatial conformation of the enzyme, leading to a change in lipase activity. The methodology was also extended to the aza-Henry reaction, which easily occurred in contrast to that in pure water. The enantioselectivity of both Henry and aza-Henry reactions was not found. However, the results are still remarkable, as we report the first use of DES as a reaction medium in a lipase-catalyzed Henry reaction.
authors.affiliation: College of Life Sciences, Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, Jilin University, Changchun 130012, P.R. China.|College of Chemistry, Jilin University, Changchun 130012, P.R. China.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Tian
authors.affiliation: College of Chemistry, Jilin University, Changchun 130012, P.R. China.
authors.forename: Suoqin
authors.initials: S
authors.lastname: Zhang
authors.affiliation: College of Life Sciences, Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, Jilin University, Changchun 130012, P.R. China.
authors.forename: Liangyu
authors.initials: L
authors.lastname: Zheng
mesh_terms: D001234:Aspergillus niger / Q000737:chemistry / Q000201:enzymology*; D055162:Biocatalysis; D002794:Choline / Q000737:chemistry*; D005656:Fungal Proteins / Q000737:chemistry*; D007536:Isomerism; D008049:Lipase / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry
chemical_list: D005656:Fungal Proteins; D012997:Solvents; D008049:Lipase; D002794:Choline
keywords: Deep eutectic solvents; Henry reaction; Lipase AS