title: Homogeneous enzymatic reactions in ionic liquids with poly(ethylene glycol)-modified subtilisin.
abstract: Subtilisin Carlsberg was covalently modified with comb-shaped poly(ethylene glycol) (PM13). PM13-modified subtilisin (PM13-Sub) was readily solubilized in three different ionic liquids (ILs), i.e., [Emim][Tf2N], [C2OC1mim][Tf2N] and [C2OHmim][Tf2N]. Analysis of homogeneous enzymatic reactions in the ILs revealed that PM13-Sub exhibited excellent catalytic performance while the native enzyme suspended in ILs showed no activity. Hydrophobicity of ILs slightly affected enzyme activity, and the relatively hydrophobic IL [Emim][Tf2N] was the preferred medium for enzymatic reactions, similar to enzymatic reactions in conventional organic solvents. Enzyme activity was much higher in [Emim][Tf2N] than in conventional organic solvents, and excellent activity was associated with unique properties of ILs such as hydrophobicity and high polarity. Furthermore, PM13-Sub showed good stability in [Emim][Tf2N], and maintained 80% of its initial activity after 60 h.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, and Center for Future Chemistry, Kyushu University, 744 Moto-oka, Fukuoka, 819-0395, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Nakashima
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Maruyama
authors.forename: Noriho
authors.initials: N
authors.lastname: Kamiya
authors.forename: Masahiro
authors.initials: M
authors.lastname: Goto
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology*; D002384:Catalysis; D004951:Esterification; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D052578:Ionic Liquids / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D012995:Solubility; D020860:Subtilisin / Q000737:chemistry / Q000378:metabolism*; D013816:Thermodynamics; D013997:Time Factors; D014867:Water / Q000378:metabolism
chemical_list: D052578:Ionic Liquids; D014867:Water; D011092:Polyethylene Glycols; D020860:Subtilisin