Ionic Liquid-Mediated Activation of Lipase-Catalysed Reaction

Ionic Liquids as Tool to Improve Enzymatic Organic Synthesis

“…Investigations of lipase-catalyzed reactions using ILs as reaction media thus began in 2000 and 2001. Since then, numerous types of ILs have been developed as solvents for lipase-catalyzed reactions. − Lozano and co-workers reported that stability of lipases was also significantly enhanced by the ILs. , Itoh et al also reported that remarkably increased stability of CAL in [C 4 mim]­[BF 4 ] was observed, and they accomplished recyclable use of the enzyme in transesterification of 10 times while maintaining excellent enantioselectivity in this IL as a solvent . Gubicza and co-workers reported similar favorable results of ILs as solvents in the transesterification of secondary alcohols, though both the water contents in ILs and IL species strongly influenced the enzyme activity. , Rezac et al also reported water effect on the CAL-catalyzed esterification of geraniol with acetic acid in [C 4 mim]­[PF 6 ] and determined an optimal water level near aw = 0.6 .…”

“…178 In my own experiments, neither thermolysin nor α-chymotrypsin was active in a pure IL solvent. 48 Therefore, except for lipases, very careful optimization of water content is apparently required to realize desired reactions.…”

“…The microbes are stable in the presence of 80% (v/v) ILs, [C 2 mim]­[TsO], [C 4 mim]­[Cl], [C 4 mim]­[TFA], [C 4 mim]­[BF 4 ], [C 4 mim]­[PF 6 ], or [C 4 mim]­[Tf 2 N], and the enzyme exhibited activity in a buffer solution in the presence of 10% (v./v) of these ILs . In my own experiments, neither thermolysin nor α-chymotrypsin was active in a pure IL solvent . Therefore, except for lipases, very careful optimization of water content is apparently required to realize desired reactions.…”

“…The first three examples were reported in this field in 2000, − and since then, a large number of applications have been reported for biocatalytic reactions in ILs. Good many reviews from various standpoints in this field have been published. − Furthermore, two reviews focusing on the topic of enhanced stability of peptides in ILs have been published: several ammonium type ILs have biocompatibility and can stabilize some proteins or even a DNA. , Therefore, in this review, I have focused on mainly two topics using ILs for enzymatic reactions from the standpoint of biocatalyst mediating organic synthesis: the first is “Biocatalysis in ILs” which consists of various types of biocatalytic reactions in ILs, and the second: “Enzymes Activated by ILs for Organic Synthesis”, in particular, “activation of lipase-catalyzed reactions using IL engineering”, I also discuss in what fields we should focus our investigation for utilizing ILs in biotechnology in the future.…”