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We developed a highly enantioselective separation system for the optically active compounds, (S)-ibuprofen and l-phenylalanine, from their racemic mixtures by employing a supported liquid membrane (SLM) encapsulating a surfactant-lipase complex (or a surfactant-alpha-chymotrypsin complex). In the present system, enzymes encapsulated in the liquid-membrane phase effectively drove the enantioselective transport of optically active compounds through the SLM. This novel SLM allowed high enantioselectivity (ee over 91%) in the optical resolution of racemic ibuprofen and phenylalanine.

Abstract: A new spectrophotometric assay has been developed to evaluate protease activity in ionic liquids (ILs). The assay consists of two strategies to enable real-time spectrometric analysis of enzymatic reaction in ILs. First, enzymes are modified with a comb-shaped poly(ethylene glycol), PM13, to obtain a transparent enzyme solution in IL. Second, a chromogenic substrate is used to follow the enzymatic reaction in IL. p-Nitroaniline-derivatized substrates are subjected to protease-catalyzed alcoholysis to release chromogenic p-nitroaniline that can be quantitatively detected by a UV–Vis spectrophotometer. By using this method, we can evaluate protease activity in ILs quite easily without separation of products from the reaction mixture. The availability of the novel assay system was demonstrated in a kinetic analysis of subtilisin-catalyzed reaction in the IL 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Emim][Tf2N]) under different reaction conditions. Because two different serine proteases, subtilisin and α-chymotrypsin, substantially retained its original substrate specificity in the IL, the assay can be extended to other enzymes by using suitable chromogenic substrates. [Copyright &y& Elsevier]

Abstract: Outstanding activation of an enzyme in ionic liquids (ILs) has been demonstrated by covalent modification with comb-shaped poly(ethylene glycol) (PEG) (PM13). Candida rugosa lipase modified with PM13 (PM13–CRL) was readily solubilized in all the ILs tested ([Emim][Tf2N], [C2OC1mim][Tf2N] and [C2OHmim][Tf2N]) containing 0.5% (v/v) of water, whereas native lipase did not dissolve in any of the ILs. The results for transesterification of 2-phenyl-1-propanol with vinyl acetate using lipase in ILs revealed that the PM13–CRL conjugate exhibits a high catalytic activity while suspended native lipase shows little activity. The hydrophobicity of ILs somewhat affected the enzyme activity and a more hydrophobic IL such as [Emim][Tf2N] was preferable for the lipase reaction, as was also observed in enzymatic reaction in conventional organic solvents. The enzyme activities in ILs were much higher than those in organic solvents, the excellent activity being associated with unique properties such as the hydrophobicity and the high polarity of ILs. Furthermore, the PM13-–CRL conjugate exhibited a high storage stability in [Emim][Tf2N]. [Copyright &y& Elsevier]

We have developed a lipase-facilitated supported liquid membrane. Lipase-catalyzed reactions were coupled with a supported liquid membrane (SLM) to transport organic acids through the SLM. We succeeded in the rational transport of organic acids through the SLM using lipase-catalyzed reactions and observed that there were differences in the transport behavior of various organic acids due to the substrate specificity of lipase. Subsequently, various parameters, such as the alcohol concentration in the feed phase, the pH in each aqueous phase, an organic solvent in the SLM, and the kind of lipase, were investigated. We found that the optimum conditions were 65 vol% alcohol concentration, pH 6.3 in each aqueous phase, isooctane as the liquid membrane phase and Candida rugosa lipase as the esterification biocatalyst. [Copyright &y& Elsevier]

A lipase-facilitated transport of 4-phenoxybutyric acid, 3-phenoxypropionic acid, 2-phenylpropionic acid, 2-phenoxybutyric acid, mandelic acid and 2-amino-2-phenylbutyric acid was carried out using a supported liquid membrane based on room temperature ionic liquids. There were marked differences in the permeate fluxes of various organic acids due to the substrate specificity of the lipases. The maximum permeate flux (44×10-2 mmol cm-2 × h) was obtained using 4-phenoxybutyric acid as the substrate and 1-n-butyl-3-methylimidazolium hexafluorophosphate as the liquid membrane phase. [ABSTRACT FROM AUTHOR]

We report a novel peptide–amphiphile having a simple molecular structure that can gelate an aqueous solution at a remarkably low concentration and can be designed to be responsive to a disease-related enzyme by undergoing a drastic morphological change. [ABSTRACT FROM AUTHOR]

Abstract: The degradation of the postharvest fungicide imazalil by the oxidative enzyme laccase was investigated in the presence of a reaction mediator (a laccase/mediator system). Of various natural mediators tested, imazalil was degraded most effectively in the presence of 4-hydroxybenzoic acid while the absence of a mediator resulted in no degradation. In this system, the mediator compound was oxidized by laccase and then the oxidized mediator oxidized imazalil. The study on the cytotoxicity of the degraded-imazalil solution against mouse fibroblast L929 cells revealed toxicity of 4-hydroxybenzoic acid. The cytotoxic study also suggested that instead of 4-hydroxybenzoic acid, the used of methyl 4-hydroxybenzoate as the reaction mediator reduced the intrinsic cytotoxicity of imazalil. [Copyright &y& Elsevier]

The water content of a water-immiscible can be controlled using reverse micelles. We applied this reverse micellar system to improve the enzymatic activity of a surfactant-manganese peroxidase complex in toluene. Increasing the water content in toluene to 2 vol% using the reverse micelles resulted in the great improvement (10-fold) of the peroxidase activity. [Copyright &y& Elsevier]