α‐Chymotrypsin catalysis in imidazolium‐based ionic liquids

Abstract

The transesterification reaction of N-acetyl-L-phenylalanine ethyl ester with 1-propanol catalyzed by alpha-chymotrypsin was examined in the ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]) and 1-octyl-3-methylimidazolium hexafluorophosphate ([omim][PF(6)]), and in combination with supercritical carbon dioxide (SC-CO(2)). The activity of alpha-chymotrypsin was studied to determine whether trends in solvent polarity, water activity, and enzyme support properties, observed with this enzyme in conventional organic solvents, hold for the novel environment provided by ionic liquids. alpha-Chymotrypsin freeze-dried with K(2)HPO(4), KCl, or poly(ethylene glycol) demonstrated no activity in [bmim][PF(6)] or [omim][PF(6)] at very low water concentrations, but moderate transesterification rates were observed with the ionic liquids containing 0.25% water (v/v) and higher. However, the physical complexation of the enzyme with poly(ethylene glycol) or KCl did not substantially stimulate activity in the ionic liquids, unlike that observed in hexane or isooctane. Activities were considerably higher in [omim][PF(6)] than [bmim][PF(6)]. Added water was not necessary for enzyme activity when ionic liquids were combined with SC-CO(2). These results indicate that [bmim][PF(6)] and [omim][PF(6)] provide a relatively polar environment, which can be modified with nonpolar SC-CO(2) to optimize enzyme activity.

Voltammetric Behavior of Bilirubin Based on [bmim][PF6] As the Supporting Electrolyte in Organic Solvent and Its Analytical Application

“…In this paper, a hydrophobic IL- [Bmim][PF 6 ] was prepared as described in the literature [20]. The purity of IL was checked by elemental analysis and 1 HNMR and 13 CNMR spectroscopy, and the residual water content was analyzed by standard Karl-Fisher titration to be below 0.07% (w/w).…”

Activation of lipase in ionic liquids by modification with comb-shaped poly(ethylene glycol)

“…Although adding a small amount of water improves the solubility of enzymes, excessive addition of water would lead to a decline in enzyme activity [15]. Altering the chemical structure of ILs is a promising and effective way of solubilizing enzymes, however, this often causes inactivation of the enzyme [21].…”

“…Since the pioneering studies by some groups [8][9][10], many biocatalytic reactions in ILs have been actively conducted with lipases [11][12][13][14], proteases [15,16], oxidoreductases [17,18], and even with a whole-cell biocatalyst [19]. When compared to reactions performed in conventional organic solvents, ILs provide a more suitable environment for enzymes [16,20] and are obviously less harmful to cell membranes [19], resulting in high catalytic performance.…”

Spectroscopic evaluation of chiral and achiral fluorescent ionic liquids

“…For instance, conventional organic solvents have been replaced by ILs in organic synthesis [9]. They have also been used in solvent extractions [10], liquid-liquid extractions [11], enzymatic reactions [12], pharmaceutical studies [13], electrochemical studies [14], dye-sensitized solar cells and batteries [15], and as buffer additives in capillary electrophoresis [16], stationary phases in gas-liquid chromatography [17], and ultralow volatility liquid matrixes for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry [18]. In addition, their high thermal stability allows for their use in high temperature gas sensing [19].…”