Enzymes in Nearly Anhydrous Ionic Liquids

Whole Free enzyme Dissolved Suspension Dissolved cells (dissolved in H20) Enzyme (whole cells) enzyme 

Other microbial lipases have also been successfully used in anhydrous ionic liquids, e.g., from Alcaligenes sp. (AsL) [54, 58], CaLA, Rhizomucor miehei lipase (RmL), and Thermomyces lanuginosus lipase (TIL) [54]. The lipase from pig pancreas (porcine pancreas lipase, PPL), the only mammalian lipase that has been subjected to ionic liquids, catalyzed transesterificationin[BMIm][NTf2]butnotin[BMIm][PF6] 

Esterases are much less tolerant of anhydrous media than lipases. The esterases from Bacillus stearothermophilus (BstE) and Bacillus subtilis (BsE) are exceptional, as these mediated transesterification in hexane at aw=0.1 [66]. Both esterases, if immobilized on Celite 560, mediated transesterification in [BMIm][BF4], [BMIm][PF6], and [BMIm][ Tf2N] at a rate that varied from 20 to 60% of the rate in hexane or ME. 

Proteases have also been successfully used in ionic liquids. Papain mediated the enantioselective hydrolysis of a number of amino acid esters in an 80 20 mixture of [BMIm][BF4] and water [68]. The reaction rate was approx. 50% of that in aqueous buffer and equal to that in aqueous mixtures containing 70- 80% of solvents such as acetonitrile or tert-butyl alcohol. 

Subtilisin generally shows poor transesterification activity in water-free ionic liquids, but Shah and Gupta [73] studied various approaches to maintaining its activity. The best results-up to 10000 times increase in the initial rate N-acetyl-phenylalanine ethyl ester in [BMIm] [PF6]-were obtained by precipitating and washing with 1-propanol. 

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Stability of Enzymes in Nearly Anhydrous Ionic Liquids 235... 

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