A new microheterogeneous non-aqueous medium for enzymatic reactions, based on reversed micelles of a polymeric surfactant, was suggested. The surfactant termed CEPEI, was synthesized by successive alkylation of poly(ethy1eneimine) with cetyl bromide and ethyl bromide and was found to be able to solubilize considerable amounts of water in benzeneln-butanol mixtures. The hydrodynamic radius of polymeric-reversed micelles was estimated to be in the range 22 -51 nm, depending on the water content of the system, as determined by means of the quasi-elastic laser-light scattering. Polymeric reversed micelles were capable of solubilizing enzymes (a-chymotrypsin and laccase) in nonpolar solvents with retention of catalytic activity. Due to the strong buffering properties of CEPEI over a wide pH range, it could maintain any adjusted pH inside hydrated reversed micelles. It was found that catalytic behavior of enzymes entrapped in polymeric reversed micelles was rather insensitive to the pH of the buffer solution introduced into the system as an aqueous component, but determined mostly by acid-base properties of the polymeric surfactant itself. Both catalytic activity and stability of entrapped a-chymotrypsin and laccase were found to increase with increasing water content of the system. Under certain conditions, the entrapment of a-chymotrypsin into CEPEI reversed micelles resulted in a considerable increase in catalytic activity and stability as compared to aqueous solution. CEPEI reversed micelles were demonstrated to be promising enzyme carriers for use in membrane reactors. Owing to the large dimensions of CEPEI reversed micelles, they are effectively kept back by a semipermeable membrane, thus allowing an easy separation of the reaction product and convenient recovery of the enzyme.Biocatalytic systems in organic solvents with low water content have attracted much interest during the last decade [l, 21. This interest is due to the fact that the use of nonaqueous biocatalytic systems allows one to solve a number of important problems often encountered in synthetic enzymology, such as the conversion of water-insoluble substrates and favorable shifts of reaction equilibria, etc. Surfactant reversed micelles in nonpolar organic solvents, which contain entrapped enzymes [l, 21, belong to the most promising nonaqueous biocatalytic systems owing to their essential advantages, such as versatility (to date several enzymes have been shown to retain catalytic activity in reversed micelles), almost complete absence of diffusion limitations, optical transparency and ease of preparation. However, from the practical point of view, reversed micellar systems suffer from a serious drawback connected with the presence of high concentrations of low-molecular-mass surfactants, which makes the problem of reactionproduct separation and enzyme recovery very difficult. This drawback can be eliminated by the use of polymeric reversed (EC 1.10.3.2); wchymotrypsin (EC 3.4.21.1). micelles which, being large and practically non-dissociating e...
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