We have applied the newly developed method of preparing surfactant-enzyme complexes to other different enzyme sources in order to study the efficacy of this technique in the catalyzed transesterification processes. Protease from varied material sources was modified with surfactant molecules utilizing water-in-oil (W/O) emulsions, and the complex so formed proved very effective in catalyzing vinyl butyrate transesterification with benzyl alcohol in organic media. By contrast, native commercial protease and a lyophilized protease from optimum buffer solution pH hardly catalyzed the above process. Although, conventionally prepared surfactant, coated protease had shown some catalytic activity, its performance was significantly lower than that of the surfactant-protease complex assembled in the novel preparation method. The typical transesterification rates catalytically induced by surfactant-protease complexes were in the range of 7-260-fold superior relative to other catalyzed reaction systems. The preparation and reaction conditions of the surfactant-protease P (Aspergillus melleus) have been optimized through studies of the effect of aqueous pH in the W/O emulsions, the nature of the organic solvents and surfactants, and the reaction temperature. The protease complex prepared from nonionic surfactant 2C18Δ9GE at optimized aqueous pH yielded the best results in isooctane at 45 °C. This novel enzyme modification method is conceptually simple, and the resultant complexes are elucidable. It is hoped that this method will become useful, particularly in preparing enzymes that are nonaqueous media sensitive and soluble in organic solution.
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