Effect of silicon atom in substrate on transcyanation of aliphatic ketones with acetone cyanohydrin catalyzed by (R)-oxynitrilase from apple seed meal

ORGN 660

Jun He, cindy_he@tom.com1, Min-hua Zong, btmhzong@scut.edu.cn1, and Hong Wu, bbhwu@scut.edu.cn2. (1) Department of Biotechnology, South China University of Technology, 1 Wushan Street, Guangzhou, 510640, China, (2) College of Biological Sciences and Biotechnology, South China University of Technology, 1 Wushan Street, Guangzhou, 510640, China
The transformation of prochiral acetyltrimethylsilane and its carbon analogue 3,3-dimethyl-2-butanone to corresponding cyanohydrins catalyzed by (R)-oxynitrilase from apple seed meal in a biphasic system of citrate buffer and organic solvent has been comparatively investigated under different conditions of organic solvent, volume ratio of water to organic solvent, apple seed meal concentration, substrate concentration, buffer pH and reaction temperature. It has been found that within the range examined, the initial reaction rate, the substrate conversion and the product e.e. of the reaction with acetyltrimethylsilane being the substrate are all much higher than those when 3,3-dimethyl-2-butanone are used as the substrate, indicating the improvement of the reaction by the silicon atom. The significance of silicon effect on the reaction, however, depends on the reaction conditions. Kinetic study has shown higher affinity of the enzyme towards acetyltrimethylsilane(with Km being 13.28 mM) than its carbon counterpart(with Km being 103.95 mM).
 

Asymmetric Reactions, Heterocycles, Aromatics, Combinatorial, and Physical Organic Chemistry
8:00 PM-10:00 PM, Wednesday, 31 August 2005 Washington DC Convention Center -- Hall A, Poster

Sci-Mix
8:00 PM-10:00 PM, Monday, 29 August 2005 Washington DC Convention Center -- Hall A, Sci-Mix

Division of Organic Chemistry

The 230th ACS National Meeting, in Washington, DC, Aug 28-Sept 1, 2005