Enzymatic preparation of enantiomerically pure sn-2,3-diacylglycerols: A stereoselective ethanolysis approach |
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Authors: | Weera Piyatheerawong Tsuneo Yamane Hideo Nakano Yugo Iwasaki |
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Affiliation: | (1) Laboratory of Molecular Biotechnology, Graduate School of Biogricultural Sciences, Nagoya University, Furocho, Chikusa-ku, 464-8601 Nagoya, Japan;(2) Department of Environmental Biology, School of Bioscience and Biotechnology, Chubu University, 487-8501 Aichi, Japan |
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Abstract: | Stereoselective ethanolysis of monoacid TAG by immobilized Rhizomucor miehei lipase (RML) was studied for preparation of optically pure sn-2,3-DAG. Trioctanoylglycerol (TO) was used as a model substrate. The enantiomeric purity of the product, sn-2,3-dioctanoylglycerol (sn-2,3-DO), was very high (percent enantiomeric excess >99%) when an excess of ethanol was used. The result indicated that RML
was highly stereoselective toward the sn-1 position of TO under conditions of excess ethanol. The stereoselectivity of RML depended on the amount of ethanol. The
larger the amount of ethanol was, the higher the stereoselectivity became. After optimizing the parameters such as reactant
molar ratio, water content, and temperature, (ethanol/TO molar ratio =31∶1 and water content =7.5 wt% of the reactants at
25°C), optically pure sn-2,3-DO was obtained at 61.1 mol% in the glyceride fraction in 20 min. The above conditions were further applied for ethanolysis
of monoacid TAG with different acyl groups such as tridecanoylglycerol (C10∶0), tridodecanoylglycerol (C12∶0), tritetradecanoylglycerol
(C14∶0) and trioctadecenoylglycerol triolein, (C18∶1)]. The yields and enantiomeric purities of 1,2(2,3)-DAG were dramatically
reduced when TAG with FA longer than decanoic acid were used. |
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Keywords: | sn-2 3-Diacylglycerols ethanolysis monoacid triacylglycerols Rhizomucor miehei lipase |
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