Immobilization of Esterase on Chitosan

• Main Authors: Shih-Yung Ho, 何世湧
• Other Authors: Shyh-Yu Shaw
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/64528763217621462334

碩士 === 國立成功大學 === 化學系碩博士班 === 91 === 　　In this paper, a stereoselective esterase cloned from Pseudomonas putida was expressed in E.coli and used for optical resolution of methyl DL-β-acetylthioisobutyrate ( MATI ) to get D-β-acetylthioisobutyric acid (DAT). DAT is a precursor of an antihypertensive drug ---Captopril. 　　In order to reuse and increase the stability of esterase. In this study,esterase from pseudomonas putida was immobilized onto chitosan film using glutaraldehyde (1%,w/v) as cross-linking reagent. Esterase was immobilized on the chitosan film that is a natural polymer. The studies were done on free esterase and immobilized esterase on chitosan film to determine the kinetic parameters, optimum temperature, optimum pH, thermal stability,storage stability, and operational stability. 　　The result showed that optimum temperature for free esterase and immobilized esterase on chitosan film is 67°C.Optimum pH is 7.5 , 8.5 for free esterase and immobilized esterase respectively.It was found that KM =26.1 mM，Vmax=833.0 μmol/min•mg protein for free esterase and KM =197.8 mM，Vmax=3.6 μmol/min•mg protein for immobilized esterase on chitosan. The kinetic parameters of the immobilized esterase were significantly changed but the thermal and pH stabilities of the immobilized esterase were improved.