| Summary: | 碩士 === 國立中興大學 === 化學系 === 87 === Abstract
Enzyme immobilization has become an increasingly important technique in applications of biochemical engineering, food industry and medicinal fields. After immobilization, however, the interactions of enzymes with their substrates frequently altered and, consequently, the enzymatic activities also changed. In this study, it is intended to investigate the enzymatic activity of the enzyme after immobilization toward high and low molecular weight substrates. Poly(N-isopropylacrylamide) was used for conjugation with chymotrypsin to various extents as a temperature-sensitive immobilized enzyme system. N-CBZ-Gly-Gly-Phe-NAp, N-benzoyl-L-Tyr-NAp and N-succinyl-L-Phe-NAp were used as low molecular weight substrates whereas bovine serum albumins modified with poly(ethylene glycol) and poly(N-isopropylacrylamide) were exploited as high molecular weight substrates. The kinetic results indicate that low molecular weight substrates were degraded faster by the immobilized enzyme than the native chymotrypsin. The cleavage rate of bovine serum albumin was reduced by the chemical conjugation of the substrate and the enzyme with poly(N-isopropylacrylamide) or poly(ethylene glycol). The reduction in BSA cleavage was strongly dependent upon the extent of conjugation and the molecular weight of the polymer. In addition, it is generally observed that the degradation of bovine serum albumin by the modified and native enzyme was faster at 37℃ than at 25℃.
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