Engineering of Thermostable Phytase by Fusing Sso7d, a Hyperthermophilic Protein, to the N-Terminus of Phytase: Analysis of Sso7d-Phytase Thermostability

• Main Authors: Yi Wen, 文彝
• Other Authors: Andrew H. -J. Wang
• Format: Others
• Language: en_US
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/49515599246518331302

碩士 === 國立臺灣大學 === 生化科學研究所 === 92 === The thermostability of protein is an interesting topic of the research in protein science. Thermostable enzyme especially has broad applications in industry. Numerous attempts have been done to improve protein thermostability. In this thesis, a novel strategy to engineer thermostable enzyme was proposed. Sso7d, a thermostable protein with potential chaperone function was linked to the N-terminus of phytase, a specific phosphotase of great importance in animal food industry. Series of trials has been done to get soluble Sso7d-phytase fusion protein. At last four kinds of Sso7d-phytase with different linker-length were obtained. Activity assay and CD spectroscopy were employed to analyze the thermostablity of Sso7d-phytase. The results of activity assay showed that fusion with Sso7d does not affect the optimal catalytic temperature of phytase, but slightly enhances the heat tolerance. On the other hand, the CD data demonstrated that Sso7d-fusion helps the refolding of phytase after thermal denaturation. The degree of renaturation elevates with the shortening of flexible linkage and the presence of ATP/Mg2+. The study suggests that Sso7d has the chaperone ability and fusion with Sso7d is a practical way to engineer thermostable protein.