| Summary: | 碩士 === 國立中興大學 === 基因體暨生物資訊學研究所 === 99 === Trehalose is a non-reducing disaccharide composed of two glucose molecules bound by an alpha, alpha-1, 1-linkage. Trehalose serves a variety of functions in organisms and protects organisms to survive harsh environments. The ability of trehalose to stabilize macromolecules, therefore, in food, medicine, biochemistry and other fields with a wide range of applications. Trehalose synthase catalytic pathway need only one step to the transformation of maltose into trehalose, and due to the substrate specifcity high and low prices, application high value of trehalose synthase. The thermostable trehalose synthase (PTTS) from thermophilic and acidophilic archaea Picrophilus torridus was cloned previously. Its optimum temperature and pH value are 45 ℃ and pH6.0 respectively. PTTS still perform has a high enzyme activity and stability in 60℃ and pH5.0. To improve the thermostability of PTTS, we designed a series of PTTS mutants and performed thermostability test. The results showed that PTTS mutants S73R, E136A, K137A, K150A, S282R, T251R, S439R, S505R retain enzyme activity, and T251R and S439R are the most thermostable PTTS mutants.
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