右旋糖苷修饰酵母蔗糖酶条件的筛选及修饰酶性质的研究  

Yeast Invertase Chemically Modified by Dextran and Its Enzyme Properties

作　　者：伍志权[1,2] 黎春怡[3] 麦小珊 郭诗静[2] 黄卓烈[2] 

机构地区：[1]佛山市中南农业科技有限公司检测中心,广东佛山528000 [2]华南农业大学生命科学学院,广东广州510642 [3]茂名职业技术学院,广东茂名525000

出　　处：《华南农业大学学报》2009年第4期48-52,共5页Journal of South China Agricultural University

基　　金：国家自然科学基金(10074016)

摘　　要：以低分子右旋糖苷（Dextran）为修饰剂,选用L16（45）正交试验方案,研究了不同修饰条件对酵母蔗糖酶（Yeast invertase）化学修饰效果的影响以及修饰前后酶的性质变化.结果表明,pH 5.0、20℃、反应8 h为最佳的修饰条件.与天然酶相比,修饰酶的酶比活力、糖含量、酶活力回收率分别提高56.7%、35.05%和14.61%,蛋白含量下降22.66%,氨基修饰率为39.55%.酶学性质研究表明,修饰后酶的最适pH在4.0-5.0范围内,最适温度55-60℃,在pH 3.5缓冲液中稳定性上升,在pH 6.5缓冲液中稳定性下降,在60℃缓冲液中稳定性下降.动力学研究表明,修饰后酶的Km和vm ax均上升,光谱分析表明,修饰后酶的构型构象均发生变化.Dextran was used as the modifying reagent for the chemical modification of yeast invertase. In order to find an optimum way for chemical modification, the effects of different modification condition were studied through orthogonal comparison. The orthogonal analysis showed that the optimum condition for chemical modification was to do the experiment in the solution of pH 5.0 at the temperature of 20 ℃ for 8 h. The specific enzyme activity, polyhydrate content of the modified-enzyme and the activity reserval ratio were increased by 56.7% ,35, 05% and 14.61% ,respectively. However, the protein content of modified-enzyme was decreased by 22.66% , and the ratio of amino modification was 39.55%. The study of zymological properties showed that the optimal pH was at the range of 4.0 -5.0, the optimal temperature range was 50 -60 ℃. The stability of modified-enzyme at pH 3.5 was increased, but the stability at pH 6.5 was decreased. The thermo stability at 60 ℃ was also decreased compared with that of yeast invertase. Kinetics analysis showed that Km and Vmax of modified-enzyme was increased. The spectral analysis showed that the configuration and conformation of modified-enzyme were quite different from that of yeast invertase.

关 键 词：酵母蔗糖酶 右旋糖苷 化学修饰 

分 类 号：Q936[生物学—微生物学]