Li Youran, Xu Jingjing, Zhang Liang, Ding Zhongyang, Gu Zhenghua, Shi Guiyang
Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu Province 214122, China.
Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu Province 214122, China.
Carbohydr Res. 2017 Jun 29;446-447:93-100. doi: 10.1016/j.carres.2017.05.016. Epub 2017 May 22.
Debranching enzymes contribute to the enzymatic production of resistant starch (RS) by reducing substrate molecular weight and increasing amylose yield. In the present study, the action pattern of a thermostable isoamylase-type debranching enzyme on different types of starch was investigated. The molecular weight distribution, glycosidic bond composition and contents of oligosaccharides released were monitored by various liquid chromatography techniques and nuclear magnetic resonance spectroscopy (NMR). These analyses showed that the isoamylase could specifically and efficiently attack α-1,6-glucosidic linkages at branch points, leaving the amylose favored by other amylolytic enzymes. Its ability to attack side chains composed of 1-3 glucose residues differentiates it from other isoamylases, a property which is also ideal for the RS preparation process. The enzyme was used as an auxiliary enzyme in the hydrolytic stage. The highest RS yield (53.8%) was achieved under the optimized conditions of 70 °C and pH 5.0, using 7 U isoamylase per g starch and 2 NU amylase per g starch. These data also help us better understand the application of isoamylase for preparation of other products from highly branched starch materials.
脱支酶通过降低底物分子量和提高直链淀粉产量，有助于酶法生产抗性淀粉（RS）。在本研究中，研究了一种耐热异淀粉酶型脱支酶对不同类型淀粉的作用模式。通过各种液相色谱技术和核磁共振光谱（NMR）监测了释放的低聚糖的分子量分布、糖苷键组成和含量。这些分析表明，异淀粉酶可以特异性且高效地攻击分支点处的α-1,6-糖苷键，使直链淀粉受到其他淀粉分解酶的青睐。它攻击由1-3个葡萄糖残基组成的侧链的能力使其与其他异淀粉酶不同，这一特性对于RS制备过程也是理想的。该酶在水解阶段用作辅助酶。在70°C和pH 5.0的优化条件下，每克淀粉使用7 U异淀粉酶和每克淀粉2 NU淀粉酶，可实现最高的RS产量（53.8%）。这些数据也有助于我们更好地理解异淀粉酶在从高度分支淀粉材料制备其他产品中的应用。
