Li Jing, Li Ziyi, Gong Hui, Ma Mengyi, Li Shuolei, Yang Huilin, Zhang Hailin, Liu Jianguo
Centre for Bioengineering and Biotechnology, College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao, 266580, China.
Appl Microbiol Biotechnol. 2023 Mar;107(5-6):1725-1736. doi: 10.1007/s00253-023-12430-6. Epub 2023 Feb 16.
In this study, a novel high-activity amylosucrase from Salinispirillum sp. LH10-3-1 (SaAS) was identified and characterized. The recombinant enzyme was determined as a monomer with a molecular mass of 75 kDa. SaAS protein exhibited the maximum total and polymerization activities at pH 9.0 and maximum hydrolysis activity at pH 8.0. The optimum temperature for total, polymerization, and hydrolysis activities were 40, 40, and 45 °C, respectively. Under the optimal pH and temperature, SaAS had a specific activity of 108.2 U/mg. SaAS also showed excellent salt tolerance and could retain 77.4% of its original total activity at 4.0 M NaCl. The addition of Mg, Ba, and Ca enhanced the total activity of SaAS. When the conversion of 0.1 M and 1.0 M sucrose was catalyzed at pH 9.0 and 40 °C for 24 h, the ratios of hydrolysis, polymerization, and isomerization reactions were 11.9:77.4:10.7 and 15.3:53.5:31.2, respectively. The α-arbutin yield of 60.3% was achieved from 20 mM sucrose and 5 mM hydroquinone catalyzed by SaAS. KEY POINTS: • A novel amylosucrase from Salinispirillum sp. LH10-3-1 (SaAS) was characterized. • SaAS has the highest specific enzyme activity among all known amylosucrase. • SaAS has hydrolysis, polymerization, isomerization, and glucosyltransferase activities.
在本研究中，鉴定并表征了一种来自盐螺菌属LH10-3-1菌株（SaAS）的新型高活性淀粉蔗糖酶。重组酶被确定为分子量为75 kDa的单体。SaAS蛋白在pH 9.0时表现出最大的总活性和聚合活性，在pH 8.0时表现出最大的水解活性。总活性、聚合活性和水解活性的最适温度分别为40、40和45℃。在最佳pH和温度条件下，SaAS的比活性为108.2 U/mg。SaAS还表现出优异的耐盐性，在4.0 M NaCl条件下可保留其原始总活性的77.4%。添加Mg、Ba和Ca可增强SaAS的总活性。当在pH 9.0和40℃下催化0.1 M和1.0 M蔗糖转化24 h时，水解、聚合和异构化反应的比例分别为11.9:77.4:10.7和15.3:53.5:31.2。由SaAS催化20 mM蔗糖和5 mM对苯二酚可实现60.3%的α-熊果苷产率。要点：• 对来自盐螺菌属LH10-3-1菌株的新型淀粉蔗糖酶（SaAS）进行了表征。• SaAS在所有已知淀粉蔗糖酶中具有最高的比酶活性。• SaAS具有水解、聚合、异构化和糖基转移酶活性。
