文献类型：期刊文献

英文题名：Expression, characterization and structural profile of a heterodimeric β-galactosidase from the novel strain Lactobacillus curieae M2011381

作者：Zhu, Jiaying[1];Sun, Jiaqi[1];Tang, YaJie[2];Xie, Jingli[1,3];Wei, Dongzhi[1,3]

机构：[1]East China Univ Sci & Technol, Sch Biotechnol, Dept Food Sci & Technol, State Key Lab Bioreactor Engn, Shanghai 200237, Peoples R China;[2]Shandong Univ, State Key Lab Microbial Technol, Qingdao 266237, Peoples R China;[3]Shanghai Collaborat Innovat Ctr Biomfg SCICB, Shanghai 200237, Peoples R China

年份：2020

卷号：97

起止页码：87

外文期刊名：PROCESS BIOCHEMISTRY

收录：;EI(收录号：20202808915705);WOS:【SCI-EXPANDED(收录号:WOS:000569089800011)】；

基金：This study was financially supported by the Open Funding Project of the Key Laboratory of Fermentation Engineering (Ministry of Education) of China and the National Natural Science Foundation of China (31772007, 31801489).

语种：英文

外文关键词：beta-Galactosidase; Heterodimer; Lactobacillus curieae M2011381; Structure; Molecular docking

摘要：A heterodimeric beta-galactosidase was discovered in the novel strain Lactobacillus curieae M2011381. The gene encoding the enzyme was expressed in Escherichia coli BL21 (DE3). The specific enzyme activities of the recombinant holoenzyme (LacLM) and large subunit (LacL) measured 11.4 U/mg and 3.8 U/mg, respectively. The kcat/Km values of LacLM and LacL were 740 mM(-1) s(-1) and 1.40 mM(-1) s(-1), respectively. LacLM showed maximum activity at pH 8.0 and 55 degrees C, and it could maintain its activity at a neutral pH and below 45 degrees C. LacLM displayed both hydrolysis and transgalactosylation activity on 200 g/L lactose. When LacLM was added to milk, the lactose was hydrolyzed after 6 h without galactooligosaccharide generation. The sequence alignment and homology modeling of the structures of the holoenzyme and subunits revealed that LacL has a catalytic domain with a catalytic dyad, Glu470 and Glu538, and small subunit LacM is a beta-sheet domain with a conserved Trp294. The molecular docking of LacLM helped to illustrate the roles of both subunits in the reaction with lactose.