乳糖
化学
基质(水族馆)
β-半乳糖苷酶
产量(工程)
脱脂牛奶
酶
半乳糖苷酶
生物化学
立体化学
催化作用
食品科学
生物
材料科学
生态学
基因表达
冶金
基因
作者
Zongmin Qin,Shuifeng Li,Xin Huang,Wei Kong,Xiangpeng Yang,Sufang Zhang,Lichuang Cao,Yuhuan Liu
标识
DOI:10.1021/acs.jafc.9b04774
摘要
There are ongoing interests in improving the galactooligosaccharide (GOS) synthesis efficiency of β-galactosidase by protein engineering. In this study, an intelligent double-hydrophobic amino acid scanning strategy was proposed and employed to target nine residues forming the glycon-binding site (-1 subsite) of β-galactosidase Bgal1-3. Two mutants C510V and H512I with significantly improved GOS synthesis efficiency were obtained. When 40% (w/v) lactose was used as a substrate, Bgal1-3 reached a maximum GOS yield of 45.3% at 16 h, while the mutants reached higher yields in a much shorter time (59.1% at 10 h for C510V, 51.5% at 2 h for H512I). When skim milk was treated with these enzymes, more GOS was produced (19.9 g/L for C510V, 12.7 g/L for H512I) than that for Bgal1-3 (10.3 g/L) at a lactose conversion of 90%. These results validated hydrophobicity scanning as an efficient method to engineer β-galactosidases into promising catalysts for the preparation of GOS and GOS-enriched milk.
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