Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8327480 | International Journal of Biological Macromolecules | 2018 | 39 Pages |
Abstract
To improve the thermostability of α-L-rhamnosidase (r-Rha1), an enzyme previously identified from Aspergillus niger JMU-TS528, multiple arginine (Arg) residues were introduced into the r-Rha1 sequence to replace several lysine (Lys) residues that located on the surface of the folded r-Rha1. Hinted by in silico analysis, five surface Lys residues (K134, K228, K406, K440, K573) were targeted to produce a list of 5 single-residue mutants and 4 multiple-residue mutants using site-directed mutagenesis. Among these mutants, a double Lys to Arg mutant, i.e. K406R/K573R, showed the best thermostability improvement. The half-life of this mutant's enzyme activity increased 3â¯h at 60â¯Â°C, 23â¯min at 65â¯Â°C, and 3.5â¯min at 70â¯Â°C, when compared with the wild type. The simulated protein structure based interaction analysis and molecular dynamics calculation indicate that the thermostability improvement of the mutant K406R-K573R was possibly due to the extra hydrogen bonds, the additional cation-Ï interactions, and the relatively compact conformation. With the enhanced thermostability, the α-L-rhamnosidase mutant, K406R-K573R, has potentially broadened the r-Rha1 applications in food processing industry.
Related Topics
Life Sciences
Biochemistry, Genetics and Molecular Biology
Biochemistry
Authors
Lijun Li, Hui Liao, Yan Yang, Jianye Gong, Jianan Liu, Zedong Jiang, Yanbing Zhu, Anfeng Xiao, Hui Ni,