Effect of Site-directed Mutagenesis of K178M, S170F and G180V on the Thermostability of Xylanase XynZF-2
This research was aimed to analyze xylanase (XynZF-2) from Aspergillus niger by bioinformatics. The mutant xylanase gene (xynMFV) was acquired by site-directed mutagenesis of amino acid in α-helix 178 site, 170 site and 180 site (K178M, S170F, G180V). Subsequently, the recombinant expression vector was constructed and transformed into E. coli BL21 (DE3) to have a inducible expression. The analysis of enzymatic properties showed that the optimum temperature of the mutant xylanase XynMFV was 50℃, which was 10℃ higher than that of the original xylanase XynZF 2 (40℃). Incubated at 40℃ for 1 h, the relative activity of the mutant xylanase XynMFV was decreased to 56.0％ before heat treatment, while the original xylanase XynZF-2 was decreased to 42.0％. At 45℃, the halftime of inactivation (t1/2) for the mutant xylanase XynMFV was 21 min, which was improved by 14 min compared with the original xylanase XynZF-2 (t1/2=7 min). The results suggested that the site-directed mutagenesis of K178M, S170F and G180V could improve the optimum temperature and thermostability of xylanase XynZF-2.
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万方数据
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