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Enhancement in catalytic activity of CotA-laccase from Bacillus pumilus W3 via site-directed mutagenesis

2019; Elsevier BV; Volume: 129; Issue: 4 Linguagem: Inglês

10.1016/j.jbiosc.2019.09.020

1389-1723

Kai-Zhong Xu, Haoran Wang, Yajing Wang, Jing Xia, Hui Ma, Yujie Cai, Xiangru Liao, Zheng-Bing Guan,

Microbial Metabolism and Applications

CotA-laccases are potential enzymes that are widely used in decolorization of dyes and degradation of toxic substances. In this study, a novel CotA-laccase gene from Bacillus pumilus W3 was applied for rational design. After a series of site-directed genetic mutations, the mutant S208G/F227A showed a 5.1-fold higher catalytic efficiency (kcat/Km) than the wild-type CotA-laccase did. The optimal pH of S208G/F227A was 3.5 with ABTS as substrate. The residual activity of mutant S208G/F227A was more than 80% after incubated for 10 h at pH 7–11. Mutant S208G/F227A showed optimal temperature at 80°C with ABTS as substrate. The thermal stability of mutant laccase S208G/F227A was lower than that of wild-type CotA-laccase. This study showed that Gly208 and Ala227 play key roles in catalytic efficiency and it is possible to improve catalytic efficiency of CotA-laccase through site-directed mutagenesis.