Abstract
In order to improve the laccase activity, mutant libraries are constructed through ethyl methane sulfonate-based (EMS) random mutagenesis. Mutagenesis improved expression 3.7-fold to 144 mg l −1 laccase in yeast, together with a 1.4-fold increase in K cat. Thus, the total activity is enhanced 5-fold for 2,2′-azino-bis 3-ethylbenzothiaoline-6-sulfonic acid (ABTS). In the presence of 0.6 mM copper, the highest activity value reached 30 U ml −1 after a 3-day cultivation at a temperature of 30 °C . In comparison with the wild type, the best mutant enzymatic properties ( K m for ABTS and guaiacol, thermo- and pH stability, optimal pH) are not changed. Moreover, amino acid sequence analysis indicates that there are four substitutions in the best mutant laccase (Gly160Asp, Ala167Thr, Gly174Asp, and Glu234Gly). The best mutant laccase model showed that the Gly160 and Ala167 are to be found near the water channel; especially the distance of Ala167 to the Cu3a is 14.46 Å. This implies that it is likely involved in the formation of water channel and that it helps facilitate the easy incoming and outgoing of water.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.