1 research outputs found
Simultaneously Enhanced Thermostability and Catalytic Activity of Xylanase from Streptomyces rameus L2001 by Rigidifying Flexible Regions in Loop Regions of the N‑Terminus
The
GH11 xylanase XynA from Streptomyces rameus L2001 has favorable hydrolytic properties. However, its poor thermal
stability hinders its widespread application in industry. In this
study, mutants Mut1 and Mut2 were constructed by rationally combining
the mutations 11YHDGYF16, 23AP24/23SP24, and 32GP33. The residual enzyme activity of these combinational mutants was
more than 85% when incubated at 80 and 90 °C for 12 h, and thus
are the most thermotolerant xylanases known to date. The reduced flexibility
of the N-terminus, increased overall rigidity, as well as the surface
net charge of Mut1 and Mut2 may be partially responsible for the improved
thermal stability. In addition, the specific activity and catalytic
efficiency of Mut1 and Mut2 were improved compared with those of wild-type
XynA. The broader catalytic cleft and enhanced flexibility of the
“thumb” of Mut1 and Mut2 may be partially responsible
for the improved specific activity and catalytic efficiency