Synthesis of thermostablemutants of the trichoderma reesei xylanase

摘要

The thermostability, temperature and pH optima of Trichoderna reese xylanase II(TrX) have been increased by protein engineering. This was accomplished through the substiution of its (1-29) region with the corresponding seuqnece of the Thermomonsopora fusca xylanase (TfX). The resultant chieric xylanase showed an improvement of + 10 deg C and + 0.7 unit in the optimal temperature and pH as compared to the recombinant wild-type TrX. Upstream extension from the-1 position of the new xylanase with a tripeptide G-R-R, elevated the optimal temperature and pH by 13 deg C and 0.9 unit respectively. An improvement of thermostability by 15 deg C was also observed. Site-specific mutagenesis of the (1-29) region of TrX identified three mutations (Asn 10His, Tyr27Met and Asn29Leu) essenial for the improvement in the chimeric xylanase.