碱性木聚糖酶在毕赤酵母的表达及酶学性质研究

摘要

In this study,xylanase gene (xynAeSC) from Streptomyces chartreusis L1105 without carbohydrate binding domain (CBD) was cloned into expression vector.Recombinant strain (GS115-3-20) was fermented under the optimal condition for enzyme production.The yield of xylanase enzyme was up to 683 ± 9 U/mL.Results showed that recombinant xylanase had the high relative enzyme activity at pH 6.2 ～ 8.6,especially at 7.2.It had the relative activity more than 70％ at 40 ～ 60 ℃2.The optimal temperature was around 70 ℃.It also showed the highest specific activity towards Oat-speh xylan (equal to 259.7％ ± 10.7％ of relative activity towards Birch xylan).It also showed the lowest activity towards sugar cane pulp xylan (only equal to 16.0％ ± 1.5％ of relative activity towards Birch xylan).Its activity and properties had not significantly affected by removing CBD domain.All these study made this expression system attractive for industrial applications.%将教酒链霉菌L1105第10家族碱性木聚糖酶基因去除纤维素结合域(CBD)后将功能结构域基因xyn-AeSC克隆到毕赤酵母表达载体.经筛选得到重组工程菌GS1153-20,用甲醇诱导后产酶活力达到最高683±9U/mL.结果表明,重组木聚糖酶的最适pH为7.2,且在pH 6.2 ～8.6有较高的相对酶活;其最适温度为70℃,40～ 60℃时相对酶活力都在70％以上;重组酶XynAeSC以燕麦木聚糖为底物时,酶活力最高,相对酶活力为桦木的259.7％±10.7％;对甘蔗渣木聚糖的酶活力最低,只有对桦木木聚糖酶活的16.0％±1.5％.研究表明,碱性木聚糖酶基因成功地在毕赤酵母中表达,且去除CBD域后,其酶学性质并未改变.