中文摘要：

宇佐美曲霉（Aspergillus usamii）YL-01-78的糖苷水解酶5家族β-甘露聚糖酶（Au Man5A）是一种仅含催化域（CM）的单结构蛋白。为改善其酶学性质,基于理性设计将海栖热胞菌（Thermotoga maritima）MSB8的27家族碳水化合物结合域（CBM27）融合至Au Man5A的C-端,并采用重叠PCR技术构建融合酶基因Auman5A-cbm27。分别将Auman5A-cbm27和Auman5A在毕赤酵母GS115中进行表达,对重组表达产物re Au Man5A-CBM27和re Au Man5A进行纯化和酶学性质测定。结果表明,re Au Man5A-CBM27和re Au Man5A的最适温度均为68℃;两者分别在68和60℃及以下稳定。同时,前者较后者具有更广泛的p H稳定范围。re Au Man5ACBM27对角豆胶的Km值由融合前的1.7 mg/m L降至0.7 mg/m L,表明Au Man5A的底物亲和力得到了提高。

英文摘要：

AuMan5A,which belongs to the glycoside hydrolase family 5 β-mannanase from Aspergillus usamii YL-01-78,only contains a catalytic module （CM）. To improve its enzymatic properties,a fusion β-mannanase （AuMan5A -CBM27） was well designed by fusing a family 27carbohydrate-binding module （CBM27） from Thermotoga maritima MSB8 into the C-terminus of AuMan5A. A fusion gene （A uman5A -cbm27） constructed by the overlapping PCR was expressed in Pichia pastoris GSll5. The enzymatic properties of the purified reAuMan5A-CBM27 and reAuMan5A were investigated. The optimal temperatures of both reAuMan5A-CBM27 and reAuMan5A were determined at 68 ℃. They were respectively thermo-stabled at 68 ℃ or 60℃ and below. A wider pH tolerant range was observed for reAuMan5A-CBM27 ,whose Km value to locust bean dropped from 1.7 mg/mL to 0.7 mg/mL. The increase of substrate affinity of AuMan5A was confirmed.