一种新型α-甘露糖苷酶的异源表达及酶学性质表征

Heterologous expression and characterization of a novel α-mannosidase

从一株性能优良的黄原胶降解菌Microbacteriumsp.XT11中克隆出α-甘露糖苷酶的编码基因MiMan。该基因大小为3 042bp,编码理论分子质量为112.4ku的蛋白质,该酶204~1 006aa为糖苷水解酶GH38家族催化域。融合His亲和纯化标签的MiMan能够在大肠杆菌中高水平可溶性表达,纯化回收率达8.96%。酶学性质分析结果表明,该酶最适反应温度为40℃,最适反应pH为7.0。该酶在碱性环境具有很强的耐受力,能够耐受的最高pH达12.0。

A novelα-mannosidase-encoding gene MiMan was cloned from an excellent xanthan-degrading strain Microbacterium sp.XT11.MiMan gene was 3 042 bp and the molecular weight of its encoded protein was 112.4 ku.α-mannosidase Mi Man contained a 204-1 006 aa catalytic domain that belonged to glycoside hydrolase GH38 family.Theα-mannosidase Mi Man fused with a His affinity label could be solubly expressed in Escherichi a coli in a high level,and its purification recovery rate could reach to 8.96%.The characterization results showed thatα-mannosidase Mi Man was optimally active at pH 7.0 and 40℃,and alkali-tolerant at a high pH of 12.0.