The N-terminal cellulose-binding domain of EGXA increases thermal stability of xylanase and changes its specific activities on different substrates

• 来源期刊: 生物化学与生物物理学报（英文版）
• 关键词: endo-β-1,4-glucanase endo-β-1,4-xylanase pNPCase CMCase EGXA Ampullaria crossean cellulose-binding domain
• 年，卷（期）: 2008,（11）
• 页码范围: 949-954
• 页数: 6页
• 语种: 英文
• DOI: 10.1111/j.1745-7270.2008.00481.x

摘要

A full-length EGXA enzyme from a mollusk, Ampullaria crossean, was cloned into pFastBac vector and then heterogeneously expressed in insect Tn5 cells. Its natural N-terminal signal peptide worked well in the insect Tn5 cells.The recombinant EGXA was a 63 kDa protein and had active endo-β-1,4-glucanase (EC 3.2.1.4) and endo-β-1,4-xylanase (EC 3.2.1.8). The specific activity of endo-β-1,4-xylanase was higher than in the EGX, which was purified from the stomach tissues of Ampullaria crossen. The N-terminal cellulosebinding domain of EGXA made it bind to cellulose and xylan more efficiently. This cellulose-binding domain also increased the thermal stability of this recombinant enzyme and decreased the recombinant EGXA's specific activities on p-nitrophenyi-β-D-cellobioside and sodium carboxymethyl cellulose.