定向进化提高来源于Arthrobacter ramosus的MTHase的热稳定性

麦芽寡糖基海藻糖水解酶(mahosyhrehalose hydrolase,MTHase)是以淀粉或麦芽糊精为底物制备海藻糖的关键酶之一.来源于Arthrobacter ramosus的MTHase,表达量好,比活高,但热稳定性差,限制了其工业化应用.采用定向进化技术,筛选得到L137M和A216T两个突变体,在60℃...

Improved the Thermostability of MTHase from Arthrobacter ramosus by Directed Evolution

Maltosyltrehalose hydrolase(MTHase)is one of the key enzymes for trehalose production using starch or maltodextrin as the substrate.MTHase from Arthrobacter ramosus has a good-level expression and high specific activity,but poor thermostability,which limits its industrial application.In this study,mutants of L137M and A216T were screened using the directed evolution.The half-life(t1/2,at 60℃)of wild-type,L137M and A216T were 15.5,20.5 and 23.3 min,respectively.The half-period t1/2 of L137M and A216T were 1.3-and 1.5-fold than that of the wild type,respectively.The performances of L137M and A216T and wild-type enzymes were further investigated by their trehalose yields from MTSase at 60℃.Under the same amount of enzyme,the trehalose conversion rates by wild-type,L137M and A216T were 51.3%,52.6%and 55.7%,respectively.The trehalose conversion rates by the two mutants were higher than that by the wild-type,indicating that the improved thermostability of the mutants is beneficial for industrial trehalose production.