蔗糖异构酶PalI在解脂耶氏酵母中的高水平表达及酶学性质表征

High expression and characterization of sucrose isomerase PalI in Yarrowia lipolytica

异麦芽酮糖是一种重要的工业原料和食品原料,来自Klebsiella sp.LX3的蔗糖异构酶能够有效催化蔗糖异构化为异麦芽酮糖。为研究食品安全型蔗糖异构酶,并提高蔗糖异构酶的产量与酶活力,对蔗糖异构酶的编码基因PalI进行密码子优化,构建于解脂耶氏酵母外泌表达菌株,获得重组蔗糖异构酶PalI。酶活力测定结果表明,其酶活力为916 U/mg,高于以往报道的蔗糖异构酶酶活力。酶学性质分析结果表明,该酶最适作用温度为40℃,最适pH为5.7,且该酶对酸性及碱性环境的耐受力范围较广,较以往报道的蔗糖异构酶的稳定性有显著提高。重组酶PalI能够有效地与蔗糖反应,主产物为异麦芽酮糖和海藻酮糖,存在少量副产物。

Isomaltulose is an important industrial and food raw material.Sucrose isomerase from Klebsiella sp.LX3 can effectively catalyze the isomerization of sucrose to isomaltulose.To study the food safety sucrose isomerase and improve the yield and activity of sucrose isomerase,the codon gene PalI of sucrose isomerase was optimized and constructed the recombinant sucrose isomerase PalI in the exocrine expression strain of Yarrowia lipolytica.The enzyme activity was 916 U/mg,which was higher than that of sucrose isomerase reported previously.The results showed that the optimum temperature and pH of the enzyme were 40℃and 5.7,respectively.The enzyme had a wide tolerance to acidic and alkaline environment,and its stability was significantly higher than that of sucrose isomerase reported previously.Recombinant PalI can effectively react with sucrose.The main products are isomaltulose and trehalose,with a small amount of by-products.