酶促水解斯替夫苷制甜茶苷及其反应路径解析

Enzymatic Preparation of Rubusoside from Stevioside and Its Reaction Route

摘要:

β-葡萄糖苷酶可催化水解斯替夫苷生成甜茶苷,但是斯替夫苷分子中具有3个以β-1,2键连接的葡萄糖残基；反应过程中可能产生甜茶苷、甜菊双糖苷、甜菊醇单葡萄糖酯、甜菊单糖苷和甜菊醇。该水解反应的副产物的结构解析较少，反应路径解析更少，合成通量也较低，不利于工业化。以来自Aspergillus niger的β-葡萄糖苷酶催化水解斯替夫苷高通量生成甜茶苷，并通过底物特异性分析实验、产物和副产物结构解析以及过程中各组分经时变化的分析，解析β-葡萄糖苷酶催化水解斯替夫苷的具体过程。实验结果表明，该酶对斯替夫苷具有特异性，水解主产物为甜茶苷，首次阐明副产物甜菊醇单葡萄糖酯由斯替夫苷直接水解槐糖基生成，而非甜茶苷的进一步水解产物。

Abstract:

β-glucosidase may stimulate hydrolysis of stevioside to produce rubusoside. However,there are three β-1,2-glucose residues in stevioside molecule, which may produce rubusoside, steviolbioside, steviol glucosyl ester, steviolmonoside and steviol during the hydrolysis. To date, the structures of by-products remain unclear, and the analysis of reaction route is even more limited. The reported production throughput is not high enough for industry production. β-glucosidase from Aspergillus niger was applied to catalyze the hydrolysis of stevioside for rubusoside production in high-throughput. This reaction route was analyzed through substrate specificity test, structural characterization of products and by-products, and analysis of real-time composition. The results indicate that the enzyme is specific to stevioside. The main hydrolysis product is rubusoside, and it is demonstrated for the first time that the by-product, steviol glucosyl ester, is directly produced by hydrolyzing sophorosyl group of stevioside instead of the hydrolysate of rubusoside.