Ortiz-Soto Maria Elena, Ertl Julia, Mut Jürgen, Adelmann Juliane, Le Thien Anh, Shan Junwen, Teßmar Jörg, Schlosser Andreas, Engels Bernd, Seibel Jürgen
Institut für Organische Chemie , Universität Würzburg , Am Hubland , 97074 Würzburg , Germany . Email:
Institut für Physikalische und Theoretische Chemie , Universität Würzburg , Emil-Fischer Strasse 42 , 97074 Würzburg , Germany.
Chem Sci. 2018 May 22;9(24):5312-5321. doi: 10.1039/c8sc01244j. eCollection 2018 Jun 28.
Carbohydrate processing enzymes are sophisticated tools of living systems that have evolved to execute specific reactions on sugars. Here we present for the first time the site-selective chemical modification of exposed tyrosine residues in SacB, a levansucrase from (-LS) for enzyme engineering purposes an ene-type reaction. -LS is unable to sustain the synthesis of high molecular weight (HMW) levan (a fructose polymer) due to protein-oligosaccharide dissociation events occurring at an early stage during polymer elongation. We switched the catalyst from levan-like oligosaccharide synthesis to the efficient production of a HMW fructan polymer through the covalent addition of a flexible chemical side-chain that fluctuates over the central binding cavity of the enzyme preventing premature oligosaccharide disengagement.
碳水化合物加工酶是生命系统中复杂的工具，它们经过进化以对糖类执行特定反应。在此，我们首次展示了为酶工程目的对来自枯草芽孢杆菌（-LS）的果聚糖蔗糖酶SacB中暴露的酪氨酸残基进行位点选择性化学修饰——一种烯反应。由于在聚合物延伸早期发生蛋白质-寡糖解离事件，-LS无法维持高分子量（HMW）果聚糖（一种果糖聚合物）的合成。我们通过共价添加一个在酶的中央结合腔内波动的柔性化学侧链，将催化剂从类似果聚糖的寡糖合成转变为高效生产HMW果聚糖聚合物，从而防止寡糖过早脱离。
