Levan and inulin are two types of fructan. Levan is composed of β-(2, 6) fructosyl linkage and inulin is composed of β-(2, 1) linkage. Both levan and inulin have been accepted and applied in the food, medicinal and chemical industries for their outstanding physicochemical properties in recent years. Microbial levansucrase and inulosucrase are key enzymes responsible for the synthesis of fructan from sucrose. In this review, levansucrase and inulosucrase are discussed together for the first time regarding the evolutionary relationships, bacteria origin, crystal structure, product-forming mechanism and commercial applications. Particularly, some insights into the product specificity about levansucrase and inulosucrase as well as the mechanism for product elongation for fructan are also discussed in the article.

中文翻译：

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Levansucrase和Inulosucrase的最新进展：进化，特征和应用。

莱万和菊粉是果聚糖的两种类型。Levan由β-（2，6）果糖基键组成，而菊粉则由β-（2，1）键组成。近年来，levan和菊粉因其出色的理化特性而被食品，药物和化学工业所接受和应用。微生物左蔗糖酶和芥子糖苷酶是负责由蔗糖合成果聚糖的关键酶。在这篇综述中，关于蔗糖蔗糖酶和芥子糖苷酶的进化关系，细菌起源，晶体结构，产物形成机理和商业应用都首次进行了讨论。特别是，本文还讨论了有关葡糖蔗糖酶和芥酸蔗糖酶产品特异性的一些见解，以及果聚糖的产品延伸机理。