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首页> 外文期刊>Infection and immunity >Levan and levansucrase of Actinomyces viscosus.
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Levan and levansucrase of Actinomyces viscosus.

机译：放线菌的Levan和levansucrase粘性。

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A levansucrase was demonstrated in the growth medium and in association with the cell surface of Actinomyces viscosus. The amount of enzyme produced relative to cell density is not significantly affected by the growth conditions. Sugar alcohols inhibit growth of the cells. The levansucrase hydrolyzes sucrose to produce free glucose and levan; some free fructose is also formed. There is no requirement for cofactors. The Km for sucrose is 12 mM. A variety of heavy metal ions and two disaccharides, lactose and cellobiose, inhibit the enzyme. The levansucrase was purified to homogeneity and has a specific activity of 90 micronmol of glucose release per min per mg. The enzyme has a molecular weight of 220,000 and is composed of subunits of molecular weight 80,000. The levan product contains both beta(2 leads to 1) and beta(2 leads to 6) linkages. The enzyme remains tightly bound to the levan product, resulting in the formation of high-molecular-weight polymer on the order of 10(8) daltons. The possible role of the levan and levansucrase of A. viscosus in the pathogenesis of periodontal disease is discussed.
机译：在生长培养基中和粘性放线菌的细胞表面均证实有蔗糖酶。相对于细胞密度产生的酶的量不受生长条件的显着影响。糖醇抑制细胞的生长。左蔗糖酶水解蔗糖产生游离的葡萄糖和左旋糖。一些游离的果糖也会形成。不需要辅因子。蔗糖的Km为12 mM。多种重金属离子和两种二糖（乳糖和纤维二糖）抑制该酶。将精蔗糖酶纯化至均质，并具有每分钟每毫克释放90微纳摩尔葡萄糖的比活性。该酶的分子量为220,000，由分子量为80,000的亚基组成。 levan产品包含beta（2导致1）和beta（2导致6）链接。该酶仍然与levan产物紧密结合，导致形成10（8）道尔顿量级的高分子量聚合物。讨论了粘性链霉菌的左聚糖和左蔗糖酶在牙周疾病发病机理中的可能作用。

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