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首页> 外文期刊>Infection and immunity >Characterization of a dextranase produced by an oral strain of Actinomyces israelii.
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Characterization of a dextranase produced by an oral strain of Actinomyces israelii.

机译：以色列放线菌的口服菌株产生的葡聚糖酶的表征。

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摘要

A dextranase-producing, gram-positive, anaerobic, rod-shaped bacterium isolated from human dental plaque was identified as Actinomyces israeli. Although the extracellular dextranase (EC 3.2.1.11) formed by this microbe appeared to be constitutively produced, the bacterium did not utilize the reaction products as a carbon source during growth. A striking feature of the dextranase was the formation of two distinct groups of oligosaccharide end products. The two groups presumably correspond to the limit dextran and the released reaction product which appeared to be cleaved from the end(s) of larger dextran molecules. Low levels of dextranase activity were measured by [3H]NaBH4 reduction and alcohol fixation of the large, tritiated end products on filter paper disks. Of the carbohydrate substrates tested, only alpha-1,6-linked glucans were cleaved. The enzyme did not exhibit any metal ion requirements, and its pH optimum was 6.3. It is suggested that the A. israelii dextranase may function as a regulatory factor during extracellular in vivo glucan synthesis from sucrose by various plaque microbes.
机译：从人类牙菌斑中分离出的产生葡聚糖酶的革兰氏阳性厌氧棒状细菌被鉴定为以色列放线菌。尽管该微生物形成的细胞外葡聚糖酶（EC 3.2.1.11）似乎是组成性产生的，但细菌在生长过程中并未利用反应产物作为碳源。葡聚糖酶的一个显着特征是形成了两组不同的寡糖终产物。这两个基团大概对应于极限葡聚糖和似乎从较大的葡聚糖分子的末端裂解的释放的反应产物。通过将[3H] NaBH4还原并在滤纸圆盘上将大量的ti化终产物进行醇固定，可以测量出较低的葡聚糖酶活性。在所测试的碳水化合物底物中，仅α-1,6-连接的葡聚糖被裂解。该酶没有任何金属离子的要求，其最适pH为6.3。提示以色列曲霉葡聚糖酶可以在各种菌斑微生物从蔗糖合成细胞外体内葡聚糖的过程中起调节因子的作用。

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