Relationship between cell-bound dextransucrase and the agglutination of Streptococcus mutans
Relationship between cell-bound dextransucrase and the agglutination of Streptococcus mutans
复制标题
细胞结合葡聚糖蔗糖酶与变形链球菌凝集的关系
作者：
M. M. Mccabe;E. Smith
葡聚糖诱导的变形链球菌细胞凝集与细胞结合葡聚糖蔗糖酶活性无关。甲苯提取物或Hg 2+或Cu 2+的存在下显着降低或完全废除细胞结合的葡聚糖蔗糖酶活性，而不会对葡聚糖诱导的细胞凝集产生不利影响。在100 ℃下加热直至细胞结合的葡聚糖蔗糖酶完全失活处理的细胞，在由葡聚糖诱导的细胞凝集诱导时继续凝集，该细胞凝集是由胰蛋白酶和几种其它酶处理细胞以及由乙二胺四乙酸处理引起的，而细胞结合的葡聚糖蔗糖酶活性没有相应的损失。细胞对低分子量的支链葡聚糖的亲合力大于对相同重量的直链葡聚糖的亲合力，这表明单独的大小并不能决定葡聚糖作为凝集诱导剂的效率。蔗糖和葡聚糖诱导的S.变形K1-R细胞。虽然菌株6715-49的正常细胞似乎不需要二价阳离子的凝集，热和乙二胺四乙酸处理的细胞特别需要Ca 2+。Ca ~（2+）在细胞凝集中的作用可能是激活细胞表面葡聚糖受体或形成特异性的细胞间Ca ~（2+）桥。
Dextran-induced agglutination of Streptococcus mutans cells is independent of cell-bound dextransucrase activity. Toluene extraction or the presence of Hg2+ or Cu2+ markedly decreased or completely abolished cell-bound dextransucrase activity without adversely affecting dextran-induced cell agglutination. Cells treated by heating at 100 C until cell-bound dextransucrase was completely inactivated continued to agglutinate when induced by dextran-induced cell agglutination resulted from cell treatment with trypsin and several other enzymes, as well as from ethylenediaminetetraacetic acid treatment, without a corresponding loss of cell-bound dextransucrase activity. Cells possessed a greater avidity for branched dextrans of low molecular weight than for linear dextrans of the same weight, indicating that size alone does not determine the efficiency of dextran as an inducer of agglutination. Divalent metal ions were required for both sucrose- and dextran-induced agglutination of S. mutans K1-R cells. Although normal cells of strain 6715-49 did not appear to require divalent cations for agglutination, heat- and ethlyenediaminetetraacetic acid-treated cells specifically required Ca2+. The role of Ca2+ in cell agglutination may be either to activate the cell-surface dextran receptor or to form specific intercellular Ca2+ bridges.