Denson A M, Doyle R J
Department of Microbiology and Immunology, University of Louisville, KY 40292, USA.
Arch Oral Biol. 1998 Jan;43(1):33-8. doi: 10.1016/s0003-9969(97)00089-7.
Cell suspensions of Streptococcus sobrinus can be aggregated by high molecular-weight alpha-1,6 glucans. The aggregation depends on the fidelity of a cell wall-bound, glucan-binding lectin (GBL). It is thought that the lectin may play a part in the sucrose-dependent accretion of streptococci in dental plaques. Results showed that the anionic detergent, sodium dodecyl sulphate (SDS) was a potent inhibitor of the lectin. When cells were incubated in SDS and washed to remove the detergent, lectin activity was diminished. Following incubation of the cells with SDS in the presence of glucan T-10, a low molecular-weight alpha-1,6 glucan, the loss of activity was less pronounced, suggesting that the glucan afforded partial protection against denaturation. Urea and guanidine hydrochloride were good inhibitors of the lectin, but, unlike SDS, were not able to inhibit it irreversibly, except at very high concentrations. Cationic detergents, such as cetylpyridinium bromide (and chloride), also irreversibly denatured the streptococcal lectin, but were not as effective as SDS in abolishing its activity. The results suggest that alpha-1,6 glucan stabilizes the GBL of S. sobrinus, rendering it more resistant to the effect of chaotropes. This may be one reason why dental plaques tend to resist detergents in dentrifices.
远缘链球菌的细胞悬液可被高分子量的α-1,6葡聚糖聚集。这种聚集取决于细胞壁结合的葡聚糖结合凝集素（GBL）的活性。据认为，该凝集素可能在牙菌斑中链球菌的蔗糖依赖性黏附中起作用。结果表明，阴离子洗涤剂十二烷基硫酸钠（SDS）是该凝集素的有效抑制剂。当细胞在SDS中孵育并洗涤以去除洗涤剂后，凝集素活性降低。在葡聚糖T-10（一种低分子量的α-1,6葡聚糖）存在下，将细胞与SDS一起孵育后，活性丧失不太明显，这表明葡聚糖提供了部分抗变性保护。尿素和盐酸胍是该凝集素的良好抑制剂，但与SDS不同，除非在非常高的浓度下，它们不能不可逆地抑制它。阳离子洗涤剂，如十六烷基溴化吡啶（和氯化物），也会使链球菌凝集素不可逆地变性，但在消除其活性方面不如SDS有效。结果表明，α-1,6葡聚糖可稳定远缘链球菌的GBL，使其对离液剂的作用更具抗性。这可能是牙菌斑往往能抵抗牙膏中洗涤剂的原因之一。
