Germaine G R, Tellefson L M
Infect Immun. 1981 Dec;34(3):871-9. doi: 10.1128/iai.34.3.871-879.1981.
The fluoride (F) sensitivity of glucose uptake by whole cell suspensions of streptococcus mutans in the presence and absence of human whole salivary supernatant was studied. It was observed that dithiothreitol (DTT) and other thiols markedly reduced the F sensitivity of cells when saliva (50%, vol/vol) was present during glucose uptake. In the absence of saliva, cells were sensitive to 2 to 2.5 mM F regardless of the presence of thiols. Supplementation of cells in phosphate or tris(hydroxymethyl)aminomethane-hydrochloride buffers with physiological concentrations of calcium or phosphate had no effect on the F sensitivity of the organism. Experiments with permeabilized cells suggested that thiols themselves had no direct effect on the F sensitivity of enolase (a principal F target). Cells pretreated with DDT subsequently exhibited decreased F sensitivity when examined in the presence of saliva but not in the absence of saliva. Cells pretreated with whole salivary supernatant were found to be subsequently less sensitive to F in the absence of saliva during glucose uptake. Furthermore, in cases where cells were pretreated with saliva, subsequent additions of DDT were unnecessary to obtain maximal reduction in the F sensitivity of glucose uptake. It was concluded that the saliva-dependent reduction in F sensitivity of glucose uptake was not due to sequestration of available F by salivary constituents. The data suggest that a salivary component(s) interacts directly with the microorganism in some manner which results in reduced F sensitivity of the process under study. Possible mechanisms of saliva action are discussed.
研究了在存在和不存在人全唾液上清液的情况下，变形链球菌全细胞悬液对葡萄糖摄取的氟（F）敏感性。观察到，当在葡萄糖摄取期间存在唾液（50%，体积/体积）时，二硫苏糖醇（DTT）和其他硫醇显著降低了细胞对F的敏感性。在不存在唾液的情况下，无论是否存在硫醇，细胞对2至2.5 mM F敏感。用生理浓度的钙或磷酸盐补充磷酸盐或三（羟甲基）氨基甲烷 - 盐酸盐缓冲液中的细胞，对该生物体的F敏感性没有影响。对透化细胞的实验表明，硫醇本身对烯醇化酶（主要的F靶点）的F敏感性没有直接影响。用DDT预处理的细胞随后在存在唾液的情况下检测时表现出F敏感性降低，但在不存在唾液的情况下则不然。发现用全唾液上清液预处理的细胞在葡萄糖摄取期间不存在唾液的情况下随后对F的敏感性较低。此外，在细胞用唾液预处理的情况下，随后添加DDT对于最大程度降低葡萄糖摄取的F敏感性是不必要的。得出的结论是，唾液依赖性降低葡萄糖摄取的F敏感性不是由于唾液成分螯合了可用的F。数据表明，唾液成分以某种方式直接与微生物相互作用，导致所研究过程的F敏感性降低。讨论了唾液作用的可能机制。
