Bunick F J, Kashket S
Infect Immun. 1981 Dec;34(3):856-63. doi: 10.1128/iai.34.3.856-863.1981.
The enolase from a highly fluoride-sensitive strain of Streptococcus salivarius and its fluoride-resistant mutant, as well as those from strains of Streptococcus sanguis and Streptococcus mutans with intermediate and low sensitivities to fluoride have been shown to be inhibited by fluoride. Comparisons of the purified, strain-specific enzymes showed a high degree of similarity for all preparations. The Michaelis constants for the substrate 2-phosphoglycerate were 1.3 x 10(-4) to 2.4 x 10(-4) M, pH optima were 7.3 to 7.7, and Mg2+ optima were 2 mEq/liter for all. Inhibition by fluoride required the presence of inorganic phosphate and was competitive in nature, and the calculated modified inhibition indices were found to be in the range from 3.3 x 10(-14) to 5.8 x 10(-14) M4. Percent inhibitions were determined under standardized conditions (0.16 mM NaF, 2 mM MgSO4, 0.5 mM Pi, and 0.5 mM 2-phosphoglycerate) and were found to range from 53.3 to 65.9% for all of the purified enzymes. The differences do not appear to be meaningful metabolically. Inhibition was reduced to about 14% at pH 6.0. From the similarities in the behavior of the strain-specific enzymes it is concluded that the differences in the glycolytic sensitivities of the different strains of streptococci to fluoride are not the consequence of any kinetic differences between the respective enolases.
来自高氟敏感唾液链球菌菌株及其耐氟突变体的烯醇酶，以及来自对氟敏感性中等和低的血链球菌和变形链球菌菌株的烯醇酶已被证明会受到氟的抑制。对纯化的菌株特异性酶的比较表明，所有制剂都具有高度相似性。所有制剂对底物2-磷酸甘油酸的米氏常数为1.3×10⁻⁴至2.4×10⁻⁴M，最适pH为7.3至7.7，最适Mg²⁺为2 mEq/升。氟的抑制作用需要无机磷酸盐的存在，并且本质上是竞争性的，计算得出的修饰抑制指数在3.3×10⁻¹⁴至5.8×10⁻¹⁴M⁴范围内。在标准化条件（0.16 mM NaF、2 mM MgSO₄、0.5 mM Pi和0.5 mM 2-磷酸甘油酸）下测定抑制百分比，发现所有纯化酶的抑制百分比范围为53.3%至65.9%。这些差异在代谢上似乎没有意义。在pH 6.0时，抑制作用降低至约14%。从菌株特异性酶行为的相似性可以得出结论，不同链球菌菌株对氟的糖酵解敏感性差异不是各自烯醇酶之间任何动力学差异的结果。
