Sutton S V, Bender G R, Marquis R E
Department of Microbiology and Immunology, University of Rochester, New York 14642.
Infect Immun. 1987 Nov;55(11):2597-603. doi: 10.1128/iai.55.11.2597-2603.1987.
The ATPases of isolated membranes of lactic acid bacteria were found to be inhibited by fluoride in a complex manner. Among the enzymes tested, that of Streptococcus mutans GS-5 was the most sensitive to fluoride, and the initial rate of hydrolysis of ATP was reduced 50% by approximately 3 mM fluoride. The enzyme of Lactobacillus casei ATCC 4646 was the most resistant, and about 25 mM fluoride was required for 50% inhibition. The response to fluoride appeared to involve reversible, noncompetitive inhibition during short exposure to low levels of fluoride and nonreversible inhibition at higher fluoride levels. In addition, kinetic studies of the effects of fluoride on the enzymes of membranes of S. mutans and L. casei indicated that reversible inhibition was at least partly overcome at high levels of either ATP or Mg. The effects of pH on fluoride inhibition of ATPases were markedly different from the effects of pH on inhibition of acid/base regulation of intact cells by fluoride. It appeared that formation of HF was not required for inhibition of the ATPases. F1 ATPases isolated from the membranes by washing with buffers of low ionic strength proved to be less sensitive to fluoride than the membrane-associated F1F0 holoenzymes, and it was concluded that the F0 or membrane sector of the holoenzyme is involved in fluoride inhibition.
研究发现，乳酸菌分离膜中的ATP酶会受到氟化物的复杂抑制。在所测试的酶中，变形链球菌GS-5的酶对氟化物最为敏感，约3 mM氟化物可使ATP的初始水解速率降低50%。干酪乳杆菌ATCC 4646的酶最具抗性，50%抑制率所需的氟化物浓度约为25 mM。对氟化物的反应似乎涉及在短时间暴露于低水平氟化物时的可逆、非竞争性抑制，以及在较高氟化物水平时的不可逆抑制。此外，氟化物对变形链球菌和干酪乳杆菌膜酶影响的动力学研究表明，在高浓度的ATP或Mg存在时，可逆抑制至少部分被克服。pH对ATP酶氟化物抑制的影响与pH对完整细胞氟化物抑制酸/碱调节的影响明显不同。似乎抑制ATP酶并不需要形成HF。用低离子强度缓冲液洗涤从膜中分离出的F1 ATP酶对氟化物的敏感性低于与膜相关的F1F0全酶，由此得出结论，全酶的F0或膜部分参与了氟化物抑制作用。
