钾离子和钠离子对碱性pH条件下呼吸代谢的大肠杆菌质子动力的影响。
Effects of K+ and Na+ on the proton motive force of respiring Escherichia coli at alkaline pH.
作者信息
Kashket E R
出版信息
J Bacteriol. 1985 Aug;163(2):423-9. doi: 10.1128/jb.163.2.423-429.1985.
The role of K+ and Na+ in the maintenance of the proton motive force (delta p) was studied in Escherichia coli incubated in alkaline media. Cells respiring in Tris buffer (pH 7.8) that contained less than 100 microEq of K+ and Na+ per liter had a normal delta p of about -165 mV. At pH 8.2, however, the delta p was reduced significantly. The decrease in delta p at pH 8.2 was due to a marked decrease in the transmembrane potential (delta psi), while the internal pH remained at 7.5 to 7.7. When KCl or NaCl, but not LiCl or choline chloride, was added to the cells, the delta psi rose to the values seen at an external pH of 7.8. In addition, choline chloride inhibited the enhancement of delta psi by K+. None of the salts had a significant effect on the internal pH. The effects can be attributed to alterations of K+ or Na+ cycling in and out of the cells via the known K+ and Na+ transport systems.
在碱性培养基中培养的大肠杆菌中，研究了钾离子（K⁺）和钠离子（Na⁺）在维持质子动力（Δp）中的作用。在每升含钾离子和钠离子少于100微当量的Tris缓冲液（pH 7.8）中进行呼吸作用的细胞，其正常的Δp约为-165 mV。然而，在pH 8.2时，Δp显著降低。pH 8.2时Δp的降低是由于跨膜电位（Δψ）显著下降，而细胞内pH仍保持在7.5至7.7。当向细胞中添加氯化钾（KCl）或氯化钠（NaCl），而不是氯化锂（LiCl）或氯化胆碱时，Δψ上升到在外部pH 7.8时所观察到的值。此外，氯化胆碱抑制了钾离子对Δψ的增强作用。这些盐类均对细胞内pH没有显著影响。这些效应可归因于通过已知钾离子和钠离子转运系统进出细胞的钾离子或钠离子循环的改变。
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