Sodium and Potassium Requirements for Active Transport of Glutamate by Escherichia coli K-12
Sodium and Potassium Requirements for Active Transport of Glutamate by Escherichia coli K-12
复制标题
大肠杆菌 K-12 主动转运谷氨酸的钠和钾需求
DOI：
10.1128/jb.114.1.53-58.1973
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发表时间：
1973
影响因子：
3.2
通讯作者：
K. Druck
中科院分区：
文献类型：
--
作者：
Y. S. Halpern;H. Barash;S. Dover;K. Druck
大肠杆菌K-12谷氨酸的主动转运需要Na+和K+离子。增加培养基中Na+的浓度导致谷氨酸吸收系统的Km降低;容量不受影响。未处理细胞的谷氨酸摄取不受K+刺激。K+耗尽的细胞显示出谷氨酸吸收能力大大降低。当Na+离子也存在于摄取培养基中时，在K+存在下预孵育这样的细胞完全恢复其谷氨酸摄取能力。单独添加K+或Na+时，谷氨酸吸收仅恢复到两种阳离子存在下最大容量的约20%。K+浓度的变化影响谷氨酸吸收的能力，但对谷氨酸转运系统的Km没有影响。哇巴因不抑制（Na ~+-K ~+）刺激的E. coli K-12。
Active transport of glutamate by Escherichia coli K-12 requires both Na+ and K+ ions. Increasing the concentration of Na+ in the medium results in a decrease in the Km of the uptake system for glutamate; the capacity is not affected. Glutamate uptake by untreated cells is not stimulated by K+. K+-depleted cells show a greatly reduced capacity for glutamate uptake. Preincubation of such cells in the presence of K+ fully restores their capacity for glutamate uptake when Na+ ions are also present in the uptake medium. Addition of either K+ or Na+ alone restores glutamate uptake to only about 20% of its maximum capacity in the presence of both cations. Changes in K+ concentration affect the capacity for glutamate uptake but have no effect on the Km of the glutamate transport system. Ouabain does not inhibit the (Na+-K+)-stimulated glutamate uptake by intact cells or spheroplasts of E. coli K-12.