Anraku Y, Goto F, Kin E
J Biochem. 1975 Jul;78(1):149-57.
A mutant (S-1) of Escherichia coli which lacks succinate dehydrogenase [EC 1.3.99.1] but has normally succinate transport system, and various oxidase activities other than succinate, was isolated from the strain U24. Using these strains studies were made on the effects of zinc ions on the active transport reactions for succinate proline, and leucine. Zinc ions inhibited succinate transport reaction and succinate oxidation by intact cells. The active transport reaction for proline, which was supported by endogenous energy source in intact cells, was slightly inhibited by zinc ions. This inhibition was not reversed by large excess of magnesium ions. The initial rates of active uptakes of proline were increased by exogenous energy sources such as succinate and glycerol and zinc ions greatly inhibited these. However, D-lactate dependent proline uptake was enhanced slightly by the presence of zinc ions. It was found that zinc ions at a high concentration enhanced the steady level of proline accumulation in cells. This mechanism was studied in detail and we concluded that zinc ions inhibited completely the exchange-exit reaction for proline. Effects of zinc ions on the active transport reaction for leucine were rather simple when compared with these for proline. Zinc ions inhibited strongly the initial rates of leucine uptakes which were driven by endogenous and exogenous energy sources. The ions also inhibited the exchange-exit reaction.
从U24菌株中分离出一株大肠杆菌突变体（S - 1），该突变体缺乏琥珀酸脱氢酶[EC 1.3.99.1]，但具有正常的琥珀酸转运系统以及除琥珀酸外的各种氧化酶活性。利用这些菌株研究了锌离子对琥珀酸、脯氨酸和亮氨酸主动运输反应的影响。锌离子抑制完整细胞的琥珀酸转运反应和琥珀酸氧化。完整细胞中由内源性能量源支持的脯氨酸主动运输反应受到锌离子的轻微抑制。这种抑制作用不会因大量过量的镁离子而逆转。脯氨酸的主动摄取初始速率因琥珀酸和甘油等外源性能量源而增加，而锌离子则极大地抑制了这些作用。然而，锌离子的存在略微增强了依赖D - 乳酸的脯氨酸摄取。发现高浓度的锌离子提高了细胞中脯氨酸积累的稳定水平。对这一机制进行了详细研究，我们得出结论，锌离子完全抑制了脯氨酸的交换 - 排出反应。与脯氨酸相比，锌离子对亮氨酸主动运输反应的影响较为简单。锌离子强烈抑制由内源性和外源性能量源驱动的亮氨酸摄取初始速率。这些离子还抑制了交换 - 排出反应。
