Koplove H M, Cooney C L
J Bacteriol. 1978 Jun;134(3):992-1001. doi: 10.1128/jb.134.3.992-1001.1978.
The synthesis of acetate kinase by Escherichia coli ATCC 9637 was studied during growth in anaerobic continuous cultures under steady-state and transient conditions. During growth in anaerobic, glucose-limited chemostats, acetate kinase synthesis was linearly associated with growth. Two types of non-steady-state transients were studied: the perturbation in one was the addition of glucose alone, and, in the second, glucose plus Casamino Acids. During the nutritional shift-up in the second case, but not in the first, the instantaneous specific acetate kinase activities and specific synthesis rates exceeded pre- and postshift values. Trajectory curves demonstrated that the increase in specific activity remained within the bounds of values obtainable under steady-state conditions with minimal and Casamino Acids media. Specific synthesis rates, however, greatly exceeded steady-state values. Enzyme yield values on glucose after the transient nutritional shift-up increased up to fivefold. Active protein synthesis is shown to be necessary to achieve the enhanced specific synthesis rates and enzyme yields. The results from these transient responses are discussed in terms of a conceptful model for metabolic regulation.
对大肠杆菌ATCC 9637在稳态和瞬态条件下厌氧连续培养生长过程中乙酸激酶的合成进行了研究。在厌氧、葡萄糖限制的恒化器中生长时，乙酸激酶的合成与生长呈线性相关。研究了两种非稳态瞬态：一种扰动是单独添加葡萄糖，另一种是葡萄糖加酪蛋白氨基酸。在第二种情况下的营养上调过程中，而不是在第一种情况下，瞬时比乙酸激酶活性和比合成速率超过了上调前和上调后的数值。轨迹曲线表明，比活性的增加仍在使用最低限度培养基和酪蛋白氨基酸培养基在稳态条件下可获得的数值范围内。然而，比合成速率大大超过了稳态值。瞬态营养上调后基于葡萄糖的酶产量值增加了高达五倍。结果表明，活跃的蛋白质合成对于实现提高的比合成速率和酶产量是必要的。根据代谢调节的概念模型讨论了这些瞬态反应的结果。
