Chatterjee A, Bhattacharya A K
Radiat Res. 1986 Nov;108(2):189-95.
Gamma irradiation of Escherichia coli B/r caused a dose-dependent inhibition of the capacity of the cells to synthesize L-arabinose isomerase in response to the inducer. At higher doses (18 krad and above), postirradiation incubation led to further inhibition of the capacity to synthesize L-arabinose isomerase, whereas cells receiving lower doses recovered from the damage to the enzyme synthesizing system following incubation. Cyclic AMP partially reversed the inhibitory effect on L-arabinose isomerase induction produced immediately after irradiation by all gamma-ray doses (up to 30 krad), but the enhanced inhibitory effect caused by induction in cells irradiated at higher doses could not be reversed by the nucleotide. It is suggested that although catabolite repression is partly responsible for causing the inhibition of the enzyme synthesizing capacity of the cells observed immediately after gamma irradiation, the enhanced inhibition caused by incubating cells irradiated at higher doses is not due to interference with the control mechanism regulated by catabolite repression.
用伽马射线照射大肠杆菌B/r，会导致细胞响应诱导剂合成L-阿拉伯糖异构酶的能力受到剂量依赖性抑制。在较高剂量（18千拉德及以上）下，辐照后孵育会导致合成L-阿拉伯糖异构酶的能力进一步受到抑制，而接受较低剂量辐照的细胞在孵育后从酶合成系统的损伤中恢复。环磷酸腺苷（cAMP）部分逆转了所有伽马射线剂量（高达30千拉德）辐照后立即产生的对L-阿拉伯糖异构酶诱导的抑制作用，但较高剂量辐照的细胞中诱导产生的增强抑制作用不能被该核苷酸逆转。有人提出，虽然分解代谢物阻遏在一定程度上导致了伽马辐照后立即观察到的细胞酶合成能力的抑制，但较高剂量辐照的细胞孵育导致的增强抑制并非由于干扰了由分解代谢物阻遏调节的控制机制。
