Nakamura H, Morita T, Yoshida S
Int J Radiat Biol Relat Stud Phys Chem Med. 1980 Oct;38(4):449-58. doi: 10.1080/09553008014551811.
Using mammalian DNA polymerases alpha, beta and terminal deoxynucleotidyl transferase, we have examined the inhibitory action of X-irradiated DNA on in vitro DNA synthetic activities of these enzymes. It was found that DNA polymerase beta was highly sensitive inhibition by the irradiated DNA as well as DNA polymerases I of E. coli, while DNA polymerase alpha was at least two hundred times more resistant to inhibition than DNA ploymerase beta. Terminal deoxynucleotidyl transferase was inhibited moderately by the single-stranded form of the irradiated DNA. Since the inhibition was competitive with respect to a template-initiator for all DNA polymerases or an initiator for terminal deoxynucleotidyl transferase, the differences in sensitivities to the inhibition may be due to the different affinities of the enzymes to the X-ray-induced inhibitory sites on the DNA strand.
利用哺乳动物的DNA聚合酶α、β和末端脱氧核苷酸转移酶，我们研究了X射线照射过的DNA对这些酶体外DNA合成活性的抑制作用。结果发现，DNA聚合酶β对照射过的DNA的抑制高度敏感，对大肠杆菌的DNA聚合酶I也是如此，而DNA聚合酶α对抑制的抗性至少是DNA聚合酶β的200倍。末端脱氧核苷酸转移酶受到照射过的DNA单链形式的中度抑制。由于对所有DNA聚合酶而言，这种抑制作用与模板引发剂竞争，对末端脱氧核苷酸转移酶而言与引发剂竞争，因此对抑制敏感性的差异可能是由于这些酶对DNA链上X射线诱导的抑制位点的亲和力不同。
