Tomilin N V, Barenfel'd L S
Biokhimiia. 1977 Jul;42(7):1173-83.
Endonucleases from Micrococcus luteus that induce single-strand breaks in gamma-irradiated DNA have been separated chromatographycally into two groups. The first group involves two different enzymes: AP-endonuclease II (mol. weight 30 000) and AP, UV-endonuclease I (mol. weight 15 000) that recognize alkali-labile lesions in gamma-irradiated DNA and apurinic sites in DNA heated at 70 degrees C, pH 6.08 AP-endonuclease II in cooperation with DNA polymerase from M. luteus and T4 phage-induced polynucleotide ligase is capable of carrying out in vitro complete excision repair of alkali-labile lesins in gamma-irradiated DNA. The second group involves gamma-endonucleases X and Y that act on alkalistable gamma-ray lesions. gamma-endonucleases X and Y can be separated by chromatography on DEAE-cellulose but possess similar properties. Activity of gamma-endonucleases toward gamma-irradiated DNA is inhibited by only heavily UV-irradiated DNA (15 000 ergs/mm2). The data are consistent with the hypothesis that gamma-endonucleases are specific for thymine glycols (t' and tUV) in UV- and gamma-irradiated DNA.
从藤黄微球菌中分离出的能在γ射线照射的DNA中诱导单链断裂的核酸内切酶，已通过色谱法分为两组。第一组包括两种不同的酶：AP核酸内切酶II（分子量30000）和AP、UV核酸内切酶I（分子量15000），它们识别γ射线照射的DNA中的碱不稳定损伤以及在70℃、pH 6.0加热的DNA中的脱嘌呤位点。AP核酸内切酶II与藤黄微球菌的DNA聚合酶和T4噬菌体诱导的多核苷酸连接酶协同作用，能够在体外对γ射线照射的DNA中的碱不稳定损伤进行完全切除修复。第二组包括作用于碱稳定的γ射线损伤的γ核酸内切酶X和Y。γ核酸内切酶X和Y可以通过在DEAE - 纤维素上的色谱法分离，但具有相似的性质。γ核酸内切酶对γ射线照射的DNA的活性仅被重度紫外线照射的DNA（15000尔格/平方毫米）抑制。这些数据与γ核酸内切酶对紫外线和γ射线照射的DNA中的胸腺嘧啶二醇（t'和tUV）具有特异性的假设一致。
